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Sample records for junction solar cell

  1. Dot junction solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Crotty, G. T.

    1986-01-01

    A design of solar cells with reduced junction area on the cell surface is investigated for reduction of saturation current and increase in open-circuit voltage. Equidiameter dot junctions distributed across the surface of the cell offer an efficient alternative, with variations in dot diameter and in the spacing between dots giving the required variations in the ratio of junction area to total surface area. A simplified analysis for short-circuit current and other cell parameters, which enables cell design optimization, is presented. Experimental solar-cell performance results, as functions of different area ratios, are presented and compared with the model. It is shown that saturation current reduction is possible for achieving efficiencies as high as 18 percent in flat-plate terrestrial applications.

  2. Quantum junction solar cells.

    PubMed

    Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics.

  3. Multi-junction solar cell device

    DOEpatents

    Friedman, Daniel J.; Geisz, John F.

    2007-12-18

    A multi-junction solar cell device (10) is provided. The multi-junction solar cell device (10) comprises either two or three active solar cells connected in series in a monolithic structure. The multi-junction device (10) comprises a bottom active cell (20) having a single-crystal silicon substrate base and an emitter layer (23). The multi-junction device (10) further comprises one or two subsequent active cells each having a base layer (32) and an emitter layer (23) with interconnecting tunnel junctions between each active cell. At least one layer that forms each of the top and middle active cells is composed of a single-crystal III-V semiconductor alloy that is substantially lattice-matched to the silicon substrate (22). The polarity of the active p-n junction cells is either p-on-n or n-on-p. The present invention further includes a method for substantially lattice matching single-crystal III-V semiconductor layers with the silicon substrate (22) by including boron and/or nitrogen in the chemical structure of these layers.

  4. Plasmon Enhanced Hetero-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Long, Gen; Ching, Levine; Sadoqi, Mostafa; Xu, Huizhong

    2015-03-01

    Here we report a systematic study of plasmon-enhanced hetero-junction solar cells made of colloidal quantum dots (PbS) and nanowires (ZnO), with/without metal nanoparticles (Au). The structure of solar cell devices was characterized by AFM, SEM and profilometer, etc. The power conversion efficiencies of solar cell devices were characterized by solar simulator (OAI TriSOL, AM1.5G Class AAA). The enhancement in the photocurrent due to introduction of metal nanoparticles was obvious. We believe this is due to the plasmonic effect from the metal nanoparticles. The correlation between surface roughness, film uniformity and device performance was also studied.

  5. Studies of silicon PN junction solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.

    1975-01-01

    Silicon pn junction solar cells made with low-resistivity substrates show poorer performance than traditional theory predicts. The purpose of this research was to identify and characterize the physical mechanisms responsible for the discrepancy. Attention was concentrated on the open circuit voltage in shallow junction cells of 0.1 ohm-cm substrate resistivity. A number of possible mechanisms that can occur in silicon devices were considered. Two mechanisms which are likely to be of main importance in explaining the observed low values of open-circuit voltage were found: (1) recombination losses associated with defects introduced during junction formation, and (2) inhomogeneity of defects and impurities across the area of the cell. To explore these theoretical anticipations, various diode test structures were designed and fabricated and measurement configurations for characterizing the defect properties and the areal inhomogeneity were constructed.

  6. Studies of silicon pn junction solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.

    1977-01-01

    Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

  7. Excess junction current of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Wang, E. Y.; Legge, R. N.; Christidis, N.

    1973-01-01

    The current-voltage characteristics of n(plus)-p silicon solar cells with 0.1, 1.0, 2.0, and 10 ohm-cm p-type base materials have been examined in detail. In addition to the usual I-V measurements, we have studied the temperature dependence of the slope of the I-V curve at the origin by the lock-in technique. The excess junction current coefficient (Iq) deduced from the slope at the origin depends on the square root of the intrinsic carrier concentration. The Iq obtained from the I-V curve fitting over the entire forward bias region at various temperatures shows the same temperature dependence. This result, in addition to the presence of an aging effect, suggest that the surface channel effect is the dominant cause of the excess junction current.

  8. Studies of silicon p-n junction solar cells

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Lindholm, F. A.

    1979-01-01

    To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

  9. Elongated nanostructures for radial junction solar cells

    NASA Astrophysics Data System (ADS)

    Kuang, Yinghuan; Di Vece, Marcel; Rath, Jatindra K.; van Dijk, Lourens; Schropp, Ruud E. I.

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  10. Elongated nanostructures for radial junction solar cells.

    PubMed

    Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  11. Improved High/Low Junction Silicon Solar Cell

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Pao, S. C.; Lindholm, F. A.; Fossum, J. G.

    1986-01-01

    Method developed to raise value of open-circuit voltage in silicon solar cells by incorporating high/low junction in cell emitter. Power-conversion efficiency of low-resistivity silicon solar cell considerably less than maximum theoretical value mainly because open-circuit voltage is smaller than simple p/n junction theory predicts. With this method, air-mass-zero opencircuit voltage increased from 600 mV level to approximately 650 mV.

  12. Fabrication and analysis of dot junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Crotty, G. T.; Daud, T.

    1985-01-01

    A design of solar cells with reduced junction area on the cell surface is investigated for reduction of saturation current and increase in open-circuit voltage. Equidiameter dot junctions distributed across the surface of the cell offer an efficient alternative, with variations in dot diameter and in the spacing between dots giving the required variations in the ratio of junctions area to total surface area. A simplified analysis for short-circuit current and other cell parameters, which enables cell design optimization, is presented. Efficiencies beyond 18 percent are obtainable in flat-plate terrestrial applications. Experimental solar-cell performance results, as functions of different area ratios, and bulk doping are presented. It is shown that saturation current reduction and open-circuit voltage increase is obtained by reduced junction area.

  13. Non PN junction solar cells using carrier selective contacts

    NASA Astrophysics Data System (ADS)

    Bowden, Stuart; Ghosh, Kunal; Honsberg, Christiana

    2013-03-01

    A novel device concept utilizing the approach of selectively extracting carriers at the respective contacts is outlined in the work. The dominant silicon solar cell technology is based on a diffused, top-contacted p-n junction on a relatively thick silicon wafer for both commercial and laboratory solar cells. The VOC and hence the efficiency of a diffused p-n junction solar cell is limited by the emitter recombination current and a value of 720 mV is considered to be the upper limit. The value is more than 100 mV smaller than the thermodynamic limit of VOC as applicable for silicon based solar cells. Also, in diffused junction the use of thin wafers (< 50 um) are problematic because of the requirement of high temperature processing steps. But a number of roadmaps have identified solar cells manufactured on thinner silicon wafers to achieve lower cost and higher efficiency. The carrier selective contact device provides a novel alternative to diffused p-n junction solar cells by eliminating the need for complementary doping to form the emitter and hence it allows the solar cells to achieve a VOC of greater than 720 mV. Also, the complete device structure can be fabricated with low temperature thin film deposition or organic coating on silicon substrates and thus epitaxially grown silicon or kerfless silicon, in addition to standard silicon wafers can be utilized.

  14. Development and fabrication of a solar cell junction processing system

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A processing system capable of producing solar cell junctions by ion implantation followed by pulsed electron beam annealing was developed and constructed. The machine was to be capable of processing 4-inch diameter single-crystal wafers at a rate of 10(7) wafers per year. A microcomputer-controlled pulsed electron beam annealer with a vacuum interlocked wafer transport system was designed, built and demonstrated to produce solar cell junctions on 4-inch wafers with an AMI efficiency of 12%. Experiments showed that a non-mass-analyzed (NMA) ion beam could implant 10 keV phosphorous dopant to form solar cell junctions which were equivalent to mass-analyzed implants. A NMA ion implanter, compatible with the pulsed electron beam annealer and wafer transport system was designed in detail but was not built because of program termination.

  15. Proton radiation damage in vertical junction solar cells

    NASA Astrophysics Data System (ADS)

    Walker, D. H.; Statler, R. L.

    A comparative experimental study of proton radiation damage in silicon vertical junction (VJ) and silicon planar solar cells was performed at three energies, 1-MeV, 2-MeV, and 3.5-MeV, for a normal incidence monoenergetic proton beam. Proton fluence levels up to 3 x 10 to the 12th protons/sq cm were achieved, with solar cell I-V characterization measurements performed at incremental fluences, using a recently calibrated Spectrolab X-25L Solar Simulator. The VJ cells were made from 0.4 ohm-cm silicon, while the planar cells were made from 10 ohm-cm silicon and had a back surface reflector. The VJ cells proved to be more radiation resistant than the baseline planar cells, and the damage data from various proton energies indicate that the vertical junction concept does work effectively for maintaining high collection efficiency despite heavy radiation exposure.

  16. Tunnel junctions for InP-on-Si solar cells

    NASA Technical Reports Server (NTRS)

    Keavney, C.; Vernon, S.; Haven, V.

    1991-01-01

    Growing, by metalorganic chemical vapor deposition, a tunnel junction is described, which makes possible and ohmic back contact in an n-on-p InP solar cell on a silicon substrate. The junction between heavily doped layers of p-type InGaAs and n-type InP shows resistance low enough not to affect the performance of these cells. InP solar cells made on n-type Si substrates with this structure were measured with an efficiency of 9.9 percent. Controls using p-type GaAs substrates showed no significant difference in cell performance, indicating that the resistance associated with the tunnel junction is less than about 0.1 ohm/sq cm.

  17. Development and fabrication of a solar cell junction processing system

    NASA Technical Reports Server (NTRS)

    Bunker, S.

    1981-01-01

    A solar cell junction processing system was developed and fabricated. A pulsed electron beam for the four inch wafers is being assembled and tested, wafers were successfully pulsed, and solar cells fabricated. Assembly of the transport locks is completed. The transport was operated successfully but not with sufficient reproducibility. An experiment test facility to examine potential scaleup problems associated with the proposed ion implanter design was constructed and operated. Cells were implanted and found to have efficiency identical to the normal Spire implant process.

  18. Research on gallium arsenide diffused junction solar cells

    NASA Technical Reports Server (NTRS)

    Borrego, J. M.; Ghandi, S. K.

    1984-01-01

    The feasibility of using bulk GaAs for the fabrication of diffused junction solar cells was determined. The effects of thermal processing of GaAs was studied, and the quality of starting bulk GaAs for this purpose was assessed. These cells are to be made by open tube diffusion techniques, and are to be tested for photovoltaic response under AMO conditions.

  19. Ion implantation of solar cell junctions without mass analysis

    NASA Technical Reports Server (NTRS)

    Fitzgerald, D.; Tonn, D. G.

    1981-01-01

    This paper is a summary of an investigation to determine the feasibility of producing solar cells by means of ion implantation without the use of mass analysis. Ion implants were performed using molecular and atomic phosphorus produced by the vaporization of solid red phosphorus and ionized in an electron bombardment source. Solar cell junctions were ion implanted by mass analysis of individual molecular species and by direct unanalyzed implants from the ion source. The implant dose ranged from 10 to the 14th to 10 to the 16th atoms/sq cm and the energy per implanted atom ranged from 5 KeV to 40 KeV in this study.

  20. Low-high junction theory applied to solar cells

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

    1973-01-01

    Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open circuit voltage and improved radiation resistance. Several analytical models for open circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero SRV case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells. Detailed descriptions and derivations for the models are included. The correspondences between them are discussed. This modeling suggests that the meaning of minority carrier diffusion length measured in BSF cells be reexamined.

  1. Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint

    SciTech Connect

    Young, D. L.; Li, J. V.; Teplin, C. W.; Stradins, P.; Branz, H. M.

    2011-07-01

    We report our progress toward low-temperature HWCVD epitaxial film silicon solar cells on inexpensive seed layers, with a focus on the junction transport physics exhibited by our devices. Heterojunctions of i/p hydrogenated amorphous Si (a-Si) on our n-type epitaxial crystal Si on n++ Si wafers show space-charge-region recombination, tunneling or diffusive transport depending on both epitaxial Si quality and the applied forward voltage.

  2. Low-high junction theory applied to solar cells

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

    1974-01-01

    Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open-circuit voltage and improved radiation resistance. Several analytical models for open-circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero surface recombination velocity (SRV) case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells.

  3. Molecular beam epitaxy growth of germanium junctions for multi-junction solar cell applications

    NASA Astrophysics Data System (ADS)

    Masuda, T.; Faucher, J.; Lee, M. L.

    2016-11-01

    We report on the molecular beam epitaxy (MBE) growth and device characteristics of Ge solar cells. Integrating a Ge bottom cell beneath a lattice-matched triple junction stack grown by MBE could enable ultra-high efficiencies without metamorphic growth or wafer bonding. However, a diffused junction cannot be readily formed in Ge by MBE due to the low sticking coefficient of group-V molecules on Ge surfaces. We therefore realized Ge junctions by growth of homo-epitaxial n-Ge on p-Ge wafers within a standard III-V MBE system. We then fabricated Ge solar cells, finding growth temperature and post-growth annealing to be key factors for achieving high efficiency. Open-circuit voltage and fill factor values of ~0.175 V and ~0.59 without a window layer were obtained, both of which are comparable to diffused Ge junctions formed by metal-organic vapor phase epitaxy. We also demonstrate growth of high-quality, single-domain GaAs on the Ge junction, as needed for subsequent growth of III-V subcells, and that the surface passivation afforded by the GaAs layer slightly improves the Ge cell performance.

  4. Transport Imaging of Multi-Junction and CIGS Solar Cell Materials

    DTIC Science & Technology

    2011-12-01

    solar energy. Indium Gallium Phosphide (InGaP) is commonly used as the top cell in multi-junction cells grown on... solar energy. Indium Gallium Phosphide (InGaP) is commonly used as the top cell in multi-junction cells grown on Germanium (Ge) or Gallium Arsenide...mobility of several Indium Gallium Phosphide (InGaP) materials for use in multi-junction solar cells . This will be done through transport imaging,

  5. Crystalline Silicon/Graphene Oxide Hybrid Junction Solar Cells

    NASA Astrophysics Data System (ADS)

    Liu, Qiming; Wanatabe, Fumiya; Hoshino, Aya; Ishikawa, Ryo; Gotou, Takuya; Ueno, Keiji; Shirai, Hajime

    2012-10-01

    Soluble graphene oxide (GO) and plasma-reduced (pr-) GO were investigated using crystalline silicon (c-Si) (100)/GO/pr-GO hybrid junction solar cells. Their photovoltaic performances were compared with those of c-Si/GO/pristine conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) heterojunction and c-Si/PEDOT:PSS:GO composite devices. The c-Si/GO/pr-GO and conductive PEDOT:PSS/Al heterojunction solar cells showed power conversion efficiencies of 6.5 and 8.2%, respectively, under illumination with AM 1.5 G 100 mW/cm2 simulated solar light. A higher performance of 10.7% was achieved using the PEDOT:PSS:GO (12.5 wt %) composite device. These findings imply that soluble GO, pr-GO, and the PEDOT:PSS:GO composite are promising materials as hole transport and transparent conductive layers for c-Si/organic hybrid junction solar cells.

  6. Full potential of radial junction Si thin film solar cells with advanced junction materials and design

    NASA Astrophysics Data System (ADS)

    Qian, Shengyi; Misra, Soumyadeep; Lu, Jiawen; Yu, Zhongwei; Yu, Linwei; Xu, Jun; Wang, Junzhuan; Xu, Ling; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-07-01

    Combining advanced materials and junction design in nanowire-based thin film solar cells requires a different thinking of the optimization strategy, which is critical to fulfill the potential of nano-structured photovoltaics. Based on a comprehensive knowledge of the junction materials involved in the multilayer stack, we demonstrate here, in both experimental and theoretical manners, the potential of hydrogenated amorphous Si (a-Si:H) thin film solar cells in a radial junction (RJ) configuration. Resting upon a solid experimental basis, we also assess a more advanced tandem RJ structure with radially stacking a-Si:H/nanocrystalline Si (nc-Si:H) PIN junctions, and show that a balanced photo-current generation with a short circuit current density of Jsc = 14.2 mA/cm2 can be achieved in a tandem RJ cell, while reducing the expensive nc-Si:H absorber thickness from 1-3 μ m (in planar tandem cells) to only 120 nm. These results provide a clearly charted route towards a high performance Si thin film photovoltaics.

  7. Development of thin wraparound junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Ho, F.; Iles, P. A.

    1981-01-01

    The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

  8. Development of a Novel Hybrid Multi-Junction Architecture for Silicon Solar Cells

    DTIC Science & Technology

    2015-03-26

    DEVELOPMENT OF A NOVEL HYBRID MULTI-JUNCTION ARCHITECTURE FOR SILICON SOLAR CELLS THESIS...the United States. AFIT-ENG-MS-15-M-026 DEVELOPMENT OF A NOVEL HYBRID MULTI-JUNCTION ARCHITECTURE FOR SILICON SOLAR CELLS THESIS...AFIT-ENG-MS-15-M-026 DEVELOPMENT OF A NOVEL HYBRID MULTI-JUNCTION ARCHITECTURE FOR SILICON SOLAR CELLS Robert S. LaFleur 1st

  9. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  10. Simulation of the Mars Surface Solar Spectra for Optimized Performance of Triple-Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Edmondson, Kenneth M.; Joslin, David E.; Fetzer, Chris M.; King, RIchard R.; Karam, Nasser H.; Mardesich, Nick; Stella, Paul M.; Rapp, Donald; Mueller, Robert

    2007-01-01

    The unparalleled success of the Mars Exploration Rovers (MER) powered by GaInP/GaAs/Ge triple-junction solar cells has demonstrated a lifetime for the rovers that exceeded the baseline mission duration by more than a factor of five. This provides confidence in future longer-term solar powered missions on the surface of Mars. However, the solar cells used on the rovers are not optimized for the Mars surface solar spectrum, which is attenuated at shorter wavelengths due to scattering by the dusty atmosphere. The difference between the Mars surface spectrum and the AM0 spectrum increases with solar zenith angle and optical depth. The recent results of a program between JPL and Spectrolab to optimize GaInP/GaAs/Ge solar cells for Mars are presented. Initial characterization focuses on the solar spectrum at 60-degrees zenith angle at an optical depth of 0.5. The 60-degree spectrum is reduced to 1/6 of the AM0 intensity and is further reduced in the blue portion of the spectrum. JPL has modeled the Mars surface solar spectra, modified an X-25 solar simulator, and completed testing of Mars-optimized solar cells previously developed by Spectrolab with the modified X-25 solar simulator. Spectrolab has focused on the optimization of the higher efficiency Ultra Triple-Junction (UTJ) solar cell for Mars. The attenuated blue portion of the spectrum requires the modification of the top sub-cell in the GaInP/GaAs/Ge solar cell for improved current balancing in the triple-junction cell. Initial characterization confirms the predicted increase in power and current matched operation for the Mars surface 60-degree zenith angle solar spectrum.

  11. Thermodynamic limit of bifacial double-junction tandem solar cells

    NASA Astrophysics Data System (ADS)

    Ryyan Khan, M.; Alam, Muhammad A.

    2015-11-01

    A traditional single-junction solar panel cannot harness ground-scattered light (albedo reflectance, RA ), and also suffers from the fundamental sub-band-gap and the thermalization losses. In this paper, we explain how a "bifacial tandem" panel would dramatically reduce these losses, with corresponding improvement in thermodynamic performance. Our study predicts (i) the optimum combination of the band-gaps, empirically given by Eg(t ) o p t≈Eg(b ) o p t(2 +RA)/3 +(1 -RA) and the (ii) corresponding optimum normalized output power given by ηT(op t ) *≈RA (2 ηSJ (o p t ) ) +(1 -RA ) ηDJ (o p t ) . Empirically, ηT(op t ) * interpolates between the thermodynamic efficiency limit of classical double-junction tandem cell ( ηDJ ) and twice that of a single-junction cell ( ηSJ ). We conclude by explaining how the fundamental loss mechanisms evolve with RA in a bifacial tandem cell.

  12. Mechanically Stacked Four-Junction Concentrator Solar Cells

    SciTech Connect

    Steiner, Myles A.; Geisz, John F.; Ward, J. Scott; Garcia, Ivan; Friedman, Daniel J.; King, Richard R.; Chiu, Philip T.; France, Ryan M.; Duda, Anna; Olavarria, Waldo J.; Young, Michelle; Kurtz, Sarah R.

    2015-06-14

    Multijunction solar cells can be fabricated by bonding together component cells that are grown separately. Because the component cells are each grown lattice-matched to suitable substrates, this technique allows alloys of different lattice constants to be combined without the structural defects introduced when using metamorphic buffers. Here we present results on the fabrication and performance of four-junction mechanical stacks composed of GaInP/GaAs and GaInAsP/GaInAs tandems, grown on GaAs and InP substrates, respectively. The two tandems were bonded together with a low-index, transparent epoxy that acts as an omni-directional reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the sub-bandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and thus higher subcell voltage, compared with GaAs subcells without enhanced internal optics; all four subcells exhibit excellent material quality. The device was fabricated with four contact terminals so that each tandem can be operated at its maximum power point, which raises the cumulative efficiency and decreases spectral sensitivity. Efficiencies exceeding 38% at one-sun have been demonstrated. Eliminating the series resistance is the key challenge for the concentrator cells. We will discuss the performance of one-sun and concentrator versions of the device, and compare the results to recently fabricated monolithic four-junction cells.

  13. Application of laser annealing to solar cell junction formation

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.; Lopez, M.; Josephs, R. H.

    1981-01-01

    The possibility of using high-energy Q-switched Nd:glass lasers to form pn junctions in solar cells by annealing ion-implanted substrates is investigated. The properties of laser annealed cells are analyzed by electrical, transmission electron microscopy, Rutherford backscattering and secondary ion mass spectrometry techniques. Tests indicate the laser annealed substrates to be damage-free and electrically active. Similar reference analysis of ion-implanted furnace-annealed substrates reveals the presence of residual defects in the form of dislocation lines and loops with substantial impurity redistribution evident for some anneal temperature/time regimes. Fabricated laser annealed cells exhibit excellent conversion efficiency. It is noted that additional improvements are anticipated once the anneal parameters for a back surface field are optimized.

  14. Studies of silicon p-n junction solar cells. [open circuit photovoltage

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.

    1976-01-01

    Single crystal silicon p-n junction solar cells made with low resistivity substrates show poorer solar energy conversion efficiency than traditional theory predicts. The physical mechanisms responsible for this discrepancy are identified and characterized. The open circuit voltage in shallow junction cells of about 0.1 ohm/cm substrate resistivity is investigated under AMO (one sun) conditions.

  15. Modeling Radiation Effects on a Triple Junction Solar Cell using Silvaco ATLAS

    DTIC Science & Technology

    2012-06-01

    Indium - Gallium -Phosphide and Germanium solar cells . The effects of...32. 37 Figure 32. InGaP/GaAs/Ge Solar Cell . From [37]. The indium gallium phosphide (InGaP) material creates the least current but the highest...Phosphide, and Gallium Arsenide solar cells individually and together in a triple junction cell is presented in this thesis. A discussion on

  16. Simulation of the Mars surface solar spectra for optimized performance of triple junction solar cells

    NASA Technical Reports Server (NTRS)

    Edmondson, Kenneth M.; Joslin, David E.; Fetzer, Chris M.; King, Richard R.; Karam, Nasser H.; Mardesich, Nick; Stella, Paul M.; Rapp, Donald; Mueller, Robert

    2005-01-01

    The unparalleled success of the Mars Exploration Rovers (MER) powered by GaInP/GaAs/Ge triple-junction solar cells has demonstrated a lifetime for the rovers that exceeded the baseline mission duration by more than a factor of five.

  17. Theoretical performance of multi-junction solar cells combining III-V and Si materials.

    PubMed

    Mathews, Ian; O'Mahony, Donagh; Corbett, Brian; Morrison, Alan P

    2012-09-10

    A route to improving the overall efficiency of multi-junction solar cells employing conventional III-V and Si photovoltaic junctions is presented here. A simulation model was developed to consider the performance of several multi-junction solar cell structures in various multi-terminal configurations. For series connected, 2-terminal triple-junction solar cells, incorporating an AlGaAs top junction, a GaAs middle junction and either a Si or InGaAs bottom junction, it was found that the configuration with a Si bottom junction yielded a marginally higher one sun efficiency of 41.5% versus 41.3% for an InGaAs bottom junction. A significant efficiency gain of 1.8% over the two-terminal device can be achieved by providing an additional terminal to the Si bottom junction in a 3-junction mechanically stacked configuration. It is shown that the optimum performance can be achieved by employing a four-junction series-connected mechanically stacked device incorporating a Si subcell between top AlGaAs/GaAs and bottom In0.53Ga0.47As cells.

  18. Comparative performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.; Parat, K. K.

    1987-01-01

    A comparison is made between indium phosphide solar cells whose p-n junctions were processed by open tube capped diffusion, and closed tube uncapped diffusion, of sulfur into Czochralski grown p-type substrates. Air mass zero, total area, efficiencies ranged from 10 to 14.2 percent, the latter value attributed to cells processed by capped diffusion. The radiation resistance of these latter cells was slightly better, under 1 MeV electron irradiation. However, rather than being process dependent, the difference in radiation resistance could be attributed to the effects of increased base dopant concentration. In agreement with previous results, both cells exhibited radiation resistance superior to that of gallium arsenide. The lowest temperature dependency of maximum power was exhibited by the cells prepared by open tube capped diffusion. Contrary to previous results, no correlation was found between open circuit voltage and the temperature dependency of Pmax. It was concluded that additional process optimization was necessary before concluding that one process was better than another.

  19. Performance Analysis of Ultra-Thin Silicon Based Tunnel Junctions for Tandem Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, H.; Rostami, A.; Dolatyari, M.; Rostami, G.

    Nowadays silicon solar cells have an efficiency of up to 20 % and in order to increase the efficiency of them, fabrication of multi-junction thin film solar cells with different band gaps is one of the most promising approaches. The silicon based tandem solar cells are third generation new style solar cells with ultra-high efficiency. The sub-cells in a tandem solar cell have different energy band gaps. In order to match the currents between sub-cells, tunnel junctions are used to connect the sub-cells. This work will concentrate on simulating the tunnel junction for application as part of multi-junction solar cell. In this way dopant concentration is changed and the tunnel junction current-voltage characteristics and their Energy band diagram in different dopant levels under equilibrium condition for moderate and usual doping have been calculated. An n++-Si/p++-Si tunnel junction is selected to simulate the overall characteristics of cell by numerical finite element method. We have simulated a symmetric silicon tunnel junction with thickness of 25 nm for n-type and 25 nm for p-type silicon by changing doping value from 1 × 10e20 cm-3 to 2 × 10e20 cm-3. The simulation results show that the doping concentration of 2 × 10e20 cm-3 is suitable for both sides.

  20. Investigation of multi-junction solar cells using electrostatic force microscopy methods.

    PubMed

    Moczała, M; Sosa, N; Topol, A; Gotszalk, T

    2014-06-01

    Multi-junction III-V solar cells are designed to have a much broader absorption of the solar spectrum than Si-based or single junctions, thus yield the highest conversion. The conversion efficiency can be further scaled with sun concentration. The ability of high conversion efficiencies makes multi-junction prime candidates for fine-tuning explorations aimed at getting closer to the theoretical efficiencies. In this paper, we report on electrostatic force microscopy (EFM) measurements of the built-in potential of multi-junction III-V semiconductor-based solar cells. Kelvin probe force microscopy (KPFM) was employed to qualitatively study the width and electrical properties of individual junctions, i.e., built-in potential, activity, and thickness of the p-n junctions. In addition, the voltage drops across individual solar cell p-n junctions were measured using Kelvin probe microscopy under various operation conditions: dark; illuminated; short-circuit; and biased. We present a method which enables the measurement of a working structure, while focusing on the electrical characteristics of an individual junction by virtue of selecting the spectral range of the illumination used. We show that these pragmatic studies can provide a feedback to improve photovoltaic device design, particularly of operation under a current mismatched situation. This new analysis technique offers additional insights into behavior of the multi-junction solar cell and shows promise for further progress in this field.

  1. Analysis of a four lamp flash system for calibrating multi-junction solar cells under concentrated light

    SciTech Connect

    Schachtner, Michael Prado, Marcelo Loyo; Reichmuth, S. Kasimir; Siefer, Gerald; Bett, Andreas W.

    2015-09-28

    It has been known for a long time that the precise characterization of multi-junction solar cells demands spectrally tunable solar simulators. The calibration of innovative multi-junction solar cells for CPV applications now requires tunable solar simulators which provide high irradiation levels. This paper describes the commissioning and calibration of a flash-based four-lamp simulator to be used for the measurement of multi-junction solar cells with up to four subcells under concentrated light.

  2. Improved GaAs solar cells with very thin junctions

    NASA Technical Reports Server (NTRS)

    Hovel, H. J.; Woodall, J. M.

    1976-01-01

    Violet cells with 500-1000 A junction depths have been made in GaAs by narrow junction diffusion followed by anodization. The best AM0 efficiencies obtained by this technique have been 10.5% (14% at AM1). GaAlAs-GaAs structures with very thin GaAlAs layers are much more promising, and efficiencies of over 18% at AM0 have been measured (21.9% at AM1).

  3. Modeling and Simulation of a Dual-Junction CIGS Solar Cell Using Silvaco ATLAS

    DTIC Science & Technology

    2012-12-01

    Indium Gallium Selenide (CIGS) photovoltaic cell is investigated in this thesis. Research into implementing a dual-junction solar cell ...is the use of thin-film solar cells (TFSC) such as the Copper Indium Gallium Selenide, Cu(In,Ga)Se2, (CIGS). Despite their lower cost of production...Silvaco ATLASTM model of a single CIGS cell was created by utilizing actual solar cell parameters (such as layer thicknesses, gallium ratio,

  4. Single-junction solar cells with the optimum band gap for terrestrial concentrator applications

    DOEpatents

    Wanlass, Mark W.

    1994-01-01

    A single-junction solar cell having the ideal band gap for terrestrial concentrator applications. Computer modeling studies of single-junction solar cells have shown that the presence of absorption bands in the direct spectrum has the effect of "pinning" the optimum band gap for a wide range of operating conditions at a value of 1.14.+-.0.02 eV. Efficiencies exceeding 30% may be possible at high concentration ratios for devices with the ideal band gap.

  5. Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements.

    PubMed

    Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Toshimitsu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-16

    World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells.

  6. Design High-Efficiency III-V Nanowire/Si Two-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhang, Y.; Zhang, D.; He, S.; Li, X.

    2015-06-01

    In this paper, we report the electrical simulation results of a proposed GaInP nanowire (NW)/Si two-junction solar cell. The NW physical dimensions are determined for optimized solar energy absorption and current matching between each subcell. Two key factors (minority carrier lifetime, surface recombination velocity) affecting power conversion efficiency (PCE) of the solar cell are highlighted, and a practical guideline to design high-efficiency two-junction solar cell is thus provided. Considering the practical surface and bulk defects in GaInP semiconductor, a promising PCE of 27.5 % can be obtained. The results depict the usefulness of integrating NWs to construct high-efficiency multi-junction III-V solar cells.

  7. Design considerations for the Tandem Junction Solar Cell

    NASA Technical Reports Server (NTRS)

    Matzen, W. T.; Carbajal, B. G.; Hardy, R. W.

    1979-01-01

    Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters.

  8. An efficient triple-junction polymer solar cell having a power conversion efficiency exceeding 11%.

    PubMed

    Chen, Chun-Chao; Chang, Wei-Hsuan; Yoshimura, Ken; Ohya, Kenichiro; You, Jingbi; Gao, Jing; Hong, Zirou; Yang, Yang

    2014-08-27

    Tandem solar cells have the potential to improve photon conversion efficiencies (PCEs) beyond the limits of single-junction devices. In this study, a triple-junction tandem design is demonstrated by employing three distinct organic donor materials having bandgap energies ranging from 1.4 to 1.9 eV. Through optical modeling, balanced photon absorption rates are achieved and, thereby, the photo-currents are matched among the three subcells. Accordingly, an efficient triple-junction tandem organic solar cell can exhibit a record-high PCE of 11.5%.

  9. Performance evaluation of multi-junction solar cells by spatially resolved electroluminescence microscopy.

    PubMed

    Kong, Lijing; Wu, Zhiming; Chen, Shanshan; Cao, Yiyan; Zhang, Yong; Li, Heng; Kang, Junyong

    2015-01-01

    An electroluminescence microscopy combined with a spectroscopy was developed to visually analyze multi-junction solar cells. Triple-junction solar cells with different conversion efficiencies were characterized by using this system. The results showed that the mechanical damages and material defects in solar cells can be clearly distinguished, indicating a high-resolution imaging. The external quantum efficiency (EQE) measurements demonstrated that different types of defects or damages impacted cell performance in various degrees and the electric leakage mostly degraded the EQE. Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC. The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC. This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.

  10. NREL, CSEM Jointly Set New Efficiency Record with Dual-Junction Solar Cell

    SciTech Connect

    2016-01-01

    Scientists set a new world record for converting non-concentrated sunlight into electricity using a dual-junction III-V/Si solar cell. National Renewable Energy Laboratory (NREL) and Swiss Center for Electronics and Microtechnology (CSEM) scientists have collaborated to create a novel tandem solar cell that operates at 29.8% conversion efficiency under non-concentrator (1-sun) conditions. In comparison, the 1-sun efficiency of a silicon (Si) single-junction solar cell is probably still a few years away from converging on its practical limit of about 26%.

  11. Device characterization for design optimization of 4 junction inverted metamorphic concentrator solar cells

    SciTech Connect

    Geisz, John F.; France, Ryan M.; Steiner, Myles A.; Friedman, Daniel J.; García, Iván

    2014-09-26

    Quantitative electroluminescence (EL) and luminescent coupling (LC) analysis, along with more conventional characterization techniques, are combined to completely characterize the subcell JV curves within a fourjunction (4J) inverted metamorphic solar cell (IMM). The 4J performance under arbitrary spectral conditions can be predicted from these subcell JV curves. The internal radiative efficiency (IRE) of each junction has been determined as a function of current density from the external radiative efficiency using optical modeling, but this required the accurate determination of the individual junction current densities during the EL measurement as affected by LC. These measurement and analysis techniques can be applied to any multijunction solar cell. The 4J IMM solar cell used to illustrate these techniques showed excellent junction quality as exhibited by high IRE and a one-sun AM1.5D efficiency of 36.3%. This device operates up to 1000 suns without limitations due to any of the three tunnel junctions.

  12. GaAs nanowire array solar cells with axial p-i-n junctions.

    PubMed

    Yao, Maoqing; Huang, Ningfeng; Cong, Sen; Chi, Chun-Yung; Seyedi, M Ashkan; Lin, Yen-Ting; Cao, Yu; Povinelli, Michelle L; Dapkus, P Daniel; Zhou, Chongwu

    2014-06-11

    Because of unique structural, optical, and electrical properties, solar cells based on semiconductor nanowires are a rapidly evolving scientific enterprise. Various approaches employing III-V nanowires have emerged, among which GaAs, especially, is under intense research and development. Most reported GaAs nanowire solar cells form p-n junctions in the radial direction; however, nanowires using axial junction may enable the attainment of high open circuit voltage (Voc) and integration into multijunction solar cells. Here, we report GaAs nanowire solar cells with axial p-i-n junctions that achieve 7.58% efficiency. Simulations show that axial junctions are more tolerant to doping variation than radial junctions and lead to higher Voc under certain conditions. We further study the effect of wire diameter and junction depth using electrical characterization and cathodoluminescence. The results show that large diameter and shallow junctions are essential for a high extraction efficiency. Our approach opens up great opportunity for future low-cost, high-efficiency photovoltaics.

  13. Ion implanted junctions for silicon space solar cells

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Sanfacon, M. M.; Wolfson, R. G.

    1983-01-01

    This paper reviews the application of ion implantation to emitter and back surface field formation in silicon space solar cells. Experiments based on 2 ohm-cm boron-doped silicon are presented. It is shown that the implantation process is particularly compatible with formation of a high-quality back surface reflector. Large area solar cells with AM0 efficiency greater than 14 percent are reported.

  14. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate

    NASA Astrophysics Data System (ADS)

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-07-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination.

  15. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate

    PubMed Central

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-01-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination. PMID:27435899

  16. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate.

    PubMed

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-07-20

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination.

  17. 2D modeling of silicon based thin film dual and triple junction solar cells

    NASA Astrophysics Data System (ADS)

    Xiao, Y. G.; Uehara, K.; Lestrade, M.; Li, Z. Q.; Li, Z. M. S.

    2009-08-01

    Based on Crosslight APSYS, thin film amorphous Si (a-Si:H)/microcrystalline (μc-Si) dual-junction (DJ) and a- Si:H/amorphous SiGe:H (a-SiGe:H)/μc-Si triple-junction (TJ) solar cells are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves for individual junctions are presented for current matching analyses. The whole DJ and TJ cell I-V curves are also presented and the results are discussed with respect to the top surface ZnO:Al TCO layer affinity. The interface texture effect is modeled with FDTD (finite difference time domain) module and results for top junction are presented. The modeling results give possible clues to achieve high efficiency for DJ and TJ thin film solar cells.

  18. CPV module design optimization for advanced multi-junction solar cell concepts

    NASA Astrophysics Data System (ADS)

    Steiner, Marc; Kiefel, Peter; Siefer, Gerald; Wiesenfarth, Maike; Dimroth, Frank; Krause, Rainer; Gombert, Andreas; Bett, Andreas W.

    2015-09-01

    A network model for multi-junction solar cells has been combined with ray tracing and finite element simulations of a Fresnel lens in order to interpret experimentally derived measurement results. This combined model reveals a good agreement between simulation and measurement for advanced four-junction solar cells under a Fresnel lens when the cell-to-lens distance was varied. Thus, the effect of fill factor drop caused by distributed series resistance losses due to chromatic aberration is well described by this model. Eventually, this model is used to calculate I-V characteristics of a four-junction cell, as well as of a upright metamorphic and lattice-matched triple-junction solar cell under the illumination profile of a Fresnel lens. A significant fill factor drop at distinct cell-to-lens distances was found for all three investigated solar cell types. In this work we discuss how this fill factor drop can be avoided. It is shown that already a halving of the sheet resistance within one of the lateral conduction layer in the solar cell increases the module efficiency significantly.

  19. Light-splitting photovoltaic system utilizing two dual-junction solar cells

    SciTech Connect

    Xiong, Kanglin; Yang, Hui; Lu, Shulong; Dong, Jianrong; Zhou, Taofei; Wang, Rongxin; Jiang, Desheng

    2010-12-15

    There are many difficulties limiting the further development of monolithic multi-junction solar cells, such as the growth of lattice-mismatched material and the current matching constraint. As an alternative approach, the light-splitting photovoltaic system is investigated intensively in different aspects, including the energy loss mechanism and the choice of energy bandgaps of solar cells. Based on the investigation, a two-dual junction system has been implemented employing lattice-matched GaInP/GaAs and InGaAsP/InGaAs cells grown epitaxially on GaAs and InP substrates, respectively. (author)

  20. AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack

    NASA Technical Reports Server (NTRS)

    Dinetta, L. C.; Hannon, M. H.; Cummings, J. R.; Mcneeley, J. B.; Barnett, Allen M.

    1990-01-01

    Free-standing, transparent, tunable bandgap AlxGa1-xAs top solar cells have been fabricated for mechanical attachment in a four terminal tandem stack solar cell. Evaluation of the device results has demonstrated 1.80 eV top solar cells with efficiencies of 18 percent (100 X, and AM0) which would yield stack efficiencies of 31 percent (100 X, AM0) with a silicon bottom cell. When fully developed, the AlxGa1-xAs/Si mechanically-stacked two-junction solar cell concentrator system can provide efficiencies of 36 percent (AM0, 100 X). AlxGa1-xAs top solar cells with bandgaps from 1.66 eV to 2.08 eV have been fabricated. Liquid phase epitaxy (LPE) growth techniques have been used and LPE has been found to yield superior AlxGa1-xAs material when compared to molecular beam epitaxy and metal-organic chemical vapor deposition. It is projected that stack assembly technology will be readily applicable to any mechanically stacked multijunction (MSMJ) system. Development of a wide bandgap top solar cell is the only feasible method for obtaining stack efficiencies greater than 40 percent at AM0. System efficiencies of greater than 40 percent can be realized when the AlGaAs top solar cell is used in a three solar cell mechanical stack.

  1. Investigation of the Carbon Arc Source as an AM0 Solar Simulator for Use in Characterizing Multi-Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Xu, Jianzeng; Woodyward, James R.

    2005-01-01

    The operation of multi-junction solar cells used for production of space power is critically dependent on the spectral irradiance of the illuminating light source. Unlike single-junction cells where the spectral irradiance of the simulator and computational techniques may be used to optimized cell designs, optimization of multi-junction solar cell designs requires a solar simulator with a spectral irradiance that closely matches AM0.

  2. Electrolyte-induced inversion layer Schottky junction solar cells.

    PubMed

    Wadhwa, Pooja; Seol, Gyungseon; Petterson, Maureen K; Guo, Jing; Rinzler, Andrew G

    2011-06-08

    A new type of crystalline silicon solar cell is described. Superficially similar to a photoelectrochemical cell a liquid electrolyte creates a depletion (inversion) layer in an n-type silicon wafer, however no regenerative redox couple is present to ferry charge between the silicon and a counter electrode. Instead holes trapped in the electrolyte-induced inversion layer diffuse along the layer until they come to widely spaced grid lines, where they are extracted. The grid lines consist of a single-walled carbon nanotube film etched to cover only a fraction of the n-Si surface. Modeling and simulation shows the inversion layer to be a natural consequence of the device electrostatics. With electronic gating, recently demonstrated to boost the efficiency in related devices, the cell achieves a power conversion efficiency of 12%, exceeding the efficiency of dye sensitized solar cells.

  3. Single-junction solar cells with the optimum band gap for terrestrial concentrator applications

    DOEpatents

    Wanlass, M.W.

    1994-12-27

    A single-junction solar cell is described having the ideal band gap for terrestrial concentrator applications. Computer modeling studies of single-junction solar cells have shown that the presence of absorption bands in the direct spectrum has the effect of ''pinning'' the optimum band gap for a wide range of operating conditions at a value of 1.14[+-]0.02 eV. Efficiencies exceeding 30% may be possible at high concentration ratios for devices with the ideal band gap. 7 figures.

  4. The Environmental Performance at Low Intensity, Low Temperature (LILT) of High Efficiency Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert; Davis, Gregory; Distefano, Salvador

    2004-01-01

    A number of JPL missions, either active or in the p l d g stages, require the accurate LILT flew intensity - low temperate) climate of triple-junction solar. Although triple ignition LILT performance was reported as recently as 2002, there has been an evolutionary advance in cell technology by both U.S. space cell manufacturers that, for mission design purposes, effectively obsoletes the earlier data. As a result, JPL initiated a program to develop a database for the LILT performance of the new high performance triple junction solar cells. JPL obtained Emcore Advanced triple Juntion CIC assemblies and Spectrolab Ultra Triple Junction CIC assemblies. These cells were tested at temperature-intensity ranges designed to cover applications between 1 and 5.18 AU solar distances. 1 MeV electron irradiation from 25 E14 to 1 El5 w were performed on the cells to evaluate the combined effect of particulate radiation and LILT conditions. The effect of LILT conditions was observed to incur an increase in the variation of cell performances such that at simulted 5.18 AU conditions the average performance was approximately 30% with the best cells measuring between 32 and 34% efficiency. The 30% average efficiency compares with approximately 25% average efficiency measured on earlier technology triple junction solar cells.

  5. Preliminary low temperature electron irradiation of triple junction solar cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2005-01-01

    JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature.

  6. Temperature Dependence of InGaN Dual-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Mesrane, A.; Mahrane, A.; Rahmoune, F.; Oulebsir, A.

    2017-04-01

    The temperature dependence of an InGaN dual-junction solar cell has been investigated. At different temperatures ranging from 300 K to 450 K, the In0.49Ga0.51N/In0.74Ga0.26N dual-junction solar cell and its subcells were simulated and their electrical parameters calculated. The variation of the temperature coefficient of each electrical parameter of the simulated solar cell with temperature was investigated too. Under normalized conditions (AM1.5G, 0.1 W/cm2, 300 K), the temperature coefficient of the short-circuit current density, open-circuit voltage, and conversion efficiency of the In0.49Ga0.51N/In0.74Ga0.26N dual-junction solar cell was +0.0037%/K, -0.1936%/K, and -0.266%/K, respectively. These results demonstrate that InGaN is a promising material for use in dual-junction solar cells for operation at high temperature.

  7. Assessing individual radial junction solar cells over millions on VLS-grown silicon nanowires.

    PubMed

    Yu, Linwei; Rigutti, Lorenzo; Tchernycheva, Maria; Misra, Soumyadeep; Foldyna, Martin; Picardi, Gennaro; Roca i Cabarrocas, Pere

    2013-07-12

    Silicon nanowires (SiNWs) grown on low-cost substrates provide an ideal framework for the monolithic fabrication of radial junction photovoltaics. However, the quality of junction formation over a random matrix of SiNWs, fabricated via a vapor-liquid-solid (VLS) mechanism, has never been assessed in a realistic context. To address this, we probe the current response of individual radial junction solar cells under electron-beam and optical-beam excitations. Excellent current generation from the radial junction units, compared to their planar counterparts, has been recorded, indicating a high junction quality and effective doping in the ultra-thin SiNWs with diameters thinner than 20 nm. Interestingly, we found that the formation of radial junctions by plasma deposition can be quite robust against geometrical disorder and even the crossings of neighboring cell units. These results provide a strong support to the feasibility of building high-quality radial junction solar cells over high-throughput VLS-grown SiNWs on low-cost substrates.

  8. Assessing individual radial junction solar cells over millions on VLS-grown silicon nanowires

    NASA Astrophysics Data System (ADS)

    Yu, Linwei; Rigutti, Lorenzo; Tchernycheva, Maria; Misra, Soumyadeep; Foldyna, Martin; Picardi, Gennaro; Cabarrocas, Pere Roca i.

    2013-07-01

    Silicon nanowires (SiNWs) grown on low-cost substrates provide an ideal framework for the monolithic fabrication of radial junction photovoltaics. However, the quality of junction formation over a random matrix of SiNWs, fabricated via a vapor-liquid-solid (VLS) mechanism, has never been assessed in a realistic context. To address this, we probe the current response of individual radial junction solar cells under electron-beam and optical-beam excitations. Excellent current generation from the radial junction units, compared to their planar counterparts, has been recorded, indicating a high junction quality and effective doping in the ultra-thin SiNWs with diameters thinner than 20 nm. Interestingly, we found that the formation of radial junctions by plasma deposition can be quite robust against geometrical disorder and even the crossings of neighboring cell units. These results provide a strong support to the feasibility of building high-quality radial junction solar cells over high-throughput VLS-grown SiNWs on low-cost substrates.

  9. Photovoltaic characteristics of each subcell evaluated in situ in a triple-junction solar cell

    NASA Astrophysics Data System (ADS)

    Huang, Tzu-Hsuan; Lo, Hao; Lo, Chieh; Wu, Meng-Chyi; Lour, Wen-Shiung

    2016-12-01

    New manufacturing processes were proposed to evaluate important photovoltaic properties of each subcell in an InGaP/InGaAs/Ge triple-junction solar cell. In addition to the triple-junction cell, an InGaAs/Ge double-junction cell and a Ge single-junction cell were also fabricated and employed for evaluation. The key merit of the double-junction cell is that semiconductor layers of forming InGaP top subcell are retained as a dummy top subcell. Thus, the InGaAs middle subcells in both triple- and double-junction cells will receive the same light spectrum. Similarly, the Ge single-junction cell is fabricated with dummy top and middle subcells as light filters. Open-circuit voltage, short-circuit current, conversion efficiency, and current mismatched ratio were measured for evaluating and optimizing each subcell. It is found that Open-circuit voltages are 1.295, 0.967, and 0.212 V for the InGaP, InGaAs, and Ge subcells with temperature coefficients of -2.5, -1.99, and -1.87 mV/°C. Thus the Ge subcell no longer acts a real solar cell at temperature over ∼140 °C. Besides, effect of ambient temperature on short circuit currents of all as-fabricated solar cells is not relevant. The current mismatched ratios are 18.6-20% at temperature ranged from 25 °C to 80 °C. A low efficiency of ∼18.7% is due partly to the poor current match. However, the processing concept proposed is useful as a method of matching currents among the subcells.

  10. Solar energy conversion through the interaction of plasmons with tunnel junctions. Part A: Solar cell analysis. Part B: Photoconductor analysis

    NASA Technical Reports Server (NTRS)

    Welsh, P. E.; Schwartz, R. J.

    1988-01-01

    A solar cell utilizing guided optical waves and tunnel junctions was analyzed to determine its feasibility. From this analysis, it appears that the limits imposed upon conventional multiple cell systems also limit this solar cell. Due to this limitation, it appears that the relative simplicity of the conventional multiple cell systems over the solar cell make the conventional multiple cell systems the more promising candidate for improvement. It was discovered that some superlattice structures studied could be incorporated into an infrared photodetector. This photoconductor appears to be promising as a high speed, sensitive (high D sup star sub BLIP) detector in the wavelength range from 15 to over 100 micrometers.

  11. Comparison of Ge, InGaAs p-n junction solar cell

    NASA Astrophysics Data System (ADS)

    Korun, M.; Navruz, T. S.

    2016-04-01

    In this paper, the effect of material parameters on the efficiency of Ge and InGaAs p-n junction solar cells which are most commonly used as the sub-cell of multi-junction solar cells are investigated and the results due to these two cells are compared. The efficiency of Ge (EG =0.67 eV) solar cell which is easy to manufacture and inexpensive in cost, is compared with the efficiency of InGaAs (EG =0.74 eV) solar cell which is coming with drawback of high production difficulties and cost. The theoretical efficiency limit of Ge and InGaAs solar cells with optimum thickness were determined by using detailed balance model under one sun AM1.5 illumination. Since the band gap values of two cells are close to each other, approximate detailed balance efficiency limits of 16% for InGaAs and 14% for Ge are obtained. When drift-diffusion model is used and the thicknesses and doping concentrations are optimized, the maximum efficiency values are calculated as 13% for InGaAs and 9% for Ge solar cell. For each solar cell external quantum efficiency curves due to wavelength are also sketched and compared.

  12. Organometallic halide perovskite/barium di-silicide thin-film double-junction solar cells

    NASA Astrophysics Data System (ADS)

    Vismara, R.; Isabella, O.; Zeman, M.

    2016-04-01

    Barium di-silicide (BaSi2) is an abundant and inexpensive semiconductor with appealing opto-electrical properties. In this work we show that a 2-μm thick BaSi2-based thin-film solar cell can exhibit an implied photo-current density equal to 41.1 mA/cm2, which is higher than that of a state-of-the-art wafer-based c-Si hetero-junction solar cell. This performance makes BaSi2 an attractive absorber for high-performing thin-film and multi-junction solar cells. In particular, to assess the potential of barium di-silicide, we propose a thin-film double-junction solar cell based on organometallic halide perovskite (CH3NH3PbI3) as top absorber and BaSi2 as bottom absorber. The resulting modelled ultra-thin double-junction CH3NH3PbI3 / BaSi2 (< 2 μm) exhibits an implied total photo-current density equal to 38.65 mA/cm2 (19.84 mA/cm2 top cell, 18.81 mA/cm2 bottom cell) and conversion efficiencies up to 28%.

  13. Theoretical Study and Simulations of an InGaN Dual-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Mesrane, A.; Mahrane, A.; Rahmoune, F.; Oulebsir, A.

    2017-03-01

    This study aims to determine the optimal configuration of the dual-junction InGaN solar cell. Several parameters of the dual-InGaN-junction solar cell have been investigated as the band gap combination and the thicknesses of the layers. Physical models and the optical properties of the In x Ga1- x N according to the indium content have been used. The dual-junction solar cell has been designed and simulated for each chosen band gap combination. The current densities drawn from the sub-cells were matched by adjusting their emitter layers thicknesses. The best conversion efficiency obtained for the optimized dual-junction In0.49Ga0.51N/In0.74Ga0.26N solar cell, under standard conditions, was 34.93% which corresponds to the band gap combination of 1.73 eV/1.13 eV. The short-circuit current density and the open circuit voltage obtained from the tandem cell In0.49Ga0.51N/In0.74Ga0.26N are respectively, 21.3941 mA/cm2 and 1.9144 V. The current mismatch was 0.057%. The effects of the front and back layers thicknesses of the top and bottom cells on the efficiency were also studied. Furthermore, the electrical characteristics of the dual-junction solar cell and its sub-cells were also discussed.

  14. Theoretical Study and Simulations of an InGaN Dual-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Mesrane, A.; Mahrane, A.; Rahmoune, F.; Oulebsir, A.

    2016-12-01

    This study aims to determine the optimal configuration of the dual-junction InGaN solar cell. Several parameters of the dual-InGaN-junction solar cell have been investigated as the band gap combination and the thicknesses of the layers. Physical models and the optical properties of the In x Ga1-x N according to the indium content have been used. The dual-junction solar cell has been designed and simulated for each chosen band gap combination. The current densities drawn from the sub-cells were matched by adjusting their emitter layers thicknesses. The best conversion efficiency obtained for the optimized dual-junction In0.49Ga0.51N/In0.74Ga0.26N solar cell, under standard conditions, was 34.93% which corresponds to the band gap combination of 1.73 eV/1.13 eV. The short-circuit current density and the open circuit voltage obtained from the tandem cell In0.49Ga0.51N/In0.74Ga0.26N are respectively, 21.3941 mA/cm2 and 1.9144 V. The current mismatch was 0.057%. The effects of the front and back layers thicknesses of the top and bottom cells on the efficiency were also studied. Furthermore, the electrical characteristics of the dual-junction solar cell and its sub-cells were also discussed.

  15. The photoelectric characteristics of a few-layer graphene/Si Schottky junction solar cell

    NASA Astrophysics Data System (ADS)

    Ma, Xiying; Gu, Weixia

    2015-10-01

    We present a study of the photovoltaic effects of a graphene/n- Si Schottky junction solar cell. The graphene/Si solar cell was prepared by means of rapid chemical vapor deposition, while the graphene films were grown with a CH4/Ar mixed gas under a constant flow at 950°C and then annealed at 1000°C. It was found that the junction between the graphene film and the n-Si structure played an important role in determining the device performance. An energy conversion efficiency of 2.1% was achieved under an optical illumination of 100 mW. The strong photovoltaic effects of the cell were due to device junction's ability to efficiently generate and separate electron-hole pairs.

  16. Enhanced efficiency of graphene-silicon Schottky junction solar cells by doping with Au nanoparticles

    SciTech Connect

    Liu, X.; Zhang, X. W. Yin, Z. G.; Meng, J. H.; Gao, H. L.; Zhang, L. Q.; Zhao, Y. J.; Wang, H. L.

    2014-11-03

    We have reported a method to enhance the performance of graphene-Si (Gr/Si) Schottky junction solar cells by introducing Au nanoparticles (NPs) onto the monolayer graphene and few-layer graphene. The electron transfer between Au NPs and graphene leads to the increased work function and enhanced electrical conductivity of graphene, resulting in a remarkable improvement of device efficiency. By optimizing the initial thickness of Au layers, the power conversion efficiency of Gr/Si solar cells can be increased by more than three times, with a maximum value of 7.34%. These results show a route for fabricating efficient and stable Gr/Si solar cells.

  17. Cost Trade Between Multi-Junction, Gallium Arsenide, and Silicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Gaddy, Edward M.

    1995-01-01

    Multi-junction (MJ), gallium arsenide (GaAs), and silicon (Si) solar cells have respective test efficiencies of approximately 24%, 18.5% and 14.8%. Multi-junction and gallium arsenide solar cells weigh more than silicon solar 2 cells and cost approximately five times as much per unit power at the cell level. A trade is performed for the TRMM spacecraft to determine which of these cell types would have offered an overall performance and price advantage to the spacecraft. A trade is also performed for the multi-junction cells under the assumption that they will cost over ten times that of silicon cells at the cell level. The trade shows that the TRMM project, less the cost of the instrument, ground systems and mission operations, would spend approximately $552,000 dollars per kilogram to launch and suppon3science in the case of the spacecraft equipped with silicon solar cells. If these cells are changed out for gallium arsenide solar cells, an additional 31 kilograms of science can be launched and serviced at a price of approximately $90 thousand per kilogram. The weight reduction is shown to derive from the smaller area of the array and hence reductions in the weight of the array substrate and supporting structure. ff the silicon solar cells are changed out for multi-junction solar cells, an additional 45 kilograms of science above the silicon base line can be launched and supported at a price of approximately $58,000 per kilogram. The trade shows that even if the multi-junction cells are priced over ten times that of silicon cells, a price that is much higher than projected, that the additional 45 kilograms of science are launched and serviced at $180,000 per kilogram. This is still much less than the original $552,000 per kilogram to launch and service the science. Data and qualitative factors are presented to show that these figures are subject to a great deal of uncertainty. Nonetheless, the benefit of the higher efficiency solar cells for TRMM is far greater

  18. Straw man trade between multi-junction, gallium arsenide, and silicon solar cells

    NASA Technical Reports Server (NTRS)

    Gaddy, Edward M.

    1995-01-01

    Multi-junction (MJ), gallium arsenide (GaAs), and silicon (Si) solar cells have respective test efficiencies of approximately 24%, 18.5% and 14.8%. Multi-junction and gallium arsenide solar cells weigh more than silicon solar cells and cost approximately five times as much per unit power at the cell level. A straw man trade is performed for the TRMM spacecraft to determine which of these cell types would have offered an overall performance and price advantage to the spacecraft. A straw man trade is also performed for the multi-junction cells under the assumption that they will cost over ten times that of silicon cells at the cell level. The trade shows that the TRMM project, less the cost of the instrument, ground systems and mission operations, would spend approximately $552 thousand dollars per kilogram to launch and service science in the case of the spacecraft equipped with silicon solar cells. If these cells are changed out for gallium arsenide solar cells, an additional 31 kilograms of science can be launched and serviced at a price of approximately $90 thousand per kilogram. The weight reduction is shown to derive from the smaller area of the array and hence reductions in the weight of the array substrate and supporting structure. If the silicon solar cells are changed out for multi-junction solar cells, an additional 45 kilograms of science above the silicon base line can be launched and serviced at a price of approximately $58 thousand per kilogram. The trade shows that even if the multi-junction arrays are priced over ten times that of silicon cells, a price that is much higher than projected, that the additional 45 kilograms of science are launched and serviced at $182 thousand per kilogram. This is still much less than original $552 thousand per kilogram to launch and service the science. Data and qualitative factors are presented to show that these figures are subject to a great deal of uncertainty. Nonetheless, the benefit of the higher efficiency

  19. A review on plasma-assisted VLS synthesis of silicon nanowires and radial junction solar cells

    NASA Astrophysics Data System (ADS)

    Misra, Soumyadeep; Yu, Linwei; Chen, Wanghua; Foldyna, Martin; Cabarrocas, Pere Roca i.

    2014-10-01

    Incorporation of nanostructures is a recent trend in the photovoltaic community, aimed at improving light absorption and consequently cell efficiency. In this regard, semiconductor nanowires provide an attractive research platform for a new generation of cost-effective and efficient solar cells. Thanks to their unique geometry, silicon nanowires enhance light trapping and anti-reflection effects by means of multiple scattering between individual nanowires, and by coupling the light into confined eigenmodes over a broad range of the solar spectrum. Moreover, radial junction solar cells built around nanowires decouple the light absorption and carrier collection directions, which allows for a higher internal field and better carrier collection. Thus, arrays of radial junction solar cells bring advantages of high efficiency with reduced material amount. This is particularly attractive for devices based on hydrogenated amorphous and microcrystalline silicon thin films. In this paper, after reviewing different approaches to fabricate silicon nanowires, we focus on nanowires grown using the plasma-assisted vapour-liquid-solid method because of the simplicity and compatibility with current silicon thin-film technology. Their application to a-Si : H based radial junction solar cells has already resulted in ˜8% of stable devices with an absorber layer thickness of only 100 nm. Moreover, current challenges and perspectives such as the use of a microcrystalline silicon absorber are also reviewed.

  20. Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements

    PubMed Central

    Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Toshimitsu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I–V relations of individual subcells without the need for referencing measured I–V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the “balance sheets” of tandem solar cells. PMID:25592484

  1. Enhancing light absorption within the carrier transport length in quantum junction solar cells.

    PubMed

    Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene

    2015-09-10

    Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31  mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells.

  2. AlGaInP/Ge double-junction solar cell with Sb incorporation directly used for lattice-matched five-junction solar cell application

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Wang, Qing; Zhang, Xiaobin; Chen, Bingzhen; Wu, Bo; Ma, Difei; Zhang, Lu; Wang, Zhiyong

    2017-02-01

    AlGaInP is a prospectively valuable material for high-efficiency lattice-matched tandem AlGaInP/AlGaInAs/GaAs/GaInNAs/Ge (2.05/1.7/1.4/1.0/0.7 eV) five-junction solar cells. We examine the optical properties of AlGaInP materials with trimethylantimony (TMSb) incorporated at various flow speeds. Then, we apply Al0.1GaInP with TMSb incorporated at 15.6 µmol/min, whose band gap is 2.04 eV, to the fabrication of an AlGaInP/Ge double-junction (DJ) solar cell. Moreover, we analyze the photovoltaic current density–voltage (J–V) characteristics, external quantum efficiencies (EQEs), and internal quantum efficiencies (IQEs) of DJ cells under a 1-sun AM0 spectrum. As elsewhere, Sb incorporation improves the crystal quality of AlGaInP and the fill factor of the DJ solar cell; on the other hand, it increases the band gap of AlGaInP. Al0.08GaInP with Sb incorporation shows the same absorption edge of EQE as Al0.1GaInP without Sb incorporation, and J sc increases approximately by 15.3% owing to the reduction of 2% Al composition.

  3. Investigations To Characterize Multi-Junction Solar Cells In The Stratosphere Using Low-Cost Balloon And Communication Technologies

    NASA Technical Reports Server (NTRS)

    Bowe, Glenroy A.; Wang, Qianghua; Woodyard, James R.; Johnston, Richard R.; Brown, William J.

    2005-01-01

    The use of current balloon, control and communication technologies to test multi-junction solar sell in the stratosphere to achieve near AMO conditions have been investigated. The design criteria for the technologies are that they be reliable, low cost and readily available. Progress is reported on a program to design, launch, fly and retrieve payloads dedicated to testing multi-junction solar cells.

  4. Progress toward the development of dual junction GaAs/Ge solar cells

    NASA Technical Reports Server (NTRS)

    Lillington, D. R.; Krut, D. D.; Cavicchi, B. T.; Ralph, E.; Chung, M.

    1991-01-01

    Large area GaAs/Ge cells offer substantial promise for increasing the power output from existing silicon solar array designs and for providing an enabled technology for missions hitherto impossible using silicon. Single junction GaAs/Ge cells offer substantial advantages in both size, weight, and cost compared to GaAs cells but the efficiency is limited to approximately 19.2 to 20 percent AMO. The thermal absorptance of GaAs/Ge cells is also worse than GaAs/GaAs cells (0.88 vs 0.81 typ.) due to the absorption in the Ge substrate. On the other hand dual junction GaAs/Ge cells offer efficiencies up to ultimately 24 percent AMO in sizes up to 8 x 8 cm but there are still technological issues remaining to achieve current matching in the GaAs and Ge cells. This can be achieved through tuned antireflection (AR) coatings, improved quality of the GaAs growth, improved quality Ge wafers and the use of a Back Surface Field (BSF)/Back Surface Reflector (BSR) in the Ge cell. Although the temperature coefficients of efficiency and voltage are higher for dual junction GaAs/Ge cells, it has been shown elsewhere that for typical 28 C cell efficiencies of 22 percent (dual junction) vs 18.5 percent (single junction) there is a positive power tradeoff up to temperatures as high as 120 C. Due to the potential ease of fabrication of GaAs/Ge dual junction cells there is likely to be only a small cost differential compared to single junction cells.

  5. Straw man trade between multi-junction, gallium arsenide, and silicon solar cells

    SciTech Connect

    Gaddy, E.M.

    1995-10-01

    Multi-junction (MJ), gallium arsenide (GaAs), and silicon (Si) solar cells have respective test efficiencies of approximately 24%, 18.5% and 14.8%. Multi-junction and gallium arsenide solar cells weigh more than silicon solar cells and cost approximately five times as much per unit power at the cell level. A straw man trade is performed for the TRMM spacecraft to determine which of these cell types would have offered an overall performance and price advantage to the spacecraft. A straw man trade is also performed for the multi-junction cells under the assumption that they will cost over ten times that of silicon cells at the cell level. The trade shows that the TRMM project, less the cost of the instrument, ground systems and mission operations, would spend approximately $552 thousand dollars per kilogram to launch and service science in the case of the spacecraft equipped with silicon solar cells. If these cells are changed out for gallium arsenide solar cells, an additional 31 kilograms of science can be launched and serviced at a price of approximately $90 thousand per kilogram. The weight reduction is shown to derive from the smaller area of the array and hence reductions in the weight of the array substrate and supporting structure. If the silicon solar cells are changed out for multi-junction solar cells, an additional 45 kilograms of science above the silicon base line can be launched and serviced at a price of approximately $58 thousand per kilogram. The trade shows that even if the multi-junction arrays are priced over ten times that of silicon cells, a price that is much higher than projected, that the additional 45 kilograms of science are launched and serviced at $182 thousand per kilogram. This is still much less than original $552 thousand per kilogram to launch and service the science. Data and qualitative factors are presented to show that these figures are subject to a great deal of uncertainty.

  6. Enhanced Conversion Efficiency of III–V Triple-junction Solar Cells with Graphene Quantum Dots

    PubMed Central

    Lin, Tzu-Neng; Santiago, Svette Reina Merden S.; Zheng, Jie-An; Chao, Yu-Chiang; Yuan, Chi-Tsu; Shen, Ji-Lin; Wu, Chih-Hung; Lin, Cheng- An J.; Liu, Wei-Ren; Cheng, Ming-Chiang; Chou, Wu-Ching

    2016-01-01

    Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell. PMID:27982073

  7. Silicon-core glass fibres as microwire radial-junction solar cells.

    PubMed

    Martinsen, F A; Smeltzer, B K; Nord, M; Hawkins, T; Ballato, J; Gibson, U J

    2014-09-04

    Vertically aligned radial-junction solar cell designs offer potential improvements over planar geometries, as carrier generation occurs close to the junction for all absorption depths, but most production methods still require a single crystal substrate. Here, we report on the fabrication of such solar cells from polycrystalline, low purity (99.98%) p-type silicon starting material, formed into silicon core, silica sheath fibres using bulk glass draw techniques. Short segments were cut from the fibres, and the silica was etched from one side, which exposed the core and formed a conical cavity around it. We then used vapour deposition techniques to create p-i-n junction solar cells. Prototype cells formed from single fibres have shown conversion efficiencies up to 3.6%, despite the low purity of the starting material. This fabrication method has the potential to reduce the energy cost and the silicon volume required for solar cell production. Simulations were performed to investigate the potential of the conical cavity around the silicon core for light collection. Absorption of over 90% of the incident light was predicted, over a wide range of wavelengths, using these structures in combination with a 10% volume fraction of silicon.

  8. Enhanced Conversion Efficiency of III-V Triple-junction Solar Cells with Graphene Quantum Dots.

    PubMed

    Lin, Tzu-Neng; Santiago, Svette Reina Merden S; Zheng, Jie-An; Chao, Yu-Chiang; Yuan, Chi-Tsu; Shen, Ji-Lin; Wu, Chih-Hung; Lin, Cheng-An J; Liu, Wei-Ren; Cheng, Ming-Chiang; Chou, Wu-Ching

    2016-12-16

    Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell.

  9. Enhanced Conversion Efficiency of III–V Triple-junction Solar Cells with Graphene Quantum Dots

    NASA Astrophysics Data System (ADS)

    Lin, Tzu-Neng; Santiago, Svette Reina Merden S.; Zheng, Jie-An; Chao, Yu-Chiang; Yuan, Chi-Tsu; Shen, Ji-Lin; Wu, Chih-Hung; Lin, Cheng-An J.; Liu, Wei-Ren; Cheng, Ming-Chiang; Chou, Wu-Ching

    2016-12-01

    Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell.

  10. Design optimization of thin-film/wafer-based tandem junction solar cells using analytical modeling

    NASA Astrophysics Data System (ADS)

    Davidson, Lauren; Toor, Fatima

    2016-03-01

    Several research groups are developing solar cells of varying designs and materials that are high efficiency as well as cost competitive with the single junction silicon (Si) solar cells commercially produced today. One of these solar cell designs is a tandem junction solar cell comprised of perovskite (CH3NH3PbI3) and silicon (Si). Loper et al.1 was able to create a 13.4% efficient tandem cell using a perovskite top cell and a Si bottom cell, and researchers are confident that the perovskite/Si tandem cell can be optimized in order to reach higher efficiencies without introducing expensive manufacturing processes. However, there are currently no commercially available software capable of modeling a tandem cell that is based on a thin-film based bottom cell and a wafer-based top cell. While PC1D2 and SCAPS3 are able to model tandem cells comprised solely of thin-film absorbers or solely of wafer-based absorbers, they result in convergence errors if a thin-film/wafer-based tandem cell, such as the perovskite/ Si cell, is modeled. The Matlab-based analytical model presented in this work is capable of modeling a thin-film/wafer-based tandem solar cell. The model allows a user to adjust the top and bottom cell parameters, such as reflectivity, material bandgaps, donor and acceptor densities, and material thicknesses, in order to optimize the short circuit current, open circuit voltage, and quantum efficiency of the tandem solar cell. Using the Matlab-based analytical model, we were able optimize a perovskite/Si tandem cell with an efficiency greater than 30%.

  11. An ARC less InGaP/GaAs DJ solar cell with hetero tunnel junction

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Nayak, P. P.; Mishra, G. P.

    2016-07-01

    Multi junction solar cell has not achieved an optimum performance yet. To acquire more conversion efficiency research on multi junction solar cell are in progress. In this work we have proposed a dual junction solar cell with conversion efficiency of 43.603%. Mainly the focus is given on the tunnel diode, window layer and back surface field (BSF) layer of the cell, as all of them plays important role on the cell performance. Here we have designed a hetero InGaP/GaAs tunnel diode which makes tunnel diode more transparent to the bottom cell as well as reduces the recombination at the interfaces. The thickness of the window and BSF layer are optimized to achieve higher conversion efficiency. The simulation is carried out using Silvaco ATLAS TCAD under 1000 sun of AM1.5G spectrum. Different performance parameters of the cell like short circuit current density (Jsc), open circuit voltage (Voc), external quantum efficiency (EQE), fill factor (FF), conversion efficiency (η), spectral response and photogeneration rate of the cell are examined and compared with previously reported literatures. For the proposed model a Voc of 2.7043 V, Jsc of 1898.52 mA/cm2, FF of 88.88% and η of 43.6% are obtained.

  12. Porous copper zinc tin sulfide thin film as photocathode for double junction photoelectrochemical solar cells.

    PubMed

    Dai, Pengcheng; Zhang, Guan; Chen, Yuncheng; Jiang, Hechun; Feng, Zhenyu; Lin, Zhaojun; Zhan, Jinhua

    2012-03-21

    Porous copper zinc tin sulfide (CZTS) thin film was prepared via a solvothermal approach. Compared with conventional dye-sensitized solar cells (DSSCs), double junction photoelectrochemical cells using dye-sensitized n-type TiO(2) (DS-TiO(2)) as the photoanode and porous p-type CZTS film as the photocathode shows an increased short circuit current, external quantum efficiency and power conversion efficiency.

  13. EMCORE four-junction inverted metamorphic solar cell development

    NASA Astrophysics Data System (ADS)

    Miller, Nate; Patel, Pravin; Struempel, Claudia; Kerestes, Chris; Aiken, Dan; Sharps, Paul

    2014-09-01

    EMCORE grown and tested four-junction terrestrial concentrator inverted metamorphic multijunction (CIMM) devices have been demonstrated with internally measured typical efficiencies of ˜44% and peak efficiencies as high as ˜47%, which are in the realm of world record performance. Improved internal testing as well as external validation by NREL are in progress.

  14. 1.00 MeV proton radiation resistance studies of single-junction and single gap dual-junction amorphous-silicon alloy solar cells

    NASA Technical Reports Server (NTRS)

    Abdulaziz, Salman; Payson, J. S.; Li, Yang; Woodyard, James R.

    1990-01-01

    A comparative study of the radiation resistance of a-Si:H and a-SiGe:H single-junction and a-Si:H dual-junction solar cells was conducted. The cells were irradiated with 1.00-MeV protons with fluences of 1.0 x 10 to the 14th, 5.0 x 10 to the 14th and 1.0 x 10 to the 15th/sq cm and characterized using I-V and quantum efficiency measurements. The radiation resistance of single-junction cells cannot be used to explain the behavior of dual-junction cells at a fluence of 1.0 x 10 to the 15th/sq cm. The a-Si H single-junction cells degraded the least of the three cells; a-SiGe:H single-junction cells showed the largest reduction in short-circuit current, while a-Si:H dual-junction cells exhibited the largest degradation in the open-circuit voltage. The quantum efficiency of the cells degraded more in the red part of the spectrum; the bottom junction degrades first in dual-junction cells.

  15. Multi-junction-solar-cell designs and characterizations based on detailed-balance principle and luminescence yields

    NASA Astrophysics Data System (ADS)

    Akiyama, Hidefumi; Zhu, Lin; Yoshita, Masahiro; Kim, Changsu; Chen, Shaoqiang; Mochizuki, Toshimitsu; Kanemitsu, Yoshihiko

    2015-03-01

    We developed a straightforward method based on detailed balance relations to analyze individual subcells in multi-junction solar cells via measuring absolute electroluminescence quantum yields. This method was applied to characterization of a InGaP/GaAs/Ge 3-junction solar cell for satellite use. In addition to subcell I-V characteristics and internal luminescence yields, we derived balance sheets of energy and carriers, which revealed respective subcell contributions of radiative and nonradiative recombination losses, junction loss, and luminescence coupling. These results provide important diagnosis and feedback to fabrications. We calculated conversion-efficiency limit and optimized bandgap energy in 2-, 3-, and 4-junction tandem solar cells, including finite values of sub-cell internal luminescence quantum yields to account for realistic material qualities in sub-cells. With reference to the measured internal luminescence quantum yields, the theoretical results provide realistic targets of efficiency limits and improved design principles of practical tandem solar cells.

  16. Development and fabrication of a solar cell junction processing system

    NASA Astrophysics Data System (ADS)

    Giesling, R.

    1981-07-01

    Modifications to the ground plane, to insure a good electrical return path during the pulse discharge, were made using a ring of beryllium copper finger stock attached to the underside of the aluminum ground plate. Experiments on annealing of wafers with ion implantation damage continued. The entire surface of 100 mm diameter wafers were annealed by one pulse for the standard implant (10 keV, phosphorus, 2x10 to the 15th power ions/sq cm). While samples are being fabricated into solar cells for electrical characterization, work is continuing on improvement of the electron beam uniformity and the optimization of the diode parameters. The engineering design was completed and the manufacturing detail drawings were released for fabrication. Assembly of the subcomponents for the exit and entrance locks is almost complete. These components include the cassettes, the indexing mechanisms, main doors, and wafer carrier transfer modules. The 'Y' track and three phase transition track sections are under final assembly and test.

  17. Development and fabrication of a solar cell junction processing system

    NASA Technical Reports Server (NTRS)

    Giesling, R.

    1981-01-01

    Modifications to the ground plane, to insure a good electrical return path during the pulse discharge, were made using a ring of beryllium copper finger stock attached to the underside of the aluminum ground plate. Experiments on annealing of wafers with ion implantation damage continued. The entire surface of 100 mm diameter wafers were annealed by one pulse for the standard implant (10 keV, phosphorus, 2x10 to the 15th power ions/sq cm). While samples are being fabricated into solar cells for electrical characterization, work is continuing on improvement of the electron beam uniformity and the optimization of the diode parameters. The engineering design was completed and the manufacturing detail drawings were released for fabrication. Assembly of the subcomponents for the exit and entrance locks is almost complete. These components include the cassettes, the indexing mechanisms, main doors, and wafer carrier transfer modules. The 'Y' track and three phase transition track sections are under final assembly and test.

  18. Characterization and modeling of radiation damages via internal radiative efficiency in multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Yoshita, Masahiro; Nakamura, Tetsuya; Imaizumi, Mitsuru; Kim, Changsu; Mochizuki, Toshimitsu; Chen, Shaoqiang; Kanemitsu, Yoshihiko; Akiyama, Hidefumi

    2016-03-01

    In order to understand the radiation effects in space-used multi-junction solar cells, we characterized degradations of internal radiative efficiency (ηint i ) in respective subcells in InGaP/GaAs double-junction solar cells after 1-MeV electron irradiations with different electrons fluences (Φ) via absolute electroluminescence (EL) measurements, because ηint i purely represents material-quality change due to radiation damage, independently from cell structures. We analyzed the degradation of ηint i under different Φ and found that the data of ηint i versus Φ in moderate and high Φ regions are very similar and almost independent of subcell materials, while the difference in beginning-of-life qualities of InGaP and GaAs materials causes dominant difference in sub-cell sensitivity to the low radiation damages. Finally, a simple model was proposed to explain the mechanism in degradation of ηint i, and also well explained the degradation behavior in open-circuit voltage for these multi-junction solar cells.

  19. Morphology, properties, and performance of electrodeposited n-CdSe in liquid junction solar cells

    SciTech Connect

    Tomkiewicz, M.; Ling, I.; Parsons, W.S.

    1982-09-01

    The authors describe the mechanisms for galvanostatic electrodeposition of CdSe in terms of competition between chemical reactions that lead to Se formation and electrochemical reduction of Se as polyselenide, at the interfaces between selenium and selenide. This mechanism leads to a cauliflower morphology for the resulting film. This morphology is ideal for a photoanode in the liquid junction solar cell configuration, and the authors describe the performance of such an electrode. In spite of the unique morphology, solid-state properties of the film can be evaluated and the methodology for these evaluations is presented. The performance of the liquid junction solar cells is limited by the dark current and the dielectric properties of the material. The authors also describe the effects of metal ions such as Zn/sup +2/, Ru/sup +3/, and Ga/sup +3/ on the various electrode properties.

  20. Triple-Junction Hybrid Tandem Solar Cells with Amorphous Silicon and Polymer-Fullerene Blends

    PubMed Central

    Kim, Taehee; Kim, Hyeok; Park, Jinjoo; Kim, Hyungchae; Yoon, Youngwoon; Kim, Sung-Min; Shin, Chonghoon; Jung, Heesuk; Kim, Inho; Jeong, Doo Seok; Kim, Honggon; Kim, Jin Young; Kim, BongSoo; Ko, Min Jae; Son, Hae Jung; Kim, Changsoon; Yi, Junsin; Han, Seunghee; Lee, Doh-Kwon

    2014-01-01

    Organic-inorganic hybrid tandem solar cells attract a considerable amount of attention due to their potential for realizing high efficiency photovoltaic devices at a low cost. Here, highly efficient triple-junction (TJ) hybrid tandem solar cells consisting of a double-junction (DJ) amorphous silicon (a-Si) cell and an organic photovoltaic (OPV) rear cell were developed. In order to design the TJ device in a logical manner, a simulation was carried out based on optical absorption and internal quantum efficiency. In the TJ architecture, the high-energy photons were utilized in a more efficient way than in the previously reported a-Si/OPV DJ devices, leading to a significant improvement in the overall efficiency by means of a voltage gain. The interface engineering such as tin-doped In2O3 deposition as an interlayer and its UV-ozone treatment resulted in the further improvement in the performance of the TJ solar cells. As a result, a power conversion efficiency of 7.81% was achieved with an open-circuit voltage of 2.35 V. The wavelength-resolved absorption profile provides deeper insight into the detailed optical response of the TJ hybrid solar cells. PMID:25412648

  1. An optimized efficient dual junction InGaN/CIGS solar cell: A numerical simulation

    NASA Astrophysics Data System (ADS)

    Farhadi, Bita; Naseri, Mosayeb

    2016-08-01

    The photovoltaic performance of an efficient double junction InGaN/CIGS solar cell including a CdS antireflector top cover layer is studied using Silvaco ATLAS software. In this study, to gain a desired structure, the different design parameters, including the CIGS various band gaps, the doping concentration and the thickness of CdS layer are optimized. The simulation indicates that under current matching condition, an optimum efficiency of 40.42% is achieved.

  2. Single-junction polymer solar cells exceeding 10% power conversion efficiency.

    PubMed

    Chen, Jing-De; Cui, Chaohua; Li, Yan-Qing; Zhou, Lei; Ou, Qing-Dong; Li, Chi; Li, Yongfang; Tang, Jian-Xin

    2015-02-01

    A single-junction polymer solar cell with an efficiency of 10.1% is demonstrated by using deterministic aperiodic nanostructures for broadband light harvesting with optimum charge extraction. The performance enhancement is ascribed to the self-enhanced absorption due to collective effects, including pattern-induced anti-reflection and light scattering, as well as surface plasmonic resonance, together with a minimized recombination probability.

  3. Nb2O5 as a new electron transport layer for double junction polymer solar cells.

    PubMed

    Siddiki, Mahbube K; Venkatesan, Swaminathan; Qiao, Qiquan

    2012-04-14

    Nb(2)O(5) as a new electron transport layer (ETL) was used for double junction polymer solar cells. The Nb(2)O(5) ETL was prepared by spin coating a Nb(2)O(5) sol-gel solution onto the active layer of the optical front subcell. The double junction devices using Nb(2)O(5) ETL exhibit an open circuit voltage (V(oc)) of 1.30 V, which is close to the sum of the s of the individual subcells. The current density-voltage (J-V) simulation showed that the double junction device performance using Nb(2)O(5) as ETL could be significantly increased by reducing the series resistance (R(se)) and matching the current densities of the individual subcells.

  4. Modeling Laser Effects on Multi-Junction Solar Cells Using Silvaco ATLAS Software for Spacecraft Power Beaming Applications

    DTIC Science & Technology

    2010-06-01

    devised was meant to achieve the highest efficiency of the solar cell while maintaining the same power output. In a perfect world the system would...CHAMPION CELL - 36.28% Efficiency !! #This model is an explicit InGaP/ GaAs /Ge Triple Junction solar cell with Tunnel Junction KATO OPTM 0.82InGaP...the same output of the cell as experienced under solar illumination, thereby replacing the sun. The original cell boasted 36.29% efficiency under

  5. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures

    NASA Astrophysics Data System (ADS)

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-07-01

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the

  6. Development and fabrication of a solar cell junction processing system. Quarterly report No. 2, July 1980

    SciTech Connect

    Siesling, R.

    1980-07-01

    The basic objectives of the program are the following: (1) to design, develop, construct and deliver a junction processing system which will be capable of producing solar cell junctions by means of ion implantation followed by pulsed electron beam annealing; (2) to include in the system a wafer transport mechanism capable of transferring 4-inch-diameter wafers into and out of the vacuum chamber where the ion implantation and pulsed electron beam annealing processes take place; (3) to integrate, test and demonstrate the system prior to its delivery to JPL along with detailed operating and maintenance manuals; and (4) to estimate component lifetimes and costs, as necessary for the contract, for the performance of comprehensive analyses in accordance with the Solar Array Manufacturing Industry Costing Standards (SAMICS). Under this contract the automated junction formation equipment to be developed involves a new system design incorporating a modified, government-owned, JPL-controlled ion implanter into a Spire-developed pulsed electron beam annealer and wafer transport system. When modified, the ion implanter will deliver a 16 mA beam of /sup 31/P/sup +/ ions with a fluence of 2.5 x 10/sup 15/ ions per square centimeter at an energy of 10 keV. The throughput design goal rate for the junction processor is 10/sup 7/ four-inch-diameter wafers per year.

  7. Thermal stability of titanium nitride for shallow junction solar cell contacts

    NASA Astrophysics Data System (ADS)

    Cheung, N. W.; von Seefeld, H.; Nicolet, M.-A.; Ho, F.; Iles, P.

    1981-06-01

    To demonstrate the thermal stability of titanium nitride as a high-temperature diffusion barrier, the TiN-Ti-Ag metallization scheme has been tested on shallow-junction (2000 A) Si solar cells. Electrical measurements on reference samples with the Ti-Ag metallization scheme show serious degradation after a 600 C, 10-min annealing. With the TiN-Ti-Ag scheme, no degradation of cell performance is observed after the same heat treatment if the TiN layer is equal to or greater than 1700 A. The glass encapsulation of cells by electrostatic bonding requires such a heat treatment.

  8. Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

    1987-01-01

    Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

  9. Diffused junction p(+)-n solar cells in bulk GaAs. II - Device characterization and modelling

    NASA Technical Reports Server (NTRS)

    Keeney, R.; Sundaram, L. M. G.; Rode, H.; Bhat, I.; Ghandhi, S. K.; Borrego, J. M.

    1984-01-01

    The photovoltaic characteristics of p(+)-n junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are presented in detail. Quantum efficiency measurements were analyzed and compared to computer simulations of the cell structure in order to determine material parameters such as diffusion length, surface recombination velocity and junction depth. From the results obtained it is projected that proper optimization of the cell parameters can increase the efficiency of the cells to close to 20 percent.

  10. New implantation techniques for improved solar cell junctions

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Bunker, S. N.

    1982-01-01

    Ion implantation techniques offering improved cell performance and reduced cost have been studied. These techniques include non-mass-analyzed phosphorus implantation, argon implantation gettering, and low temperature boron annealing. It is found that cells produced by non-mass-analyzed implantation perform as well as mass-analyzed controls, and that the cell performance is largely independent of process parameters. A study of argon implantation gettering shows no improvement over non-gettered controls. Results of low temperature boron annealing experiments are presented.

  11. High band gap 2-6 and 3-5 tunneling junctions for silicon multijunction solar cells

    NASA Technical Reports Server (NTRS)

    Daud, Taher (Inventor); Kachare, Akaram H. (Inventor)

    1986-01-01

    A multijunction silicon solar cell of high efficiency is provided by providing a tunnel junction between the solar cell junctions to connect them in series. The tunnel junction is comprised of p+ and n+ layers of high band gap 3-5 or 2-6 semiconductor materials that match the lattice structure of silicon, such as GaP (band gap 2.24 eV) or ZnS (band gap 3.6 eV). Each of which has a perfect lattice match with silicon to avoid defects normally associated with lattice mismatch.

  12. A 2-terminal perovskite/silicon multijunction solar cell enabled by a silicon tunnel junction

    SciTech Connect

    Mailoa, Jonathan P.; Bailie, Colin D.; Johlin, Eric C.; Hoke, Eric T.; Akey, Austin J.; Nguyen, William H.; McGehee, Michael D.; Buonassisi, Tonio

    2015-03-24

    With the advent of efficient high-bandgap metal-halide perovskite photovoltaics, an opportunity exists to make perovskite/silicon tandem solar cells. We fabricate a monolithic tandem by developing a silicon-based interband tunnel junction that facilitates majority-carrier charge recombination between the perovskite and silicon sub-cells. We demonstrate a 1 cm2 2-terminal monolithic perovskite/silicon multijunction solar cell with a VOC as high as 1.65 V. As a result, we achieve a stable 13.7% power conversion efficiency with the perovskite as the current-limiting sub-cell, and identify key challenges for this device architecture to reach efficiencies over 25%.

  13. A 2-terminal perovskite/silicon multijunction solar cell enabled by a silicon tunnel junction

    DOE PAGES

    Mailoa, Jonathan P.; Bailie, Colin D.; Johlin, Eric C.; ...

    2015-03-24

    With the advent of efficient high-bandgap metal-halide perovskite photovoltaics, an opportunity exists to make perovskite/silicon tandem solar cells. We fabricate a monolithic tandem by developing a silicon-based interband tunnel junction that facilitates majority-carrier charge recombination between the perovskite and silicon sub-cells. We demonstrate a 1 cm2 2-terminal monolithic perovskite/silicon multijunction solar cell with a VOC as high as 1.65 V. As a result, we achieve a stable 13.7% power conversion efficiency with the perovskite as the current-limiting sub-cell, and identify key challenges for this device architecture to reach efficiencies over 25%.

  14. Results from an International Measurement Round Robin of III-V Triple Junction Solar Cells under Air Mass Zero

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Scheiman, Chris; Goodbody, Chris; Baur, Carsten; Sharps, Paul; Imaizumi, Mitsuru; Yoo, Henry; Sahlstrom, Ted; Walters, Robert; Lorentzen, Justin; Nocerino, John; Khan, Osman; Cravens, Robert; Valles, Juan; Toporow, Chantal; Gomez, Trinidad,; Bazan, Loreto Pazos; Bailey, Sheila

    2006-01-01

    This paper reports the results of an international measurement round robin of monolithic, triple-junction, GaInP/GaAs/Ge space solar cells. Eight laboratories representing national labs, solar cell vendors and space solar cell consumers, measured cells using in-house reference cells and compared those results to measurements made where each lab used the same set of reference cells. The results show that most of the discrepancy between laboratories is likely due to the quality of the standard cells rather than the measurement system or solar simulator used.

  15. A comparison of light-harvesting performance of silicon nanocones and nanowires for radial-junction solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfeng; Li, Meicheng; Fu, Pengfei; Li, Ruike; Song, Dandan; Shen, Chao; Zhao, Yan

    2015-06-01

    Silicon nanorod based radial-junction solar cells are competitive alternatives to traditional planar silicon solar cells. In various silicon nanorods, nanocone is always considered to be better than nanowire in light-absorption. Nevertheless, we find that this notion isn’t absolutely correct. Silicon nanocone is indeed significantly superior over nanowire in light-concentration due to its continuous diameters, and thus resonant wavelengths excited. However, the concentrated light can’t be effectively absorbed and converted to photogenerated carriers, since its propagation path in silicon nanocone is shorter than that in nanowire. The results provide critical clues for the design of silicon nanorod based radial-junction solar cells.

  16. A comparison of light-harvesting performance of silicon nanocones and nanowires for radial-junction solar cells.

    PubMed

    Li, Yingfeng; Li, Meicheng; Fu, Pengfei; Li, Ruike; Song, Dandan; Shen, Chao; Zhao, Yan

    2015-06-26

    Silicon nanorod based radial-junction solar cells are competitive alternatives to traditional planar silicon solar cells. In various silicon nanorods, nanocone is always considered to be better than nanowire in light-absorption. Nevertheless, we find that this notion isn't absolutely correct. Silicon nanocone is indeed significantly superior over nanowire in light-concentration due to its continuous diameters, and thus resonant wavelengths excited. However, the concentrated light can't be effectively absorbed and converted to photogenerated carriers, since its propagation path in silicon nanocone is shorter than that in nanowire. The results provide critical clues for the design of silicon nanorod based radial-junction solar cells.

  17. InP-based composite substrates for four junction concentrator solar cells

    NASA Astrophysics Data System (ADS)

    Tauzin, Aurélie; Lagoutte, Emmanuelle; Salvetat, Thierry; Guelfucci, Jude; Bogumilowicz, Yann; Imbert, Bruno; Fournel, Frank; Reboh, Shay; Luce, Flavia Piegas; Lecouvey, Christophe; Chaira, Tarik; Carron, Véronique; Moriceau, Hubert; Duvernay, Julien; Signamarcheix, Thomas; Drazek, Charlotte; Charles-Alfred, Cédric; Ghyselen, Bruno; Guiot, Eric; Tibbits, Thomas; Beutel, Paul; Dimroth, Frank

    2015-09-01

    A photovoltaics conversion efficiency of 46% at 508 suns concentration was recently demonstrated with a four-junction solar cell consisting in a GaAs-based top tandem cell transferred onto an InP-based bottom tandem cell, by means of wafer bonding. We have successfully produced and characterized different InPOS (for InP-On-Substrate) composite substrates, that could advantageously replace fragile and expensive InP bulk wafers for the growth of the bottom tandem cell. The InPOS composite substrates include a thin top InP layer with thickness below 1µm, transferred onto a host substrate using the Smart Cut™ layer transfer technology. We developed InP-On-GaAs, InP-On-Ge and InP-On-Sapphire substrates with surface and crystal qualities similar to the InP bulk ones. A low electrical resistance of 1.4mΩ.cm² was measured along the InP transferred layer and the bonding interface. An epitaxial bottom tandem cell was grown on an InPOS substrate, and the corresponding PL behavior was found identical to that of cells grown on InP bulk reference. The InP-based composite substrates are then very well suited for the fabrication of advanced devices like four-junction solar cells.

  18. Equivalent electron fluence for space qualification of shallow junction heteroface GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Stock, L. V.

    1984-01-01

    It is desirable to perform qualification tests prior to deployment of solar cells in space power applications. Such test procedures are complicated by the complex mixture of differing radiation components in space which are difficult to simulate in ground test facilities. Although it has been shown that an equivalent electron fluence ratio cannot be uniquely defined for monoenergetic proton exposure of GaAs shallow junction cells, an equivalent electron fluence test can be defined for common spectral components of protons found in space. Equivalent electron fluence levels for the geosynchronous environment are presented.

  19. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures.

    PubMed

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-08-14

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm(2) exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm(-2) because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.

  20. Direct-bonded four-junction GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Jingman, Shen; Lijie, Sun; Kaijian, Chen; Wei, Zhang; Xunchun, Wang

    2015-06-01

    Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fabricating III-V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the GaInP/GaAs and InGaAsP/InGaAs subcells, the bonded GaAs/InP heterojunction must be a highly conductive ohmic junction or a tunnel junction. Three types of bonding interfaces were designed by tuning the conduction type and doping elements of GaAs and InP. The electrical properties of p-GaAs (Zn doped)/n-InP (Si doped), p-GaAs (C doped)/n-InP (Si doped) and n-GaAs (Si doped)/n-InP (Si doped) bonded heterojunctions were analyzed from the I-V characteristics. The wafer bonding process was investigated by improving the quality of the sample surface and optimizing the bonding parameters such as bonding temperature, bonding pressure, bonding time and so on. Finally, GaInP/GaAs/InGaAsP/InGaAs 4-junction solar cells have been prepared by a direct wafer bonding technique with the high efficiency of 34.14% at the AM0 condition (1 Sun). Project supported by the Shanghai Rising-Star Program (No. 14QB1402800).

  1. Radial junction amorphous silicon solar cells on PECVD-grown silicon nanowires.

    PubMed

    Yu, Linwei; O'Donnell, Benedict; Foldyna, Martin; Roca i Cabarrocas, Pere

    2012-05-17

    Constructing radial junction hydrogenated amorphous silicon (a-Si:H) solar cells on top of silicon nanowires (SiNWs) represents a promising approach towards high performance and cost-effective thin film photovoltaics. We here develop an all-in situ strategy to grow SiNWs, via a vapour-liquid-solid (VLS) mechanism on top of ZnO-coated glass substrate, in a plasma-enhanced chemical vapour deposition (PECVD) reactor. Controlling the distribution of indium catalyst drops allows us to tailor the as-grown SiNW arrays into suitable size and density, which in turn results in both a sufficient light trapping effect and a suitable arrangement allowing for conformal coverage of SiNWs by subsequent a-Si:H layers. We then demonstrate the fabrication of radial junction solar cells and carry on a parametric study designed to shed light on the absorption and quantum efficiency response, as functions of the intrinsic a-Si:H layer thickness and the density of SiNWs. These results lay a solid foundation for future structural optimization and performance ramp-up of the radial junction thin film a-Si:H photovoltaics.

  2. Realization of GaInP/Si Dual-Junction Solar Cells With 29.8% 1-Sun Efficiency

    SciTech Connect

    Essig, Stephanie; Steiner, Myles A.; Allebe, Christophe; Geisz, John F.; Paviet-Salomon, Bertrand; Ward, Scott; Descoeudres, Antoine; LaSalvia, Vincenzo; Barraud, Loris; Badel, Nicolas; Faes, Antonin; Levrat, Jacques; Despeisse, Matthieu; Ballif, Christophe; Stradins, Paul; Young, David L.

    2016-07-01

    Combining a Si solar cell with a high-bandgap top cell reduces the thermalization losses in the short wavelength and enables theoretical 1-sun efficiencies far over 30%. We have investigated the fabrication and optimization of Si-based tandem solar cells with 1.8-eV rear-heterojunction GaInP top cells. The III-V and Si heterojunction subcells were fabricated separately and joined by mechanical stacking using electrically insulating optically transparent interlayers. Our GaInP/Si dual-junction solar cells have achieved a certified cumulative 1-sun efficiency of 29.8% +/- 0.6% (AM1.5g) in four-terminal operation conditions, which exceeds the record 1-sun efficiencies achieved with both III-V and Si single-junction solar cells. The effect of luminescent coupling between the subcells has been investigated, and optical losses in the solar cell structure have been addressed.

  3. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    PubMed

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-06

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects.

  4. Observation of Ge bottom cells in InGaP/InGaAs/Ge triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Jung, Haeyong; Jung, Sang Hyun; Kim, Chang Zoo; Jun, Dong Hwan; Kang, Ho Kwan; Kim, Hogyoung

    2014-10-01

    After growing InGaP/InGaAs/Ge triple-junction solar cells, we prepared two different Ge cells by etching down to the GaAs buffer layer (sample A) and the AlGaAs layer (sample B). Then, the photovoltaic properties of these two Ge cells were investigated under various light concentrations in order to find the factors affecting the overall performance of the triple-junction solar cells. Under concentrated light, the open-circuit voltage ( V OC ), fill factor and conversion efficiency were higher for sample A than for sample B. The external quantum efficiency was shown to have a slightly higher value for sample A. Both the tunnel junction layer and the top contact resistance increased the series resistance, which also provided defects acting as leakage path. A comparison to previous works suggests that the conversion efficiency of Ge bottom, if present, is degraded marginally after the growth of the full structure of triple-junction solar cells.

  5. Development of a High Efficiency UVR/IRR Coverglass for Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Russell, John; Jones, Glenn; Hall, James

    2007-01-01

    Cover glasses have been a necessary and integral part of space solar arrays since their inception. The main function of the cover glass is to protect the underlying solar cell from the harsh radiation environment of space. They are formed either from fused silica or specially formulated ceria doped glass types that are resistant to radiation damage, for example Pilkington's CMX, CMG, CMO. Solar cells have steadily increased in performance over the past years, from Silicon cells through textured Silicon cells to GaAs cells and the multijunction cells of today. The optimum coverglass solution for each of these cells has been different. The glass itself has also evolved. In some cases it has had its expansion coefficient matched to the cell substrate material, and in addition, added value has been derived from the application of thin film optical coatings to the coverglass. In the majority of cases this has taken the form of a single layer of MgF2 which acts as an antireflection coating. There are also conductive coatings to address electrostatic discharge issues (ESD) and Ultra Violet Reflective (UVR) and Infrared Reflective (IRR) coatings designed for thermal enhancement. Each type of coating can be applied singly or in combination. This paper describes a new type of UVR/IRR (or blue red reflector BRR) specifically designed for triple junction solar cells. For space applications, where radiation is the principal mechanism for removing heat from the satellite, it is the emittance and solar absorptance that primarily determine the temperature of the array. It is therefore essential that any coatings designed to have an effect on the temperature by reducing the solar absorption have a minimal effect on the overall emittance.

  6. Investigation of room-temperature wafer bonded GaInP/GaAs/InGaAsP triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Yang, Wen-xian; Dai, Pan; Ji, Lian; Tan, Ming; Wu, Yuan-yuan; Uchida, Shiro; Lu, Shu-long; Yang, Hui

    2016-12-01

    We report on the fabrication of III-V compound semiconductor multi-junction solar cells using the room-temperature wafer bonding technique. GaInP/GaAs dual-junction solar cells on GaAs substrate and InGaAsP single junction solar cell on InP substrate were separately grown by all-solid state molecular beam epitaxy (MBE). The two cells were then bonded to a triple-junction solar cell at room-temperature. A conversion efficiency of 30.3% of GaInP/GaAs/InGaAsP wafer-bonded solar cell was obtained at 1-sun condition under the AM1.5G solar simulator. The result suggests that the room-temperature wafer bonding technique and MBE technique have a great potential to improve the performance of multi-junction solar cell.

  7. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    PubMed Central

    Jäckle, Sara; Mattiza, Matthias; Liebhaber, Martin; Brönstrup, Gerald; Rommel, Mathias; Lips, Klaus; Christiansen, Silke

    2015-01-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction. PMID:26278010

  8. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    NASA Astrophysics Data System (ADS)

    Jäckle, Sara; Mattiza, Matthias; Liebhaber, Martin; Brönstrup, Gerald; Rommel, Mathias; Lips, Klaus; Christiansen, Silke

    2015-08-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.

  9. High voltage series connected tandem junction solar battery

    DOEpatents

    Hanak, Joseph J.

    1982-01-01

    A high voltage series connected tandem junction solar battery which comprises a plurality of strips of tandem junction solar cells of hydrogenated amorphous silicon having one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon, arranged in a tandem configuration, can have the same bandgap or differing bandgaps. The tandem junction strip solar cells are series connected to produce a solar battery of any desired voltage.

  10. Theoretical results on the double-collecting tandem junction solar cell. [radiation damage

    NASA Technical Reports Server (NTRS)

    Goradia, C.; Vaughn, J.; Baraona, C. R.

    1980-01-01

    Results of computer calculations using a one dimensional model of the silicon tandem junction solar cell with both front and back current collection are presented. Using realistically achievable geometrical and material parameters, the model predicts that with base widths of 50 micrometers and 100 micrometers and base resistivities between 1 ohm/cm and 20 ohm/cm, beginning of life efficiencies of 14% to 17% and end of life efficiencies of 12% to 14%, after about seven years in synchronous orbit, can be obtained.

  11. Computer modeling of a two-junction, monolithic cascade solar cell

    NASA Technical Reports Server (NTRS)

    Lamorte, M. F.; Abbott, D.

    1979-01-01

    The theory and design criteria for monolithic, two-junction cascade solar cells are described. The departure from the conventional solar cell analytical method and the reasons for using the integral form of the continuity equations are briefly discussed. The results of design optimization are presented. The energy conversion efficiency that is predicted for the optimized structure is greater than 30% at 300 K, AMO and one sun. The analytical method predicts device performance characteristics as a function of temperature. The range is restricted to 300 to 600 K. While the analysis is capable of determining most of the physical processes occurring in each of the individual layers, only the more significant device performance characteristics are presented.

  12. Heavily doped transparent-emitter regions in junction solar cells, diodes, and transistors

    NASA Technical Reports Server (NTRS)

    Shibib, M. A.; Lindholm, F. A.; Therez, F.

    1979-01-01

    The paper presents an analytical treatment of transparent-emitter devices, particularly solar cells, that is more complete than previously available treatments. The proposed approach includes the effects of bandgap narrowing, Fermi-Dirac statistics, built-in field due to impurity profile, and a finite surface recombination velocity at the emitter surface. It is demonstrated that the transparent-emitter model can predict experimental values of Voc observed on n(plus)-p thin diffused junction silicon solar cells made on low-resistivity (0.1 ohm-cm) substrates. A test is included for the self-consistent validity of the transparent-emitter model. This test compares the calculated transit time of minority carriers across the emitter with the Auger-impact minority-carrier lifetime within the emitter region.

  13. Laser annealing of ion implanted CZ silicon for solar cell junction formation

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.

    1981-01-01

    The merits of large spot size pulsed laser annealing of phosphorus implanted, Czochralski grown silicon for function formation of solar cells are evaluated. The feasibility and requirements are also determined to scale-up a laser system to anneal 7.62 cm diameter wafers at a rate of one wafer/second. Results show that laser annealing yields active, defect-free, shallow junction devices. Functional cells with AM 1 conversion efficiencies up to 15.4% for 2 x 2 cm and 2 x 4 cm sizes were attained. For larger cells, 7.62 cm dia., conversion efficiencies ranged up to 14.5%. Experiments showed that texture etched surfaces are not compatible with pulsed laser annealing due to the surface melting caused by the laser energy. When compared with furnace annealed cells, the laser annealed cells generally exhibited conversion efficiencies which were equal to or better than those furnace annealed. In addition, laser annealing has greater throughput potential.

  14. Hole-conductor-free perovskite organic lead iodide heterojunction thin-film solar cells: High efficiency and junction property

    NASA Astrophysics Data System (ADS)

    Shi, Jiangjian; Dong, Juan; Lv, Songtao; Xu, Yuzhuan; Zhu, Lifeng; Xiao, Junyan; Xu, Xin; Wu, Huijue; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2014-02-01

    Efficient hole-conductor-free organic lead iodide thin film solar cells have been fabricated with a sequential deposition method, and a highest efficiency of 10.49% has been achieved. Meanwhile, the ideal current-voltage model for a single heterojunction solar cell is applied to clarify the junction property of the cell. The model confirms that the TiO2/CH3NH3PbI3/Au cell is a typical heterojunction cell and the intrinsic parameters of the cell are comparable to that of the high-efficiency thin-film solar cells.

  15. Method for forming p-n junctions and solar-cells by laser-beam processing

    DOEpatents

    Narayan, Jagdish; Young, Rosa T.

    1979-01-01

    This invention is an improved method for preparing p-n junction devices, such as diodes and solar cells. High-quality junctions are prepared by effecting laser-diffusion of a selected dopant into silicon by means of laser pulses having a wavelength of from about 0.3 to 1.1 .mu.m, an energy area density of from about 1.0 to 2.0 J/cm.sup.2, and a duration of from about 20 to 60 nanoseconds. Initially, the dopant is deposited on the silicon as a superficial layer, preferably one having a thickness in the range of from about 50 to 100 A. Depending on the application, the values for the above-mentioned pulse parameters are selected to produce melting of the silicon to depths in the range from about 1000 A to 1 .mu.m. The invention has been used to produce solar cells having a one-sun conversion efficiency of 10.6%, these cells having no antireflective coating or back-surface fields.

  16. Hybrid photovoltaic junctions: metal/molecular organic insulator/semiconductor MOIS solar cells

    NASA Astrophysics Data System (ADS)

    Har-Lavan, Rotem; Ron, Izhar; Thieblemont, Florent; Cahen, David

    2008-04-01

    Using a dense organic monolayer, self-assembled and directly bound to n-Si, as high quality insulator with a thickness that can be varied from 1.5-2.5 nm, we construct a Metal-Organic Insulator-Semiconductor (MOIS) structure, which, if fabricated with semi-transparent top electrode, performs as a hybrid organic-inorganic photovoltaic device. The feasibility of the concept and the electrical properties of the insulating layer were first shown with a Hg top electrode, allowing use of prior know-how from electron transport through molecular monolayers, but with photon collection only from around the electrode. We then used another bottom-up fabrication technique, in addition to molecular self-assembly, electro-less metal deposition, to implement an all-covalently bound solid state device. Electro-less Au deposition yields an electrically continuous, porous and semi-transparent top electrode, improving photon harvesting. Aside from being a nearly ideal insulator, the monolayer acts to passivate and protect the interfacial Si layer from defects and to decrease the surface state density. In addition the cell, like any MIS solar cell, benefits from that the light needs only to cross a few thin transparent layers (anti-reflective coating, organic insulator) to reach the photovoltaically active cell part. This helps to generate carriers close to the junction area, even by short wavelength photons, and, thus, to increase light collection, compared to p-n junction solar cells. Due to low temperature cell fabrication without high vacuum steps, the MOIS approach might be interesting for low cost solar cells.

  17. Gap/silicon Tandem Solar Cell with Extended Temperature Range

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A. (Inventor)

    2006-01-01

    A two-junction solar cell has a bottom solar cell junction of crystalline silicon, and a top solar cell junction of gallium phosphide. A three (or more) junction solar cell has bottom solar cell junctions of silicon, and a top solar cell junction of gallium phosphide. The resulting solar cells exhibit improved extended temperature operation.

  18. High-Efficiency Silicon/Organic Heterojunction Solar Cells with Improved Junction Quality and Interface Passivation.

    PubMed

    He, Jian; Gao, Pingqi; Ling, Zhaoheng; Ding, Li; Yang, Zhenhai; Ye, Jichun; Cui, Yi

    2016-12-27

    Silicon/organic heterojunction solar cells (HSCs) based on conjugated polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and n-type silicon (n-Si) have attracted wide attention due to their potential advantages of high efficiency and low cost. However, the state-of-the-art efficiencies are still far from satisfactory due to the inferior junction quality. Here, facile treatments were applied by pretreating the n-Si wafer in tetramethylammonium hydroxide (TMAH) solution and using a capping copper iodide (CuI) layer on the PEDOT:PSS layer to achieve a high-quality Schottky junction. Detailed photoelectric characteristics indicated that the surface recombination was greatly suppressed after TMAH pretreatment, which increased the thickness of the interfacial oxide layer. Furthermore, the CuI capping layer induced a strong inversion layer near the n-Si surface, resulting in an excellent field effect passivation. With the collaborative improvements in the interface chemical and electrical passivation, a competitive open-circuit voltage of 0.656 V and a high fill factor of 78.1% were achieved, leading to a stable efficiency of over 14.3% for the planar n-Si/PEDOT:PSS HSCs. Our findings suggest promising strategies to further exploit the full voltage as well as efficiency potentials for Si/organic solar cells.

  19. Progress in GaAs/CuInSe2 tandem junction solar cells

    NASA Technical Reports Server (NTRS)

    Kim, N. P.; Burgess, R. M.; Mickelsen, R. A.; Stanbery, B. J.; Mcclelland, R. W.; King, B. D.; Gale, R. P.

    1991-01-01

    Much more power is required for spacecraft of the future than current vehicles. To meet this increased demand for power while simultaneously meeting other requirements for launch, deployment, and maneuverability, the development of higher-efficiency, lighter-weight, and more radiation resistant photovoltaic cells is essential. Mechanically stacked tandem junction solar cells based on (AlGaAs)GaAs thin film CLEFT (Cleavage of Lateral Epitaxial Film for Transfer) top cells and CuInSe2(CIS) thin film bottom cells are being developed to meet these power needs. The mechanically stacked tandem configuration is chosen due to its interconnect flexibility allowing more efficient array level performance. It also eliminates cell fabrication processing constraints associated with monolithically integrated multi-junction approaches, thus producing higher cell fabrication yields. The GaAs cell is used as the top cell due to its demonstrated high efficiency, and good radiation resistance. Furthermore, it offers a future potential for bandgap tuning using AlGaAs as the absorber to maximize cell performance. The CuInSe2 cell is used as the bottom cell due to superb radiation resistance, stability, and optimal bandgap value in combination with an AlGaAs top cell. Since both cells are incorporated as thin films, this approach provides a potential for very high specific power. This high specific power (W/kg), combined with high power density (W/sq m) resulting from the high efficiency of this approach, makes these cells ideally suited for various space applications.

  20. Axially connected nanowire core-shell p-n junctions: a composite structure for high-efficiency solar cells.

    PubMed

    Wang, Sijia; Yan, Xin; Zhang, Xia; Li, Junshuai; Ren, Xiaomin

    2015-01-01

    A composite nanostructure for high-efficiency solar cells that axially connects nanowire core-shell p-n junctions is proposed. By axially connecting the p-n junctions in one nanowire, the solar spectrum is separated and absorbed in the top and bottom cells with respect to the wavelength. The unique structure of nanowire p-n junctions enables substantial light absorption along the nanowire and efficient radial carrier separation and collection. A coupled three-dimensional optoelectronic simulation is used to evaluate the performance of the structure. With an excellent current matching, a promising efficiency of 19.9% can be achieved at a low filling ratio of 0.283 (the density of the nanowire array), which is much higher than the tandem axial p-n junctions.

  1. Computer analysis of a-Si:H based double junction solar cells

    SciTech Connect

    Palit, N.; Chatterjee, P.

    1997-07-01

    An integrated electrical-optical model has been used to simulate and examine ways of optimizing the performance of double junction solar cells, where both the component cells have a-Si:H absorber layers of identical material quality. In the optical modeling part they take into account both specular interference effects; and diffused reflectances and transmittances due to interface roughness. The model simulates carrier transport in the junction between the two p-i-n subcells with the help of a thin heavily defective recombination layer (RL) having a reduced band gap. Their results reveal that in order to simulate the current-voltage and the quantum efficiency (QE) characteristics of these cells, window losses and light-trapping effects need to be properly accounted for. Results indicate that the highest open-circuit voltage is attained when the majority carrier quasi-Fermi levels on either side of the RL coincide. Also for the highest multijunction cell efficiency the thicknesses of the component subcells are such that the electric field in both are fairly close to one another. Finally, the QE under AM1.5 bias light at the maximum power point has been shown to be extremely sensitive to thickness variations of the component subcells and hence an useful tool for multijunction cell optimization.

  2. Effect of Front-Side Silver Metallization on Underlying n+-p Junction in Multicrystalline Silicon Solar Cells: Preprint

    SciTech Connect

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-06-01

    We report on the effect of front-side Ag metallization on the underlying n+-p junction of multicrystalline Si solar cells. The junction quality beneath the contacts was investigated by characterizing the uniformities of the electrostatic potential and doping concentration across the junction, using scanning Kelvin probe force microscopy and scanning capacitance microscopy. We investigated cells with a commercial Ag paste (DuPont PV159) and fired at furnace setting temperatures of 800 degrees, 840 degrees, and 930 degrees C, which results in actual cell temperatures ~100 degrees C lower than the setting temperature and the three cells being under-, optimal-, and over-fired. We found that the uniformity of the junction beneath the Ag contact was significantly degraded by the over-firing, whereas the junction retained good uniformity with the optimal- and under-fire temperatures. Further, Ag crystallites with widely distributed sizes from <100 nm to several μm were found at the Ag/Si interface of the over-fired cell. Large crystallites were imaged as protrusions into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of the junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent recrystallization with incorporation of impurities in the Ag paste and with formation of crystallographic defects during quenching.

  3. Inverted GaInP/(In)GaAs/InGaAs Triple-Junction Solar Cells with Low-Stress Metamorphic Bottom Junctions: Preprint

    SciTech Connect

    Geisz, J. F.; Kurtz, S. R.; Wanlass, M. W.; Ward, J. S.; Duda, A.; Friedman, D. J.; Olson, J. M.; McMahon, W. E.; Moriarty, T. E.; Kiehl, J. T.; Romero, M. J.; Norman, A. G.; Jones, K. M.

    2008-05-01

    We demonstrate high efficiency performance in two ultra-thin, Ge-free III-V semiconductor triple-junction solar cell device designs grown in an inverted configuration. Low-stress metamorphic junctions were engineered to achieve excellent photovoltaic performance with less than 3 x 106 cm-2 threading dislocations. The first design with band gaps of 1.83/1.40/1.00 eV, containing a single metamorphic junction, achieved 33.8% and 39.2% efficiencies under the standard one-sun global spectrum and concentrated direct spectrum at 131 suns, respectively. The second design with band gaps of 1.83/1.34/0.89 eV, containing two metamorphic junctions achieved 33.2% and 40.1% efficiencies under the standard one-sun global spectrum and concentrated direct spectrum at 143 suns, respectively.

  4. "Direct" measurement of sheet resistance in inter-subcell layers of multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Rumyantsev, Valery D.; Larionov, Valery R.; Pokrovskiy, Pavel V.

    2015-09-01

    The multi-junction cells are sensitive to chromatic aberrations inherent to the lens-type concentrators. At spectrally and spatially inhomogeneous distribution of incident light, considerable lateral currents flow along the inter-subcell layers causing a voltage drop across corresponding sheet resistance and, consequently, a decrease in the cell conversion efficiency. The sheet resistance unit is Ohm-per-square that corresponds to the resistance between two bar-type electrodes on the opposite sides of a thin conductive square. A method of "direct" measurement of this parameter is proposed using lasers for local illumination of the strip-in-shape parts of a rectangular-in-form tested cell. These illuminated parts play a role of electrodes for a lateral current induced by photoexitation. Wavelengths of the lasers have to be chosen to generate photocurrents independently in the neighboring subcells, as well as locally in the upper and lower ones. SPICE model of the method is analyzed and experimental results on the InGaP/InGaAs/Ge triple-junction solar cells are presented.

  5. Detailed physics based modeling of triple-junction InGaP/GaAs/Ge solar cell

    NASA Astrophysics Data System (ADS)

    Fedoseyev, Alexandre; Bald, Timothy; Raman, Ashok; Hubbard, Seth; Forbes, David; Freundlich, Alexandre

    2014-03-01

    Space exploration missions and space electronic equipment require improvements in solar cell efficiency and radiation hardness. Triple-junction photovoltaic (TJ PV) cell is one of the most widely used PV for space missions due to it high efficiency. A proper models and simulation techniques are needed to speed-up the development on novel solar cell devices and reduce the related expenses. In this paper we have developed a detailed 3D TCAD model of a TJ PV cell, and calibrated the various (not accurately known) physical parameters to match experimental data, such as dark and light JV, external quantum efficiency (EQE) . A detailed model of triple-junction InGaP/GaAs/Ge solar cell has been developed and implemented in CFDRC's 3D NanoTCAD simulator. The model schematic, materials, layer thicknesses, doping levels and meshing are discussed. This triple-junction model is based on the experimental measurements of a Spectrolab triple-junction cell by [1] with material layer thicknesses provided by Rochester Institute of Technology [2]. This model of the triple-junction solar cell is primarily intended to simulate the external quantum efficiency, JV and other characteristics of a physical cell. Simulation results of light JV characteristics and EQE are presented. The calculated performance parameters compare well against measured experimental data [1]. Photovoltaic performance parameters (Jsc, Voc, Jm, Vm, FF, and Efficiency) can also be simulated using the presented model. This TCAD model is to be used to design an enhanced TJ PV with increased efficiency and radiation tolerance. Keywords: photovoltaic cell, triple-junction, numerical modeling, TCAD, dark and light JV.

  6. AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack

    NASA Technical Reports Server (NTRS)

    Dinetta, L. C.; Hannon, M. H.; Mcneely, J. B.; Barnett, A. M.

    1991-01-01

    The AstroPower self-supporting, transparent AlGaAs top solar cell can be stacked upon any well-developed bottom solar cell for improved system performance. This is an approach to improve the performance and scale of space photovoltaic power systems. Mechanically stacked tandem solar cell concentrator systems based on the AlGaAs top concentrator solar cell can provide near term efficiencies of 36 percent (AMO, 100x). Possible tandem stack efficiencies greater than 38 percent (100x, AMO) are feasible with a careful selection of materials. In a three solar cell stack, system efficiencies exceed 41 percent (100x, AMO). These device results demonstrate a practical solution for a state-of-the-art top solar cell for attachment to an existing, well-developed solar cell.

  7. Comparison of Theoretical Efficiencies of Multi-junction Concentrator Solar Cells

    SciTech Connect

    Kurtz, S.; Myers, D.; McMahon, W. E.; Geisz, J.; Steiner, M.

    2008-01-01

    Champion concentrator cell efficiencies have surpassed 40% and now many are asking whether the efficiencies will surpass 50%. Theoretical efficiencies of >60% are described for many approaches, but there is often confusion about the theoretical efficiency for a specific structure. The detailed balance approach to calculating theoretical efficiency gives an upper bound that can be independent of material parameters and device design. Other models predict efficiencies that are closer to those that have been achieved. Changing reference spectra and the choice of concentration further complicate comparison of theoretical efficiencies. This paper provides a side-by-side comparison of theoretical efficiencies of multi-junction solar cells calculated with the detailed balance approach and a common one-dimensional-transport model for different spectral and irradiance conditions. Also, historical experimental champion efficiencies are compared with the theoretical efficiencies.

  8. Characterizing the effects of silver alloying in chalcopyrite CIGS solar cells with junction capacitance methods

    SciTech Connect

    Erslev, Peter T.; Hanket, Gregory M.; Shafarman, William N.; Cohen, J. David

    2009-04-01

    A variety of junction capacitance-based characterization methods were used to investigate alloys of Ag into Cu(In1-xGax)Se2 photovoltaic solar cells over a broad range of compositions. These alloys show encouraging trends of increasing VOC with increasing Ag content, opening the possibility of wide-gap cells for use in tandem device applications. Drive level capacitance profiling (DLCP) has shown very low free carrier concentrations for all Ag-alloyed devices, in some cases less than 1014 cm-3, which is roughly an order of magnitude lower than that of CIGS devices. Transient photocapacitance spectroscopy has revealed very steep Urbach edges, with energies between 10 meV and 20 meV, in the Ag-alloyed samples. This is in general lower than the Urbach edges measured for standard CIGS samples and suggests a significantly lower degree of structural disorder.

  9. Highly Monodispersed PbS Quantum Dots for Outstanding Cascaded-Junction Solar Cells

    PubMed Central

    2016-01-01

    High-performance cascaded-junction quantum dot solar cells (CJQDSCs) are fabricated from as-prepared highly monodispersed lead sulfide QDs. The cells have a high power conversion of 9.05% and a short-circuit current density of 32.51 mA cm–2. A reliable and effective stratagem for fabricating high-quality lead sulfide quantum dots (QD) is explored through a “monomer” concentration-controlled experiment. Robust QDSC performances with different band gaps are demonstrated from the as-proposed synthesis and processing stratagems. Various potential CJQDSCs can be envisioned from the band edge evolution of the QDs as a function of size and ligands reported here. PMID:28035335

  10. Fundamental limitations imposed by high doping on the performance of pn junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Li, S. S.; Sah, C. T.

    1975-01-01

    Fundamental limitations imposed on the performance of silicon junction solar cells by physical mechanisms accompanying high doping are described. The one-dimensional mechanisms divide into two broad categories: those associated with band-gap shrinkage and those associated with interband transition rates. By extending the traditional method of analysis and comparing with measurement, it is shown that the latter kind of mechanism dominates in determining the open-circuit voltage in a one-dimensional model of a 0.1 ohm-cm cell at 300 K. As an alternative dominant mechanism, a three-dimensional model involving thermodynamically stable clusters of impurities in the highly-doped diffused layer is suggested.

  11. Can plasmonic Al nanoparticles improve absorption in triple junction solar cells?

    PubMed

    Yang, L; Pillai, S; Green, M A

    2015-07-03

    Plasmonic nanoparticles located on the illuminated surface of a solar cell can perform the function of an antireflection layer, as well as a scattering layer, facilitating light-trapping. Al nanoparticles have recently been proposed to aid photocurrent enhancements in GaAs photodiodes in the wavelength region of 400-900 nm by mitigating any parasitic absorption losses. Because this spectral region corresponds to the top and middle sub-cell of a typical GaInP/GaInAs/Ge triple junction solar cell, in this work, we investigated the potential of similar periodic Al nanoparticles placed on top of a thin SiO2 spacer layer that can also serve as an antireflection coating at larger thicknesses. The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies. Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings. However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells.

  12. Can plasmonic Al nanoparticles improve absorption in triple junction solar cells?

    PubMed Central

    Yang, L.; Pillai, S.; Green, M. A.

    2015-01-01

    Plasmonic nanoparticles located on the illuminated surface of a solar cell can perform the function of an antireflection layer, as well as a scattering layer, facilitating light-trapping. Al nanoparticles have recently been proposed to aid photocurrent enhancements in GaAs photodiodes in the wavelength region of 400–900 nm by mitigating any parasitic absorption losses. Because this spectral region corresponds to the top and middle sub-cell of a typical GaInP/GaInAs/Ge triple junction solar cell, in this work, we investigated the potential of similar periodic Al nanoparticles placed on top of a thin SiO2 spacer layer that can also serve as an antireflection coating at larger thicknesses. The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies. Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings. However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells. PMID:26138405

  13. Multi-junction, monolithic solar cell using low-band-gap materials lattice matched to GaAs or Ge

    DOEpatents

    Olson, Jerry M.; Kurtz, Sarah R.; Friedman, Daniel J.

    2001-01-01

    A multi-junction, monolithic, photovoltaic solar cell device is provided for converting solar radiation to photocurrent and photovoltage with improved efficiency. The solar cell device comprises a plurality of semiconductor cells, i.e., active p/n junctions, connected in tandem and deposited on a substrate fabricated from GaAs or Ge. To increase efficiency, each semiconductor cell is fabricated from a crystalline material with a lattice constant substantially equivalent to the lattice constant of the substrate material. Additionally, the semiconductor cells are selected with appropriate band gaps to efficiently create photovoltage from a larger portion of the solar spectrum. In this regard, one semiconductor cell in each embodiment of the solar cell device has a band gap between that of Ge and GaAs. To achieve desired band gaps and lattice constants, the semiconductor cells may be fabricated from a number of materials including Ge, GaInP, GaAs, GaInAsP, GaInAsN, GaAsGe, BGaInAs, (GaAs)Ge, CuInSSe, CuAsSSe, and GaInAsNP. To further increase efficiency, the thickness of each semiconductor cell is controlled to match the photocurrent generated in each cell. To facilitate photocurrent flow, a plurality of tunnel junctions of low-resistivity material are included between each adjacent semiconductor cell. The conductivity or direction of photocurrent in the solar cell device may be selected by controlling the specific p-type or n-type characteristics for each active junction.

  14. An induced junction photovoltaic cell

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1974-01-01

    Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

  15. Equivalent electron fluence for solar proton damage in GaAs shallow junction cells

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Stock, L. V.

    1984-01-01

    The short-circuit current reduction in GaAs shallow junction heteroface solar cells was calculated according to a simplified solar cell damage model in which the nonuniformity of the damage as a function of penetration depth is treated explicitly. Although the equivalent electron fluence was not uniquely defined for low-energy monoenergetic proton exposure, an equivalent electron fluence is found for proton spectra characteristic of the space environment. The equivalent electron fluence ratio was calculated for a typical large solar flare event for which the proton spectrum is PHI(sub p)(E) = A/E(p/sq. cm) where E is in MeV. The equivalent fluence ratio is a function of the cover glass shield thickness or the corresponding cutoff energy E(sub c). In terms of the cutoff energy, the equivalent 1 MeV electron fluence ratio is r(sub p)(E sub c) = 10(9)/E(sub c)(1.8) where E(sub c) is in units of KeV.

  16. Status of diffused junction p+n InP solar cells for space applications

    NASA Technical Reports Server (NTRS)

    Faur, Mircea; Goradia, C.; Faur, Maria; Fatemi, N. S.; Jenkins, P. P.; Flood, D. J.; Brinker, D. J.; Wilt, D. M.; Bailey, S.; Goradia, M.

    1994-01-01

    Recently, we have succeeded in fabricating diffused junction p(sup +)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3 percent. The maximum AMO, 25 C internal losses due to date on bare cells is, however, only 13.2 percent. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(sup +)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: (1) the formation on thin p(sup +) InP:Cd emitter layers, (2) electroplated front contacts, (3) surface passivation and (4) the design of a new native oxide/Al2O3/MgF2 tree layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.

  17. Tandem photovoltaic solar cell with III-V diffused junction booster cell

    SciTech Connect

    Fraas, L.M.; Avery, J.E.; Girard, G.R.

    1992-02-25

    This patent describes a GaAs/GaSb tandem solar cell having improved conversion efficiency. It comprises: a GaAs upper cell having a predetermined bandgap selected for optimal performance of the tandem solar cell; a GaSb booster cell positioned beneath the GaAs upper cell to receive light transmitted through the GaAs upper cell and responsive to such light; and light conditioning means associated with the upper cell and the booster cell for achieving and energy conversion efficiency of at least 31% AMO. This patent also describes the cell as defined in claim 2, wherein the light conditioning means includes a prismatic coverglass for optically eliminating grid line obscuration losses on at least the upper cell and a concentrating lens for focusing solar energy onto an upper surface of the upper cell.

  18. Thermal influence on charge carrier transport in solar cells based on GaAs PN junctions

    SciTech Connect

    Osses-Márquez, Juan; Calderón-Muñoz, Williams R.

    2014-10-21

    The electron and hole one-dimensional transport in a solar cell based on a Gallium Arsenide (GaAs) PN junction and its dependency with electron and lattice temperatures are studied here. Electrons and heat transport are treated on an equal footing, and a cell operating at high temperatures using concentrators is considered. The equations of a two-temperature hydrodynamic model are written in terms of asymptotic expansions for the dependent variables with the electron Reynolds number as a perturbation parameter. The dependency of the electron and hole densities through the junction with the temperature is analyzed solving the steady-state model at low Reynolds numbers. Lattice temperature distribution throughout the device is obtained considering the change of kinetic energy of electrons due to interactions with the lattice and heat absorbed from sunlight. In terms of performance, higher values of power output are obtained with low lattice temperature and hot energy carriers. This modeling contributes to improve the design of heat exchange devices and thermal management strategies in photovoltaic technologies.

  19. Progress in the Development of Metamorphic Multi-Junction III-V Space-Solar Cells at Essential Research Incorporated

    NASA Technical Reports Server (NTRS)

    Sinharoy, Samar; Patton, Martin O.; Valko, Thomas M., Sr.; Weizer, Victor G.

    2002-01-01

    Theoretical calculations have shown that highest efficiency III-V multi-junction solar cells require alloy structures that cannot be grown on a lattice-matched substrate. Ever since the first demonstration of high efficiency metamorphic single junction 1.1 eV and 1.2 eV InGaAs solar cells by Essential Research Incorporated (ERI), interest has grown in the development of multi-junction cells of this type using graded buffer layer technology. ERI is currently developing a dual-junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air-mass zero (AM0), one-sun efficiency of 28%, and 100-sun efficiency of 37.5%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort at ERI involves the development of a 2.1 eV AlGaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple-junction concentrator tandem cell (projected practical AM0 efficiency of 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual-junction cell performance. In case of the triple-junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper.

  20. Theoretical results on the tandem junction solar cell based on its Ebers-Moll transistor model

    NASA Technical Reports Server (NTRS)

    Goradia, C.; Vaughn, J.; Baraona, C. R.

    1980-01-01

    A one-dimensional theoretical model of the tandem junction solar cell (TJC) with base resistivity greater than about 1 ohm-cm and under low level injection has been derived. This model extends a previously published conceptual model which treats the TJC as an npn transistor. The model gives theoretical expressions for each of the Ebers-Moll type currents of the illuminated TJC and allows for the calculation of the spectral response, I(sc), V(oc), FF and eta under variation of one or more of the geometrical and material parameters and 1MeV electron fluence. Results of computer calculations based on this model are presented and discussed. These results indicate that for space applications, both a high beginning of life efficiency, greater than 15% AM0, and a high radiation tolerance can be achieved only with thin (less than 50 microns) TJC's with high base resistivity (greater than 10 ohm-cm).

  1. Bismuth-catalyzed and doped silicon nanowires for one-pump-down fabrication of radial junction solar cells.

    PubMed

    Yu, Linwei; Fortuna, Franck; O'Donnell, Benedict; Jeon, Taewoo; Foldyna, Martin; Picardi, Gennaro; Roca i Cabarrocas, Pere

    2012-08-08

    Silicon nanowires (SiNWs) are becoming a popular choice to develop a new generation of radial junction solar cells. We here explore a bismuth- (Bi-) catalyzed growth and doping of SiNWs, via vapor-liquid-solid (VLS) mode, to fabricate amorphous Si radial n-i-p junction solar cells in a one-pump-down and low-temperature process in a single chamber plasma deposition system. We provide the first evidence that catalyst doping in the SiNW cores, caused by incorporating Bi catalyst atoms as n-type dopant, can be utilized to fabricate radial junction solar cells, with a record open circuit voltage of V(oc) = 0.76 V and an enhanced light trapping effect that boosts the short circuit current to J(sc) = 11.23 mA/cm(2). More importantly, this bi-catalyzed SiNW growth and doping strategy exempts the use of extremely toxic phosphine gas, leading to significant procedure simplification and cost reduction for building radial junction thin film solar cells.

  2. Degradation modeling of InGaP/GaAs/Ge triple-junction solar cells irradiated by protons

    NASA Astrophysics Data System (ADS)

    Maximenko, S. I.; Lumb, M. P.; Messenger, S. R.; Hoheisel, R.; Affouda, C.; Scheiman, D.; Gonzalez, M.; Lorentzen, J.; Jenkins, P. P.; Walters, R. J.

    2014-03-01

    Experimental results on triple-junction solar cells irradiated by 3 MeV proton irradiation to very high damage levels are presented. The minority carrier transport properties were obtained through quantum efficiency and EBIC measurements and an analytical drift-diffusion solver was used in understanding the results for different degradation levels where multiple damage mechanisms are evident.

  3. Nanopillar Photovoltaics: Photon Management and Junction Engineering for Next-Generation Solar Cells

    NASA Astrophysics Data System (ADS)

    Mariani, Giacomo

    transparent electrode. The second design delves into an in-situ InGaP passivation shell to alleviate the deleterious recombination effects caused by surface states. The efficiency improvement is over six-fold, up to 6.63%, compared to unpassivated devices. Lastly, a p-i-n radial junction nanopillar solar cell highlights external quantum efficiencies in great agreement with numerical simulations. In such framework, the dome morphology of the top transparent contact is found to concentrate and intensify the optical field within the nanopillar active volume, resulting into resonance peaks in the quantum yield measurements, at 7.43% efficiency. These findings confirm the potential of 3D nanopillar solar cells as a cost-effective platform with respect to canonical thin-film photovoltaics.

  4. Effect of junction recombination velocity of electrical parameters of a vertical parallel silicon solar cell under frequency modulation

    NASA Astrophysics Data System (ADS)

    Sahin, Gokhan

    2016-12-01

    This study investigates a theoretical study based on the determination of electrical parameters in solar cell junction vertical parallel silicon under polychromatic illumination and frequency modulation. From the excess minority carrier's density in the solar cell, the photocurrent density and the photovoltage are derived. The route of the current voltage density ( I = f(V)) that materializes the behavior of the generator; we have a model on the shunt resistance and the series resistance. The I- V method is used to determine electrical parameters such as resistance and shunt resistance or various junction recombination velocity. From their expressions, we study their pace according to Bode and Nyquist and then extend the study to other electrical parameter. The Bode diagrams of the diffusion capacitance are shown for different junction recombination velocity.

  5. High Fill Factors of Si Solar Cells Achieved by Using an Inverse Connection Between MOS and PN Junctions.

    PubMed

    Wang, Liang-Xing; Zhou, Zhi-Quan; Zhang, Tian-Ning; Chen, Xin; Lu, Ming

    2016-12-01

    Fill factors (FFs) of ~0.87 have been obtained for crystalline Si (c-Si) solar cells based on Ag front contacts after rapid thermal annealing. The usual single PN junction model fails to explain the high FF result. A metal/oxide/semiconductor (MOS) junction at the emitter is found to be inversely connected to the PN one, and when its barrier height/e is close to the open-circuit voltage of the solar cell, very high FF is obtainable. In this work, although the open-circuit voltage (<580 mV) is not high here, the efficiency of c-Si solar cell still reaches the state-of-the-art value (>20 %) due to the high FF achieved.

  6. A comparison of light-harvesting performance of silicon nanocones and nanowires for radial-junction solar cells

    PubMed Central

    Li, Yingfeng; Li, Meicheng; Fu, Pengfei; Li, Ruike; Song, Dandan; Shen, Chao; Zhao, Yan

    2015-01-01

    Silicon nanorod based radial-junction solar cells are competitive alternatives to traditional planar silicon solar cells. In various silicon nanorods, nanocone is always considered to be better than nanowire in light-absorption. Nevertheless, we find that this notion isn’t absolutely correct. Silicon nanocone is indeed significantly superior over nanowire in light-concentration due to its continuous diameters, and thus resonant wavelengths excited. However, the concentrated light can’t be effectively absorbed and converted to photogenerated carriers, since its propagation path in silicon nanocone is shorter than that in nanowire. The results provide critical clues for the design of silicon nanorod based radial-junction solar cells. PMID:26113194

  7. Performance of single-junction and dual-junction InGaP/GaAs solar cells under low concentration ratios

    SciTech Connect

    Khan, Aurangzeb; Yamaguchi, Masafumi; Takamoto, Tatsuya

    2004-10-11

    A study of the performance of single-junction InGaP/GaAs and dual-junction InGaP/GaAs tandem cells under low concentration ratios (up to 15 suns), before and after 1 MeV electron irradiation is presented. Analysis of the tunnel junction parameters under different concentrated light illuminations reveals that the peak current (J{sub P}) and valley current (J{sub V}) densities should be greater than the short-circuit current density (J{sub sc}) for better performance. The tunnel junction behavior against light intensity improved after irradiation. This led to the suggestion that the peak current density (J{sub P}) and valley current density (J{sub V}) of the tunnel junction were enhanced after irradiation or the peak current was shifted to higher concentration. The recovery of the radiation damage under concentrated light illumination conditions suggests that the performance of the InGaP/GaAs tandem solar cell can be enhanced even under low concentration ratios.

  8. Optical losses in multi-junction a-Si:H based solar cells and modules

    NASA Astrophysics Data System (ADS)

    Wiedeman, S.; Morris, J.; Yang, L.

    A comprehensive optical model is described which is applicable to glass/textured CTO/a-Si:H/a-SiGe:H-based multijunction cells and allows the calculation of optical absorption in each layer of the solar cell. The major optical losses which limit the output current density of tandem cells using 1.72-eV/1.50-eV bandgap a-Si:H/a-SiGe:H and an ITO/Ag rear contact to about 20.8 mA/sq cm (sum of both junctions) are identified and discussed. It is shown that improvements in the reflectivity and scattering properties of the rear contact may be expected to result in current densities of 22.3 mA/sq cm in this type of cell using intrinsic layers of limited thickness. The use of low-cost materials, such as soda-lime glass and the aluminum rear contacts typically employed in the manufacture of large-area modules, should reduce the total current density available to 18.5 mA/sq cm.

  9. InP tunnel junction for InGaAs/InP tandem solar cells

    NASA Technical Reports Server (NTRS)

    Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

    1995-01-01

    Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

  10. Self-deposition of Pt nanoparticles on graphene woven fabrics for enhanced hybrid Schottky junctions and photoelectrochemical solar cells.

    PubMed

    Kang, Zhe; Tan, Xinyu; Li, Xiao; Xiao, Ting; Zhang, Li; Lao, Junchao; Li, Xinming; Cheng, Shan; Xie, Dan; Zhu, Hongwei

    2016-01-21

    In this study, we demonstrated a self-deposition method to deposit Pt nanoparticles (NPs) on graphene woven fabrics (GWF) to improve the performance of graphene-on-silicon solar cells. The deposition of Pt NPs increased the work function of GWF and reduced the sheet resistance of GWF, thereby improving the power conversion efficiency (PCE) of graphene-on-silicon solar cells. The PCE (>10%) was further enhanced via solid electrolyte coating of the hybrid Schottky junction in the photoelectrochemical solar cells. These results suggest that the combination of self-deposition of Pt NPs and solid-state electrolyte coating of graphene-on-silicon is a promising way to produce high performance graphene-on-semiconductor solar cells.

  11. Innovative InGaP/InGaAs/Ge Triple Junction Solar Cells for the Future Russian Missions

    NASA Astrophysics Data System (ADS)

    Ficcadenti, M.; Campesato, R.; Casale, M.; Gabetta, G.; Gori, G.; Kagan, M.; Kholev, B. A.; Ivanov, V.

    2014-08-01

    InGaP/InGaAs/Ge triple junction solar cells with a size of 26.5 cm2, thickness of 140± 20 μm and AM0 efficiency class 30% (CTJ30), have been manufactured and qualified following the ESA ECSS E ST20-08 standard [1].These solar cells are going to power the Kvant constellations named Meteor M and Kanopus.The next generation of Russian spacecraft requires more specific power, for this reason new solar cell approaches based on III-V on silicon and ultrathin substrates are under development. The main advantage of these technologies lie in the possibility to strongly decrease the weight and the cost of the III-V solar cells for space applications.

  12. InGaAs axial-junction nanowire-array solar cells

    NASA Astrophysics Data System (ADS)

    Nakai, Eiji; Chen, Muyi; Yoshimura, Masatoshi; Tomioka, Katsuhiro; Fukui, Takashi

    2015-01-01

    Axial p-i-n junction nanowire (NW) solar cells (SCs) with a position-controlled GaAs-based NW array were fabricated by selective-area metal organic vapor phase epitaxy (SA-MOVPE). The measured electron-beam-induced current (EBIC) signals showed the formation of an axial p-i-n junction, which confirms power generation under sunlight illumination. The series resistance of the NW SCs is much higher than that of conventional planar SCs based on Si or other III-V compound semiconductors. The main difficulty concerning the fabrication of these NW SCs is the degradation of series resistance between the GaAs-based NWs and the indium-tin oxide (ITO) deposited as a transparent electrode. The series resistance of the fabricated GaAs-based NW SCs was reduced by introducing a tin doping contact layer between the ITO and the NW array, which is formed by pulse doping. As a result of this improved structure, the fabricated SCs exhibited an open-circuit voltage of 0.544 V, a short-circuit current of 18.2 mA/cm2, and a fill factor of 0.721 for an overall conversion efficiency of 7.14% under AM1.5G illumination. The series resistance of the SCs could be decreased to 0.132 Ω·cm2, which is one order of magnitude lower than that of the SC without a highly doped contact layer. This reduced series resistance indicates that nanostructure SCs with transparent electrodes and multijunction NW SCs with high efficiencies can be fabricated on a commercial basis in the near future.

  13. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    PubMed

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-07

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.

  14. Nanostructured Solar Cells.

    PubMed

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-08-09

    We are glad to announce the Special Issue "Nanostructured Solar Cells", published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  15. Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles.

    PubMed

    Yeh, Li-Ko; Tian, Wei-Cheng; Lai, Kun-Yu; He, Jr-Hau

    2016-12-14

    GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles.

  16. Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles

    PubMed Central

    Yeh, Li-Ko; Tian, Wei-Cheng; Lai, Kun-Yu; He, Jr-Hau

    2016-01-01

    GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles. PMID:27966621

  17. Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles

    NASA Astrophysics Data System (ADS)

    Yeh, Li-Ko; Tian, Wei-Cheng; Lai, Kun-Yu; He-Hau, Jr.

    2016-12-01

    GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles.

  18. Organic/inorganic hybrid pn-junction between copper phthalocyanine and CdSe quantum dot layers as solar cells

    NASA Astrophysics Data System (ADS)

    Saha, Sudip K.; Guchhait, Asim; Pal, Amlan J.

    2012-08-01

    We have introduced an organic/inorganic hybrid pn-junction for solar cell applications. Layers of II-VI quantum dots and a metal-phthalocyanine in sequence have been used as n- and p-type materials, respectively, to form a junction. The film of quantum dots has been formed through a layer-by-layer process by replacing the long-chain ligands of the nanoparticles in each ultrathin layer or a monolayer with short-chain ones so that interparticle distance becomes small leading to a decrease in resistance of the quantum dot layer. With indium tin oxide and Au as electrodes, we have formed an inverted sandwiched structure. These electrodes formed ohmic contacts with the neighboring materials. From the current-voltage characteristics of the hybrid heterostructure, we have inferred formation of a depletion region at the pn-junction that played a key role in charge separation and correspondingly a photocurrent in the external circuit. For comparison, we have also formed and characterized Schottky devices based on components of the pn-junction keeping the electrode combination same. From capacitance-voltage characteristics, we have observed that the depletion region of the hybrid pn-junction was much wider as compared to that in Schottky devices based on components of the junction.

  19. Palladium nanoparticle array-mediated semiconductor bonding that enables high-efficiency multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Mizuno, Hidenori; Makita, Kikuo; Sugaya, Takeyoshi; Oshima, Ryuji; Hozumi, Yasuo; Takato, Hidetaka; Matsubara, Koji

    2016-02-01

    A detailed study on the application of Pd nanoparticle arrays, produced by self-assembled block copolymer templates, in bonding of III-V-based solar cell materials was carried out. The Pd nanoparticle array-mediated bonding (mechanical stacking) of GaAs-based thin-films (cells) was readily performed on the surface of GaAs or InP-based substrates (cells) to form multi-junction device architectures. Using the optimized Pd NP array, a 30.4%-efficiency four-junction two-terminal cell, consisting of an InGaP/GaAs top cell and an InGaAsP/InGaAs bottom cell, was achieved owing to the excellent electrical and optical bonding properties (bonding resistance, 1.81 Ω cm2; optical loss, 2.9%). Together with the verification of the long-term reliability of the Pd nanoparticle array-mediated bonding, our approach would become practically attractive for producing high-efficiency multi-junction solar cells.

  20. Nanostructured Solar Cells

    PubMed Central

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-01-01

    We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  1. Fullerene-based Schottky-junction organic solar cells: a brief review

    NASA Astrophysics Data System (ADS)

    Sutty, Sibi; Williams, Graeme; Aziz, Hany

    2014-01-01

    Recent advances in fullerene-based Schottky organic solar cells (OSCs) are presented, with a focus on the current understanding of device physics. Fullerene-based Schottky OSCs attain high open-circuit voltages due to the n-type Schottky junction formed between fullerene and an adjacent high work function anode. Small concentrations of donor material doped into the fullerene matrix serve as efficient exciton dissociation and hole transport agents that can substantially bolster short-circuit currents and fill factors. As a consequence, fullerene-based Schottky OSCs have been demonstrated to provide some of the highest-performance vacuum-deposited small molecule OSCs, with power conversion efficiencies up to 8.1%. Fullerene-based Schottky OSCs constructed using different donor materials and varying cathode buffer layers, as studied by a number of different research groups, are presented. To elucidate the differences between Schottky OSCs and more traditional bulk-heterojunction OSCs, we discuss the photophysics of fullerenes, the role of the donor material, and charge transport in low donor concentration active layers. Fullerene-based Schottky OSCs possess considerable advantages because they can reach high efficiencies with a simple structure using readily available and cost-effective materials. The impact and applicability of the Schottky device architecture on the field of organic photovoltaics at large are discussed.

  2. InGaAsN/GaAs heterojunction for multi-junction solar cells

    DOEpatents

    Kurtz, Steven R.; Allerman, Andrew A.; Klem, John F.; Jones, Eric D.

    2001-01-01

    An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 070%.

  3. High Efficiency Amorphous and Microcrystalline Silicon Based Double-Junction Solar Cells made with Very-High-Frequency Glow Discharge

    SciTech Connect

    Banerjee, Arindam

    2004-10-20

    We have achieved a total-area initial efficiency of 11.47% (active-area efficiency of 12.33%) on a-Si:H/μc-Si:H double-junction structure, where the intrinsic layer bottom cell was made in 50 minutes. On another device in which the bottom cell was made in 30 min, we achieved initial total-area efficiency of 10.58% (active-efficiency of 11.35%). We have shown that the phenomenon of ambient degradation of both μc-Si:H single-junction and a-Si:H/μc-Si:H double-junction cells can be attributed to impurity diffusion after deposition. Optimization of the plasma parameters led to alleviation of the ambient degradation. Appropriate current matching between the top and bottom component cells has resulted in a stable total-area efficiency of 9.7% (active-area efficiency of 10.42%) on an a-Si:H/μc-Si:H double-junction solar cell in which the deposition time for the μc-Si:H intrinsic layer deposition was of 30 min.

  4. InGaAsP/InGaAs tandem photovoltaic devices for four-junction solar cells

    NASA Astrophysics Data System (ADS)

    Yongming, Zhao; Jianrong, Dong; Kuilong, Li; Yurun, Sun; Xulu, Zeng; Yang, He; Shuzhen, Yu; Hui, Yang

    2015-04-01

    Lattice-matched InGaAs(P) photovoltaic devices were grown on InP substrates by metal-organic chemical vapor deposition. InGaAsP/InGaAs (1.07/0.74 eV) dual-junction (DJ) solar cells were fabricated and characterized by quantum efficiency and I-V measurements. The open circuit voltage, short circuit current density, fill factor, and efficiency of InGaAsP/InGaAs DJ solar cell are 0.977 V, 10.2 mA/cm2, 80.8%, and 8.94%, respectively, under one sun illumination of the AM 1.5D spectrum. For the InGaAsP/InGaAs DJ solar cell, with increasing concentration, the conversion efficiency first increases steadily and reaches 13% around 280 suns, and finally decreases due to the drop in fill factor at higher concentration ratios. These experimental results demonstrate the promising prospect of GaInP/GaAs/InGaAsP/InGaAs four-junction solar cells. Project supported by the National Natural Science Foundation of China (No. 61376065).

  5. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    SciTech Connect

    Pathirane, M. Iheanacho, B.; Lee, C.-H.; Wong, W. S.; Tamang, A.; Knipp, D.; Lujan, R.

    2015-10-05

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  6. Development and fabrication of a solar cell junction processing system. Quarterly progress report No. 3, October 1980

    SciTech Connect

    Shiesling, R.

    1980-10-01

    The basic objectives of the program are the following: (1) to design, develop, construct and deliver a junction processing system which will be capable of producing solar cell junctions by means of ion implantation followed by pulsed electron beam annealing; (2) to include in the system a wafer transport mechanism capable of transferring 4-inch-diameter wafers into and out of the vacuum chamber where the ion implantation and pulsed electron beam annealing processes take place; (3) to integrate, test and demonstrate the system prior to its delivery to JPL along with detailed operating and maintenance manuals; and (4) to estimate component lifetimes and costs, as necessary for the contract, for the performance of comprehensive analyses in accordance with the Solar Array Manufacturing Industry Costing Standards (SAMICS). Under this contract the automated junction formation equipment to be developed involves a new system design incorporating a modified, government-owned, JPL-controlled ion implanter into a spire-developed pulsed electron beam annealer and wafer transport system. When modified, the ion implanter will deliver a 16 mA beam of /sup 31/P/sup +/ ions with a fluence of 2.5 x 10/sup 15/ ions per square centimeter at an energy of 10 keV. The throughput design goal rate for the junction processor is 10/sup 7/ four-inch-diameter wafers per year. Work on the pulsed electron beam subsystem development is described. (WHK)

  7. Properties Of A Qualified Space Solar Sheet With InGaP/GaAs Dual-Junction Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Imaizumi, Mitsuru; Shimazaki, Kazunori; Kobayashi, Yuki; Takahashi, Masato; Nakamura, Kazuyo; Takamoto, Tatsuya; Sata, Shin-ichiro; Ohshima, Takeshi

    2011-10-01

    JAXA's approach to realizing a high specific power solar paddle by utilizing thin-film III-V multi-junction solar cells is introduced. Thin-film cells laminated with thin and transparent sustaining materials have been named a "Space Solar Sheet (SSS)." Development of the first-generation SSS (SSS-1) was completed in 2010. Thin-film InGaP/GaAs dual-junction (TF2J) cells are used as solar cells in the SSS-1. The AM0 efficiency of the TF2J cells is ~25%. Two types of lamination structure for the active side are employed: one uses transparent films with UV coating, and the other has a conventional configuration using a coverglass. The specific power of the SSS-1 is 0.4-0.5 W/g. Characterization and environmental qualification tests have confirmed their space quality and life at more than 5 years in the LEO environment (the film type) and 10 years in the GEO environment (the coverglass type). The SSS-1 is now commercially available. The second- generation SSS (SSS-2) development started in 2010. The major improvement from the SSS-1 to the SSS-2 will be cell efficiency, achieved by adopting an inverted metamorphic InGaP/GaAs/InGaAs triple-junction solar cell: the target efficiency is 32% at BOL. The lamination technology will be also modified for the SSS-2 to improve specific power. The achievement of such a SSS will enable us to realize lightweight solar paddles with specific power of 150 W/kg or greater.

  8. Composite Transparent Electrode of Graphene Nanowalls and Silver Nanowires on Micropyramidal Si for High-Efficiency Schottky Junction Solar Cells.

    PubMed

    Jiao, Tianpeng; Liu, Jian; Wei, Dapeng; Feng, Yanhui; Song, Xuefen; Shi, Haofei; Jia, Shuming; Sun, Wentao; Du, Chunlei

    2015-09-16

    The conventional graphene-silicon Schottky junction solar cell inevitably involves the graphene growth and transfer process, which results in complicated technology, loss of quality of the graphene, extra cost, and environmental unfriendliness. Moreover, the conventional transfer method is not well suited to conformationally coat graphene on a three-dimensional (3D) silicon surface. Thus, worse interfacial conditions are inevitable. In this work, we directly grow graphene nanowalls (GNWs) onto the micropyramidal silicon (MP) by the plasma-enhanced chemical vapor deposition method. By controlling growth time, the cell exhibits optimal pristine photovoltaic performance of 3.8%. Furthermore, we improve the conductivity of the GNW electrode by introducing the silver nanowire (AgNW) network, which could achieve lower sheet resistance. An efficiency of 6.6% has been obtained for the AgNWs-GNWs-MP solar cell without any chemical doping. Meanwhile, the cell exhibits excellent stability exposed to air. Our studies show a promising way to develop simple-technology, low-cost, high-efficiency, and stable Schottky junction solar cells.

  9. Single-Junction Binary-Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency.

    PubMed

    Zhao, Fuwen; Dai, Shuixing; Wu, Yang; Zhang, Qianqian; Wang, Jiayu; Jiang, Li; Ling, Qidan; Wei, Zhixiang; Ma, Wei; You, Wei; Wang, Chunru; Zhan, Xiaowei

    2017-03-10

    A new fluorinated nonfullerene acceptor, ITIC-Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end-capping group 1,1-dicyanomethylene-3-indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push-pull effect between the donor unit indacenodithieno[3,2-b]thiophene and the acceptor unit IC due to electron-withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short-circuit current density (JSC ). On the other hand, incorporation of F would improve intermolecular interactions through CF···S, CF···H, and CF···π noncovalent interactions and enhance electron mobility, which is beneficial to enhancing JSC and fill factor. Indeed, the results show that fluorinated ITIC-Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC-Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC-Th1 electron acceptor and a wide-bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC-Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene-based single-junction binary-blend OSCs. Moreover, the OSCs based on FTAZ:ITIC-Th1 show much better efficiency and better stability than the control devices based on FTAZ:PC71 BM (PCE = 5.22%).

  10. Improved photovoltaic performance of crystalline-Si/organic Schottky junction solar cells using ferroelectric polymers

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Khatri, I.; Ishikawa, R.; Fujimori, A.; Ueno, K.; Manabe, K.; Nishino, H.; Shirai, H.

    2013-10-01

    The effect of inserting an ultrathin layer of ferroelectric (FE) poly(vinylidene fluoride-tetrafluoroethylene) P(VDF-TeFE) at the crystalline (c-)Si/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) interface of a c-Si/PEDOT:PSS Schottky junction solar cell is demonstrated. P(VDF-TeFE) is a highly resistive material that exhibits a large, permanent, internal polarization electric field by poling of molecular dipole among the polymer chains. Because of these properties, performance can be enhanced by adjusting the thickness of the FE layer and subsequent poling process. Inserting a 3-nm-thick FE layer increases the power conversion efficiency η from 10.2% to 11.4% with a short-circuit current density Jsc of 28.85 mA/cm2, an open-circuit voltage Voc of 0.57 V, and a fill factor FF of 0.692. Subsequent poling of the FE layer under a reverse DC bias stress increased η up to 12.3% with a Jsc of 29.7 mA/cm2, a Voc of 0.58 V, and an FF of 0.71. The obtained results confirm that the spontaneous polarization of the FE layers is responsible for the enhancement of η, and that the polarization-based enhancement works if the FE layer is highly crystalline. These findings originate from efficient charge extraction to the electrodes and a suppression of non-radiative recombination at the c-Si/PEDOT:PSS interface.

  11. A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

    NASA Technical Reports Server (NTRS)

    Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

    1980-01-01

    Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

  12. Novel anti-reflection technology for GaAs single-junction solar cells using surface patterning and Au nanoparticles.

    PubMed

    Kim, Youngjo; Lam, Nguyen Dinh; Kim, Kangho; Kim, Sangin; Rotermund, Fabian; Lim, Hanjo; Lee, Jaejin

    2012-07-01

    Single-junction GaAs solar cell structures were grown by low-pressure MOCVD on GaAs (100) substrates. Micro-rod arrays with diameters of 2 microm, 5 microm, and 10 microm were fabricated on the surfaces of the GaAs solar cells via photolithography and wet chemical etching. The patterned surfaces were coated with Au nanoparticles using an Au colloidal solution. Characteristics of the GaAs solar cells with and without the micro-rod arrays and Au nanoparticles were investigated. The short-circuit current density of the GaAs solar cell with 2 microm rod arrays and Au nanoparticles increased up to 34.9% compared to that of the reference cell without micro-rod arrays and Au nanoparticles. The conversion efficiency of the GaAs solar cell that was coated with Au nanoparticles on the patterned surface with micro-rod arrays can be improved from 14.1% to 19.9% under 1 sun AM 1.5G illumination. These results show that micro-rod arrays and Au nanoparticle coating can be applied together in surface patterning to achieve a novel cost-effective anti-reflection technology.

  13. Realizing high-efficiency omnidirectional n-type Si solar cells via the hierarchical architecture concept with radial junctions.

    PubMed

    Wang, Hsin-Ping; Lin, Tzu-Yin; Hsu, Chia-Wei; Tsai, Meng-Lin; Huang, Chih-Hsiung; Wei, Wan-Rou; Huang, Ming-Yi; Chien, Yi-Jiunn; Yang, Po-Chuan; Liu, Chee-Wee; Chou, Li-Jen; He, Jr-Hau

    2013-10-22

    Hierarchical structures combining micropyramids and nanowires with appropriate control of surface carrier recombination represent a class of architectures for radial p-n junction solar cells that synergizes the advantageous features including excellent broad-band, omnidirectional light-harvesting and efficient separation/collection of photoexcited carriers. The heterojunction solar cells fabricated with hierarchical structures exhibit the efficiency of 15.14% using cost-effective as-cut Czochralski n-type Si substrates, which is the highest reported efficiency among all n-type Si nanostructured solar cells. We also demonstrate the omnidirectional solar cell that exhibits the daily generated power enhancement of 44.2% by using hierarchical structures, as compared to conventional micropyramid control cells. The concurrent improvement in optical and electrical properties for realizing high-efficiency omnidirectional solar cells using as-cut Czochralski n-type Si substrates demonstrated here makes a hierarchical architecture concept promising for large-area and cost-effective mass production.

  14. In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions

    NASA Technical Reports Server (NTRS)

    Harris, R.D.; Imaizumi, M.; Walters, R.J.; Lorentzen, J.R.; Messenger, S.R.; Tischler, J.G.; Ohshima, T.; Sato, S.; Sharps, P.R.; Fatemi, N.S.

    2008-01-01

    The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

  15. Characterization of the heavily doped emitter and junction regions of silicon solar cells using an electron beam

    NASA Technical Reports Server (NTRS)

    Luke, K. L.; Cheng, L.-J.

    1986-01-01

    Heavily doped emitter and junction regions of silicon solar cells are investigated by means of the electron-beam-induced-current (EBIC) technique. Although the experimental EBIC data are collected under three-dimensional conditions, it is analytically demonstrated with two numerical examples that the solutions obtained with one-dimensional numerical modeling are adequate. EBIC data for bare and oxide-covered emitter surfaces are compared with theory. The improvement in collection efficiency when an emitter surface is covered with a 100-A SiO2 film varies with beam energy; for a cell with a junction depth of 0.35 microns, the improvement is about 54 percent at 2 keV.

  16. Optimization of 3-junction inverted metamorphic solar cells for high-temperature and high-concentration operation

    NASA Astrophysics Data System (ADS)

    Geisz, John F.; Duda, Anna; France, Ryan M.; Friedman, Daniel J.; Garcia, Ivan; Olavarria, Waldo; Olson, Jerry M.; Steiner, Myles A.; Ward, J. Scott; Young, Michelle

    2012-10-01

    Four different band gap combinations of triple-junction inverted metamorphic solar cells are characterized as a function of temperature and concentration up to 120°C and ˜1000 suns. We demonstrate that the standard 1.82/1.40/1.00 eV combination is an excellent choice for typical operating conditions of 1000 suns and 75°C. Improved metal grids and thermal management in such a cell has achieved 42.6% efficiency at 327 suns and 40.9% at 1093 suns at 25°C.

  17. Single Junction InGaP/GaAs Solar Cells Grown on Si Substrates using SiGe Buffer Layers

    NASA Technical Reports Server (NTRS)

    Ringel, S. A.; Carlin, J. A.; Andre, C. L.; Hudait, M. K.; Gonzalez, M.; Wilt, D. M.; Clark, E. B.; Jenkins, P.; Scheiman, D.; Allerman, A.

    2002-01-01

    Single junction InGaP/GaAs solar cells displaying high efficiency and record high open circuit voltage values have been grown by metalorganic chemical vapor deposition on Ge/graded SiGe/Si substrates. Open circuit voltages as high as 980 mV under AM0 conditions have been verified to result from a single GaAs junction, with no evidence of Ge-related sub-cell photoresponse. Current AM0 efficiencies of close to 16% have been measured for a large number of small area cells, whose performance is limited by non-fundamental current losses due to significant surface reflection resulting from greater than 10% front surface metal coverage and wafer handling during the growth sequence for these prototype cells. It is shown that at the material quality currently achieved for GaAs grown on Ge/SiGe/Si substrates, namely a 10 nanosecond minority carrier lifetime that results from complete elimination of anti-phase domains and maintaining a threading dislocation density of approximately 8 x 10(exp 5) per square centimeter, 19-20% AM0 single junction GaAs cells are imminent. Experiments show that the high performance is not degraded for larger area cells, with identical open circuit voltages and higher short circuit current (due to reduced front metal coverage) values being demonstrated, indicating that large area scaling is possible in the near term. Comparison to a simple model indicates that the voltage output of these GaAs on Si cells follows ideal behavior expected for lattice mismatched devices, demonstrating that unaccounted for defects and issues that have plagued other methods to epitaxially integrate III-V cells with Si are resolved using SiGe buffers and proper GaAs nucleation methods. These early results already show the enormous and realistic potential of the virtual SiGe substrate approach for generating high efficiency, lightweight and strong III-V solar cells.

  18. III-V compound semiconductor multi-junction solar cells fabricated by room-temperature wafer-bonding technique

    NASA Astrophysics Data System (ADS)

    Arimochi, Masayuki; Watanabe, Tomomasa; Yoshida, Hiroshi; Tange, Takashi; Nomachi, Ichiro; Ikeda, Masao; Dai, Pan; He, Wei; Ji, Lian; Lu, Shulong; Yang, Hui; Uchida, Shiro

    2015-05-01

    We have developed III-V compound semiconductor multi-junction solar cells by a room-temperature wafer-bonding technique to avoid the formation of dislocations and voids due to lattice mismatch and thermal damage during a conventional high-temperature wafer-bonding process. First, we separately grew an (Al)GaAs top cell on a GaAs substrate and an InGaAs bottom cell on an InP substrate by metal solid source molecular beam epitaxy. Thereafter, we successfully bonded these sub-cells by the room-temperature wafer-bonding technique and fabricated (Al)GaAs ∥ InGaAs wafer-bonded solar cells. To the best of our knowledge, the obtained GaAs ∥ InGaAs and AlGaAs ∥ InGaAs wafer-bonded solar cells exhibited the lowest electrical and optical losses ever reported. The AlGaAs ∥ InGaAs solar cells reached the maximum efficiency of 27.7% at 120 suns. These results suggest that the room-temperature wafer-bonding technique has high potential for achieving higher conversion efficiencies.

  19. Requirements for a GaAsBi 1 eV sub-cell in a GaAs-based multi-junction solar cell

    NASA Astrophysics Data System (ADS)

    Thomas, T.; Mellor, A.; Hylton, N. P.; Führer, M.; Alonso-Álvarez, D.; Braun, A.; Ekins-Daukes, N. J.; David, J. P. R.; Sweeney, S. J.

    2015-09-01

    Multi-junction solar cells achieve high efficiency by stacking sub-cells of different bandgaps (typically GaInP/GaAs/Ge) resulting in efficiencies in excess of 40%. The efficiency can be improved by introducing a 1 eV absorber into the stack, either replacing Ge in a triple-junction configuration or on top of Ge in a quad-junction configuration. GaAs0.94Bi0.06 yields a direct-gap at 1 eV with only 0.7% strain on GaAs and the feasibility of the material has been demonstrated from GaAsBi photodetector devices. The relatively high absorption coefficient of GaAsBi suggests sufficient current can be generated to match the sub-cell photocurrent from the other sub-cells of a standard multi-junction solar cell. However, minority carrier transport and background doping levels place constraints on both p/n and p-i-n diode configurations. In the possible case of short minority carrier diffusion lengths we recommend the use of a p-i-n diode, and predict the material parameters that are necessary to achieve high efficiencies in a GaInP/GaAs/GaAsBi/Ge quad-junction cell.

  20. Horizontal Silicon Nanowires with Radial p-n Junctions: A Platform for Unconventional Solar Cells.

    PubMed

    Zhang, Xing; Pinion, Christopher W; Christesen, Joseph D; Flynn, Cory J; Celano, Thomas A; Cahoon, James F

    2013-06-20

    The silicon p-n junction is the most successful solar energy technology to date, yet it accounts for a marginal percentage of worldwide energy production. To change the status quo, a disruptive technological breakthrough is needed. In this Perspective, we discuss the potential for complex silicon nanowires to serve as a platform for next-generation photovoltaic devices. We review the synthesis, electrical characteristics, and optical properties of core/shell silicon nanowires that are subwavelength in diameter and contain radial p-n junctions. We highlight the unique features of these nanowires, such as optical antenna effects that concentrate light and intense built-in electric fields that enable ultrafast charge-carrier separation. We advocate a paradigm in which nanowires are arranged in periodic horizontal arrays to form ultrathin devices. Unlike conventional planar silicon, nanowire structures provide the flexibility to incorporate multiple semiconductor, dielectric, and metallic materials in a single system, providing the foundation for a disruptive, unconventional solar energy technology.

  1. Hybrid pn-junction solar cells based on layers of inorganic nanocrystals and organic semiconductors: optimization of layer thickness by considering the width of the depletion region.

    PubMed

    Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

    2014-03-07

    We report the formation and characterization of hybrid pn-junction solar cells based on a layer of copper diffused silver indium disulfide (AgInS2@Cu) nanoparticles and another layer of copper phthalocyanine (CuPc) molecules. With copper diffusion in the nanocrystals, their optical absorption and hence the activity of the hybrid pn-junction solar cells was extended towards the near-IR region. To decrease the particle-to-particle separation for improved carrier transport through the inorganic layer, we replaced the long-chain ligands of copper-diffused nanocrystals in each monolayer with short-ones. Under illumination, the hybrid pn-junctions yielded a higher short-circuit current as compared to the combined contribution of the Schottky junctions based on the components. A wider depletion region at the interface between the two active layers in the pn-junction device as compared to that of the Schottky junctions has been considered to analyze the results. Capacitance-voltage characteristics under a dark condition supported such a hypothesis. We also determined the width of the depletion region in the two layers separately so that a pn-junction could be formed with a tailored thickness of the two materials. Such a "fully-depleted" device resulted in an improved photovoltaic performance, primarily due to lessening of the internal resistance of the hybrid pn-junction solar cells.

  2. Combinatorial solar cell libraries for the investigation of different metal back contacts for TiO2-Cu2O hetero-junction solar cells.

    PubMed

    Rühle, S; Barad, H N; Bouhadana, Y; Keller, D A; Ginsburg, A; Shimanovich, K; Majhi, K; Lovrincic, R; Anderson, A Y; Zaban, A

    2014-04-21

    Here we present a comprehensive investigation of TiO2-Cu2O hetero-junction solar cells with different back contacts (Au, ITO, Cu or Ag). Combinatorial hetero-junction libraries consisting of a linear TiO2 thickness gradient produced by spray pyrolysis and a bell shaped Cu2O profile synthesized by pulsed laser deposition were chosen to investigate the impact of the two metal oxide layer thicknesses. The back contacts were deposited as round patches onto a grid of 13 × 13 points, 169 contacts for each contact material, forming a library containing 4 × 13 × 13 = 676 back contacts. Each back contact represented a solar cell with an individual TiO2 and Cu2O thickness. I-V measurements show that all four materials provide an ohmic contact and that the open circuit voltage of ∼300 mV is rather independent of both layer thicknesses and contact material. The size of the Cu2O crystals drastically decreases with distance from the center of deposition, which leads to a drastic increase of series resistance when the crystal size is <50 nm.

  3. Two-Dimensional Measurement of n+-p Asymmetrical Junctions in Multicrystalline Silicon Solar Cells Using AFM-Based Electrical Techniques with Nanometer Resolution: Preprint

    SciTech Connect

    Jiang, C. S.; Moutinho, H. R.; Li, J. V.; Al-Jassim, M. M.; Heath, J. T.

    2011-07-01

    Lateral inhomogeneities of modern solar cells demand direct electrical imaging with nanometer resolution. We show that atomic force microscopy (AFM)-based electrical techniques provide unique junction characterizations, giving a two-dimensional determination of junction locations. Two AFM-based techniques, scanning capacitance microscopy/spectroscopy (SCM/SCS) and scanning Kelvin probe force microscopy (SKPFM), were significantly improved and applied to the junction characterizations of multicrystalline silicon (mc-Si) cells. The SCS spectra were taken pixel by pixel by precisely controlling the tip positions in the junction area. The spectra reveal distinctive features that depend closely on the position relative to the electrical junction, which allows us to indentify the electrical junction location. In addition, SKPFM directly probes the built-in potential over the junction area modified by the surface band bending, which allows us to deduce the metallurgical junction location by identifying a peak of the electric field. Our results demonstrate resolutions of 10-40 nm, depending on the techniques (SCS or SKPFM). These direct electrical measurements with nanometer resolution and intrinsic two-dimensional capability are well suited for investigating the junction distribution of solar cells with lateral inhomogeneities.

  4. Hierarchial Junction Solar Cells Based on Hyper-Branched Semiconductor Nanocrystals

    DTIC Science & Technology

    2009-06-30

    that copper (I) sulfide and iron disulfide pyrite generated a much broader impact for photovoltaic solar cell applications. First, a simple low...pure phase iron disulfide pyrite nanocrystals with high purity through a surfactant-assisted hydrothermal reaction. These nanocrystals represent new...and iron disulfide pyrite (FeS2) for photovoltaic solar cell application. First, we demonstrated a simple low temperature solution phase synthesis of

  5. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells

    NASA Astrophysics Data System (ADS)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, Junho; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-06-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the

  6. Carrier generation, recombination, trapping, and transport in semiconductors with position-dependent composition. [in junction solar cells

    NASA Technical Reports Server (NTRS)

    Sah, C.-T.; Lindholm, F. A.

    1977-01-01

    The spatial variation of the chemical composition of a semiconductor modifies the ideal one-electron energy band model as well as the Shockley equations for carrier recombination and transport in two important ways. The random component of the spatial variation introduces localized states in the energy gap by perturbing the band states. The nonrandom component gives rise to the position dependences of the conduction and valence band edges or the electron affinity and the energy gap. This paper gives the modifications of the Shockley equations from these two effects as well as an example of the steady-state recombination rate from distributed gap states in junction solar cells

  7. Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

    SciTech Connect

    Yang, Weiquan; Becker, Jacob; Liu, Shi; Kuo, Ying-Shen; Li, Jing-Jing; Zhang, Yong-Hang; Landini, Barbara; Campman, Ken

    2014-05-28

    This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In{sub 0.49}Ga{sub 0.51}P/GaAs/In{sub 0.49}Ga{sub 0.51}P double-heterostructure PN junction with an ultra-thin 300 nm thick GaAs absorber, combined with a 5 μm thick Al{sub 0.52}In{sub 0.48}P layer with a textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF{sub 2}/ZnS anti-reflective coating demonstrated open-circuit voltages (V{sub oc}) up to 1.00 V, short-circuit current densities (J{sub sc}) up to 24.5 mA/cm{sup 2}, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated J{sub sc} and conversion efficiency of these devices are expected to reach 26.6 mA/cm{sup 2} and 20.7%, respectively.

  8. Printing-based assembly of quadruple-junction four-terminal microscale solar cells and their use in high-efficiency modules.

    PubMed

    Sheng, Xing; Bower, Christopher A; Bonafede, Salvatore; Wilson, John W; Fisher, Brent; Meitl, Matthew; Yuen, Homan; Wang, Shuodao; Shen, Ling; Banks, Anthony R; Corcoran, Christopher J; Nuzzo, Ralph G; Burroughs, Scott; Rogers, John A

    2014-06-01

    Expenses associated with shipping, installation, land, regulatory compliance and on-going maintenance and operations of utility-scale photovoltaics can be significantly reduced by increasing the power conversion efficiency of solar modules through improved materials, device designs and strategies for light management. Single-junction cells have performance constraints defined by their Shockley-Queisser limits. Multi-junction cells can achieve higher efficiencies, but epitaxial and current matching requirements between the single junctions in the devices hinder progress. Mechanical stacking of independent multi-junction cells circumvents these disadvantages. Here we present a fabrication approach for the realization of mechanically assembled multi-junction cells using materials and techniques compatible with large-scale manufacturing. The strategy involves printing-based stacking of microscale solar cells, sol-gel processes for interlayers with advanced optical, electrical and thermal properties, together with unusual packaging techniques, electrical matching networks, and compact ultrahigh-concentration optics. We demonstrate quadruple-junction, four-terminal solar cells with measured efficiencies of 43.9% at concentrations exceeding 1,000 suns, and modules with efficiencies of 36.5%.

  9. Printing-based assembly of quadruple-junction four-terminal microscale solar cells and their use in high-efficiency modules

    NASA Astrophysics Data System (ADS)

    Sheng, Xing; Bower, Christopher A.; Bonafede, Salvatore; Wilson, John W.; Fisher, Brent; Meitl, Matthew; Yuen, Homan; Wang, Shuodao; Shen, Ling; Banks, Anthony R.; Corcoran, Christopher J.; Nuzzo, Ralph G.; Burroughs, Scott; Rogers, John A.

    2014-06-01

    Expenses associated with shipping, installation, land, regulatory compliance and on-going maintenance and operations of utility-scale photovoltaics can be significantly reduced by increasing the power conversion efficiency of solar modules through improved materials, device designs and strategies for light management. Single-junction cells have performance constraints defined by their Shockley-Queisser limits. Multi-junction cells can achieve higher efficiencies, but epitaxial and current matching requirements between the single junctions in the devices hinder progress. Mechanical stacking of independent multi-junction cells circumvents these disadvantages. Here we present a fabrication approach for the realization of mechanically assembled multi-junction cells using materials and techniques compatible with large-scale manufacturing. The strategy involves printing-based stacking of microscale solar cells, sol-gel processes for interlayers with advanced optical, electrical and thermal properties, together with unusual packaging techniques, electrical matching networks, and compact ultrahigh-concentration optics. We demonstrate quadruple-junction, four-terminal solar cells with measured efficiencies of 43.9% at concentrations exceeding 1,000 suns, and modules with efficiencies of 36.5%.

  10. Development of high stable-efficiency, triple-junction a-Si alloy solar cells. Annual subcontract report, July 18, 1994--July 17, 1995

    SciTech Connect

    Deng, X.

    1996-02-01

    This report describes work performed by Energy Conversion Devices, Inc. (ECD) under a 3-year, cost-shared amorphous silicon (a-Si) research program to develop advanced technologies and to demonstrate stable 14%-efficient, triple-junction a-Si alloy solar cells. The technologies developed under the program will then be incorporated into ECD`s continuous roll-to-roll deposition process to further enhance ECD`s photovoltaic manufacturing technology. In ECD`s solar cell design, triple-junction a-Si alloy solar cells are deposited onto stainless-steel substrates coated with Ag/ZnO back-reflector layers. This type of cell design enabled ECD to use a continuous roll- to-roll deposition process to manufacture a-Si PV materials in high volume at low cost. Using this cell design, ECD previously achieved 13.7% initial solar cell efficiency using the following features: (1) a triple-junction, two-band-gap, spectrum-splitting solar cell design; (2) a microcrystalline silicon p-layer; (3) a band-gap-profiled a- SiGe alloy as the bottom cell i-layer; (4) a high-performance AgZnO back-reflector; and (5) a high-performance tunnel junction between component cells. ECD also applied the technology into its 2-MW/yr a- Si production line and achieved the manufacturing of 4-ft{sup 2} PV modules with 8% stable efficiency. During this program, ECD is also further advancing its existing PV technology toward the goal of 14% stable solar cells by performing the following four tasks: (1) improving the stability of the intrinsic a-Si alloy materials; (2) improving the quality of low-band-gap a-SiGe alloy; (3) improving p{sup +} window layers, and (4) developing high stable-efficiency triple-junction a-Si alloy solar cells.

  11. Real-Space Microscopic Electrical Imaging of n+-p Junction Beneath Front-Side Ag Contact of Multicrystalline Si Solar Cells

    SciTech Connect

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-04-15

    We investigated the quality of the n+-p diffused junction beneath the front-side Ag contact of multicrystalline Si solar cells by characterizing the uniformities of electrostatic potential and doping concentration across the junction using the atomic force microscopy-based electrical imaging techniques of scanning Kelvin probe force microscopy and scanning capacitance microscopy. We found that Ag screen-printing metallization fired at the over-fire temperature significantly degrades the junction uniformity beneath the Ag contact grid, whereas metallization at the optimal- and under-fire temperatures does not cause degradation. Ag crystallites with widely distributed sizes were found at the Ag-grid/emitter-Si interface of the over-fired cell, which is associated with the junction damage beneath the Ag grid. Large crystallites protrude into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent re-crystallization with incorporation of Ag and other impurities and with formation of crystallographic defects during quenching. The effect of this junction damage on solar cell performance is discussed.

  12. Light weight low cost InGaP/GaAs dual-junction solar cells on 4" epitaxial liftoff (ELO) wafers

    NASA Astrophysics Data System (ADS)

    Tatavarti, Rao; Hillier, G.; Youtsey, C.; McCallum, D.; Martin, G.; Wibowo, A.; Navaratnarajah, R.; Tuminello, F.; Hertkorn, D.; Disabb, M.; Pan, N.

    2009-08-01

    High-efficiency, low-cost InGaP/GaAs dual-junction epitaxial liftoff (ELO) solar cells have been fabricated on full 4" GaAs substrates. These dual-junction solar cells exhibited an efficiency of 28.69% at AM1.5D, one-sun illumination. This is the highest reported efficiency for dual-junction ELO solar cells to date. After application of antireflection coating, the dual-junction ELO cells also exhibited fill factor >85%, open circuit voltage = 2.37 V, and short circuit current density = 13 mA/cm2. An external quantum efficiency >85% was measured for both the GaAs and InGaP sub-cells. An ELO dual-junction solar cell wafer typically weighs less than 1.7 g and has a total semiconductor thickness <5 μm. Reclaim and reuse of the GaAs substrate after the ELO process has been successfully demonstrated.

  13. The importance of surface recombination and energy-bandgap narrowing in p-n-junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fossum, J. G.; Lindholm, F. A.; Shibib, M. A.

    1979-01-01

    Experimental data demonstrating the sensitivity of open-circuit voltage to front-surface conditions are presented for a variety of p-n-junction silicon solar cells. Analytical models accounting for the data are defined and supported by additional experiments. The models and the data imply that a) surface recombination significantly limits the open-circuit voltage (and the short-circuit current) of typical silicon cells, and b) energy-bandgap narrowing is important in the manifestation of these limitations. The models suggest modifications in both the structural design and the fabrication processing of the cells that would result in substantial improvements in cell performance. The benefits of one such modification - the addition of a thin thermal silicon-dioxide layer on the front surface - are indicated experimentally.

  14. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    SciTech Connect

    Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Yu, Linwei E-mail: linwei.yu@polytechnique.edu

    2015-10-19

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs.

  15. Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report

    SciTech Connect

    Deng, X.; Jones, S.J.; Liu, T.; Izu, M.

    1998-04-01

    This report summarizes Energy Conversion Devices, Inc.`s (ECD) research under this program. ECD researchers explored the deposition of a-Si at high rates using very-high-frequency plasma MHz, and compared these VHF i-layers with radio-frequency (RF) plasma-deposited i-layers. ECD conducted comprehensive research to develop a {mu}c-Si p{sup +} layer using VHF deposition process with the objectives of establishing a wider process window for the deposition of high-quality p{sup +} materials and further enhancing their performance of a-Si solar cells by improving its p-layers. ECD optimized the deposition of the intrinsic a-Si layer and the boron-doped {mu}c-Si p{sup +} layer to improve the V{sub oc}. Researchers deposited wide-bandgap a-Si films using high hydrogen dilution; investigated the deposition of the ZnO layer (for use in back-reflector) using a sputter deposition process involving metal Zn targets; and obtained a baseline fabrication for single-junction a-Si n-i-p devices with 10.6% initial efficiency and a baseline fabrication for triple-junction a-Si devices with 11.2% initial efficiency. ECD researchers also optimized the deposition parameters for a-SiGe with high Ge content; designed a novel structure for the p-n tunnel junction (recombination layer) in a multiple-junction solar cell; and demonstrated, in n-i-p solar cells, the improved stability of a-Si:H:F materials when deposited using a new fluorine precursor. Researchers investigated the use of c-Si(n{sup +})/a-Si alloy/Pd Schottky barrier device as a tool for the effective evaluation of photovoltaic performance on a-Si alloy materials. Through alterations in the deposition conditions and system hardware, researchers improved their understanding for the deposition of uniform and high-quality a-Si and a-SiGe films over large areas. ECD researchers also performed extensive research to optimize the deposition process of the newly constructed 5-MW back-reflector deposition machine.

  16. Thermodynamic efficiency limits of classical and bifacial multi-junction tandem solar cells: An analytical approach

    NASA Astrophysics Data System (ADS)

    Alam, Muhammad Ashraful; Khan, M. Ryyan

    2016-10-01

    Bifacial tandem cells promise to reduce three fundamental losses (i.e., above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction photovoltaic (PV) systems. The successive filtering of light through the bandgap cascade and the requirement of current continuity make optimization of tandem cells difficult and accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple analytical approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can be obtained with a few lines of algebra. This powerful approach reproduces, as special cases, all of the known results of conventional and bifacial tandem cells and highlights the asymptotic efficiency gain of these technologies.

  17. Titanium dioxide/zinc indium sulfide hetero-junction: An efficient photoanode for the dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Hou, Wenjing; Xiao, Yaoming; Han, Gaoyi; Zhang, Ying; Chang, Yunzhen

    2016-10-01

    A facile strategy is developed for the fabrication of titanium dioxide/zinc indium sulfide (TiO2/ZnIn2S4) hetero-junction photoanode with an adjustable ZnIn2S4 doping content and application in the dye-sensitized solar cell (DSSC). Comparing to the pure TiO2, TiO2/ZnIn2S4 hetero-junction materials demonstrate an enhanced light utilizing efficiency, a reduced recombination rate of electron-hole pairs, and an accelerated migration process of photoinduced electrons. Due to above merits, DSSC based on TiO2/ZnIn2S4 hetero-junction photoanode achieves a greatly enhanced short-circuit current density, leading to an improved photoelectric conversion efficiency of 8.09% under full sunlight illumination (100 mW cm-2, AM 1.5 G), which is almost 14.43% higher than that of the pure TiO2-based DSSC (7.07%).

  18. An integrated approach to realizing high-performance liquid-junction quantum dot sensitized solar cells

    PubMed Central

    McDaniel, Hunter; Fuke, Nobuhiro; Makarov, Nikolay S.; Pietryga, Jeffrey M.; Klimov, Victor I.

    2013-01-01

    Solution-processed semiconductor quantum dot solar cells offer a path towards both reduced fabrication cost and higher efficiency enabled by novel processes such as hot-electron extraction and carrier multiplication. Here we use a new class of low-cost, low-toxicity CuInSexS2−x quantum dots to demonstrate sensitized solar cells with certified efficiencies exceeding 5%. Among other material and device design improvements studied, use of a methanol-based polysulfide electrolyte results in a particularly dramatic enhancement in photocurrent and reduced series resistance. Despite the high vapour pressure of methanol, the solar cells are stable for months under ambient conditions, which is much longer than any previously reported quantum dot sensitized solar cell. This study demonstrates the large potential of CuInSexS2−x quantum dots as active materials for the realization of low-cost, robust and efficient photovoltaics as well as a platform for investigating various advanced concepts derived from the unique physics of the nanoscale size regime. PMID:24322379

  19. Efficiency enhancement InGaP/GaAs dual-junction solar cell with subwavelength antireflection nanorod arrays.

    PubMed

    Tsai, Min-An; Chen, Hsin Chu; Tseng, Ping Chen; Yu, Peichen; Chiu, Chin Hua; Kuo, Hao Chung; Lin, Shiuan Huei

    2011-12-01

    The enhanced conversion efficiency of the InGaP/GaAs dual-junction solar cell was demonstrated utilizing broad-band and omnidirectional antireflection nanorod arrays. The nanorod arrays were fabricated by self-assembled Ni clusters, followed by inductively-coupled-plasma reactive ion etching. The conversion efficiency measured under one-sun air mass 1.5 global illuminations at room temperature was improved by 10.8%. The light absorption efficiencies of the top InGaP and bottom GaAs cells were also studied under the influence of nanorod arrays. The enhanced absorption efficiency was mostly contributed from the short wavelength absorption by top cell. Surface nanorod arrays served not only as broad-band omnidirectional antireflection layers but also scattering sources. The structure can be further optimized to obtain the maximum conversion efficiency.

  20. High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes.

    PubMed

    Ye, Yu; Dai, Yu; Dai, Lun; Shi, Zujin; Liu, Nan; Wang, Fei; Fu, Lei; Peng, Ruomin; Wen, Xiaonan; Chen, Zhijian; Liu, Zhongfan; Qin, Guogang

    2010-12-01

    High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ∼0.15 V, a short circuit current of ∼275.0 pA, and an energy conversion efficiency of up to ∼1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.

  1. p-n junction improvements of Cu2ZnSnS4/CdS monograin layer solar cells

    NASA Astrophysics Data System (ADS)

    Kauk-Kuusik, M.; Timmo, K.; Danilson, M.; Altosaar, M.; Grossberg, M.; Ernits, K.

    2015-12-01

    In this work we studied the influence of oxidative etching of CZTS monograin surface to the performance of CZTS monograin layer solar cells. The chemistry of CZTS monograin powder surfaces submitted to bromine in methanol and KCN aqueous solutions was investigated by X-ray photoelectron spectroscopy. After bromine etching, elemental sulfur, Sn-O and/or Sn-Br species are formed on the CZTS crystal surface. Sulfur is completely removed by subsequent KCN etching, but oxides and bromides remained on the surface until CdS deposition. These species dissolve in alkaline solution and influence properties of CdS. The conversion efficiency of solar cells improved after the chemical etching prior to CdS deposition and the effect can be attributed to the change of the absorber material crystals surface composition and properties suitable for the effective p-n junction formation. The best CZTS monograin layer solar cell showed conversation efficiency of 7.04% (active area 9.38%).

  2. Engineering of contact resistance between transparent single-walled carbon nanotube films and a-Si:H single junction solar cells by gold nanodots.

    PubMed

    Kim, Jeehwan; Hong, Augustin J; Chandra, Bhupesh; Tulevski, George S; Sadana, Devendra K

    2012-04-10

    The viability of single-walled carbon nanotubes (SWCNTs) as a transparent conducting electrode on a-Si:H based single junction solar cells was explored. A Schottky barrier formed at a SWCNT/a-Si:H interface was removed by introducing high work function gold nanodots at the SWCNT/a-Si:H interface. This allows comparable device performance from SWCNT-electrode-based a-Si:H solar cells to that obtained by using conventional transparent conducting oxides.

  3. Analytical study on the temperature dependence of InGaN p-n junction solar cell under concentrated light intensity

    NASA Astrophysics Data System (ADS)

    Mesrane, A.; Mahrane, A.; Rahmoune, F.; Oulebsir, A.

    2017-02-01

    In this paper, we have theoretically studied the temperature dependence of the InGaN p-n junction solar cell under concentrated irradiance. The electrical parameters of the solar cell were calculated at different temperatures and irradiance concentration. The temperature dependence of the physical parameters is investigated too. The calculated temperature coefficient of the short circuit current density, the open circuit voltage, the maximum output power, the fill factor and the conversion efficiency of the In0.622Ga0.378N solar cell are respectively, +0.00386, -0.188, -0.253, -0. 068 and -0.253%/K. The effect of the temperature and the irradiance concentration on the temperature coefficients of each electrical parameter was also studied. The calculated voltage temperature variation of the In0.622Ga0.378N single junction solar cell was compared with that obtained with other materials single solar cells. The excellent behavior of the In0.622Ga0.378N p-n junction solar cell with temperature and concentrated light intensity allows it to be a promising candidate for operating in hostile environment.

  4. Current-matched, high-efficiency, multi-junction monolithic solar cells

    SciTech Connect

    Olson, J.M.; Kurtz, S.R.

    1991-02-11

    In this invention, the efficiency of a two-junction (cascade) tandem photovoltaic device is improved by adjusting (decreasing) the top cell thickness to achieve current matching. An example of the invention was fabricated out of Ga{sub 0.52}In{sub 0.48}P and GaAs. Additional lattice-matched systems to which the invention pertains include Al{sub x}Ga{sub l-x}/GaAs (x=0.3 {minus} 0.4), GaAs/Ge and Ga{sub y}In{sub 1-y}P/Ga{sub y+0.5}In{sub 0.5-{sub Y}} As (O

  5. InGaP/GaAs/InGaAsP triple junction solar cells grown using solid-source molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Sugaya, T.; Makita, K.; Mizuno, H.; Mochizuki, T.; Oshima, R.; Matsubara, K.; Okano, Y.; Niki, S.

    2015-09-01

    We report mechanically stacked InGaP (1.9 eV)/GaAs (1.42 eV)/InGaAsP (1.0 eV) triple junction solar cells fabricated with an advanced bonding technique using Pd nanoparticle arrays. High quality InGaP/GaAs tandem top and InGaAsP bottom cells are grown on GaAs and InP substrates, respectively using solid-source molecular beam epitaxy (MBE). The InGaAsP bottom cell has an open circuit voltage (Voc) of 0.49 V, which indicates that high performance InGaAsP solar cells can be fabricated using solid-source MBE. A fabricated triple junction solar cell has a high efficiency of 25.6% with a high Voc of 2.66 V.

  6. Towards the Ultimate Multi-Junction Solar Cell using Transfer Printing

    SciTech Connect

    Lumb, Matthew P.; Meitl, Matt; Schmieder, Kenneth J.; Gonzalez, Maria; Mack, Shawn; Yakes, Michael K.; Bennett, Mitchell F.; Frantz, Jesse; Steiner, Myles A.; Geisz, John F.; Friedman, Daniel J.; Slocum, Michael A.; Hubbard, Seth M.; Fisher, Brent; Burroughs, Scott; Walters, Robert J.

    2016-11-21

    Transfer printing is a uniquely enabling technology for the heterogeneous integration of III-V materials grown on dissimilar substrates. In this paper, we present experimental results for a mechanically stacked tandem cell using GaAs and GaSb-based materials capable of harvesting the entire solar spectrum with 44.5% efficiency. We also present the latest results toward developing an ultra-high performance heterogeneous cell, integrating materials grown on GaAs, InP and GaSb platforms.

  7. Towards 12% stabilised efficiency in single junction polymorphous silicon solar cells: experimental developments and model predictions

    NASA Astrophysics Data System (ADS)

    Abolmasov, Sergey; Cabarrocas, Pere Roca i.; Chatterjee, Parsathi

    2016-01-01

    We have combined recent experimental developments in our laboratory with modelling to devise ways of maximising the stabilised efficiency of hydrogenated amorphous silicon (a-Si:H) PIN solar cells. The cells were fabricated using the conventional plasma enhanced chemical vapour deposition (PECVD) technique at various temperatures, pressures and gas flow ratios. A detailed electrical-optical simulator was used to examine the effect of using wide band gap P-and N-doped μc-SiOx:H layers, as well as a MgF2 anti-reflection coating (ARC) on cell performance. We find that with the best quality a-Si:H so far produced in our laboratory and optimised deposition parameters for the corresponding solar cell, we could not attain a 10% stabilised efficiency due to the high stabilised defect density of a-Si:H, although this landmark has been achieved in some laboratories. On the other hand, a close cousin of a-Si:H, hydrogenated polymorphous silicon (pm-Si:H), a nano-structured silicon thin film produced by PECVD under conditions close to powder formation, has been developed in our laboratory. This material has been shown to have a lower initial and stabilised defect density as well as higher hole mobility than a-Si:H. Modelling indicates that it is possible to attain stabilised efficiencies of 12% when pm-Si:H is incorporated in a solar cell, deposited in a NIP configuration to reduce the P/I interface defects and combined with P- and N-doped μc-SiOx:H layers and a MgF2 ARC.

  8. Charge separation in subcells of triple-junction solar cells revealed by time-resolved photoluminescence spectroscopy.

    PubMed

    Tex, David M; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-11-30

    We measure the excitation-wavelength and power dependence of time-resolved photoluminescence (PL) from the top InGaP subcell in a InGaP/GaAs/Ge triple-junction solar cell. The wavelength-dependent data reveals that the PL decays are governed by charge separation. A fast single-exponential PL decay is observed at low excitation power densities, which is the charge separation under short-circuit condition. Under strong excitation a bi-exponential PL decay is observed. Its slow component appears at early times, followed by a faster component at late times. The slow decay is the carrier recombination of the subcell. The following fast component is the charge separation process under reduced built-in potential near the operating point. The subcells electrical conversion efficiency close to the operating point is evaluated using this decay time constant.

  9. Understanding causes and effects of non-uniform light distributions on multi-junction solar cells: Procedures for estimating efficiency losses

    NASA Astrophysics Data System (ADS)

    Herrero, Rebeca; Victoria, Marta; Domínguez, César; Askins, Stephen; Antón, Ignacio; Sala, Gabriel

    2015-09-01

    This paper presents the mechanisms of efficiency losses that have to do with the non-uniformity of the irradiance over the multi-junction solar cells and different measurement techniques used to investigate them. To show the capabilities of the presented techniques, three different concentrators (that consist of an acrylic Fresnel lens, different SOEs and a lattice matched multi-junction cell) are evaluated. By employing these techniques is possible to answer some critical questions when designing concentrators as for example which degree of non-uniformity the cell can withstand, how critical the influence of series resistance is, or what kind of non-uniformity (spatial or spectral) causes more losses.

  10. Finite mobility effects on the radiative efficiency limit of pn -junction solar cells

    NASA Astrophysics Data System (ADS)

    Mattheis, Julian; Werner, Jürgen H.; Rau, Uwe

    2008-02-01

    The maximum power conversion efficiency of a solar cell as defined by the Shockley-Queisser (SQ) radiative recombination limit relies on the assumption that the collection probability for all photogenerated electron/hole pairs is unity. This assumption implies a virtually infinite mobility μn of the photogenerated charge carriers. In order to compute the radiative efficiency limit with finite mobilities, we solve the continuity equation for minority carrier transport including an additional photon recycling term that accounts for emission of photons by radiative recombination and their subsequent reabsorption. This approach quantitatively connects the SQ approach with the classical diode theory. Even when assuming radiative recombination as the only loss mechanism, the maximum efficiency achievable within our model is reduced drastically when μn drops below a critical value. This critical value depends on the absorption coefficient, the doping density of the absorber material, as well as on the thickness and the light trapping scheme of the solar cell. Thus, these material and device parameters gain a fundamental importance as soon as finite carrier mobility is considered. Our theory yields a criterion that has to be fulfilled by any photovoltaic material in order to guarantee charge separation even in an otherwise most ideal case. Exemplary application of our model to three real photovoltaic materials, crystalline silicon (c-Si) , amorphous silicon (a-Si:H) , as well as Cu(In,Ga)Se2 (CIGS), shows that mobilities of c-Si and CIGS are three, respectively, 1 order of magnitude above this critical limit whereas the effective hole mobilities in a-Si:H are scattered around the critical value. A comparison between solar cells and light-emitting diodes with finite mobility and finite nonradiative lifetime reveals that materials for these complementary devices have to fulfill different requirements.

  11. Cu2ZnSnS4 (CZTS) nanoparticle based nontoxic and earth-abundant hybrid pn-junction solar cells.

    PubMed

    Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

    2012-06-14

    A heterojunction between a layer of CZTS nanoparticles and a layer of fullerene derivatives forms a pn-junction. We have used such an inorganic-organic hybrid pn-junction device for solar cell applications. As routes to optimize device performance, interdot separation has been reduced by replacing long-chain ligands of the quantum dots with short-chain ligands and thickness of the CZTS layer has been varied. We have shown that the CZTS-fullerene interface could dissociate photogenerated excitons due to the depletion region formed at the pn-junction. From capacitance-voltage characteristics, we have determined the width of the depletion region, and compared it with the parameters of devices based on the components of the heterojunction. The results demonstrate solar cell applications based on nontoxic and earth-abundant materials.

  12. The role of hydrogenated amorphous silicon oxide buffer layer on improving the performance of hydrogenated amorphous silicon germanium single-junction solar cells

    NASA Astrophysics Data System (ADS)

    Sritharathikhun, Jaran; Inthisang, Sorapong; Krajangsang, Taweewat; Krudtad, Patipan; Jaroensathainchok, Suttinan; Hongsingtong, Aswin; Limmanee, Amornrat; Sriprapha, Kobsak

    2016-12-01

    Hydrogenated amorphous silicon oxide (a-Si1-xOx:H) film was used as a buffer layer at the p-layer (μc-Si1-xOx:H)/i-layer (a-Si1-xGex:H) interface for a narrow band gap hydrogenated amorphous silicon germanium (a-Si1-xGex:H) single-junction solar cell. The a-Si1-xOx:H film was deposited by plasma enhanced chemical vapor deposition (PECVD) at 40 MHz in a same processing chamber as depositing the p-type layer. An optimization of the thickness of the a-Si1-xOx:H buffer layer and the CO2/SiH4 ratio was performed in the fabrication of the a-Si1-xGex:H single junction solar cells. By using the wide band gap a-Si1-xOx:H buffer layer with optimum thickness and CO2/SiH4 ratio, the solar cells showed an improvement in the open-circuit voltage (Voc), fill factor (FF), and short circuit current density (Jsc), compared with the solar cells fabricated using the conventional a-Si:H buffer layer. The experimental results indicated the excellent potential of the wide-gap a-Si1-xOx:H buffer layers for narrow band gap a-Si1-xGex:H single junction solar cells.

  13. Development of 1.25 eV InGaAsN for triple junction solar cells

    SciTech Connect

    LI,N.Y.; SHARPS,P.R.; HILLS,J.S.; HOU,H.; CHANG,PING-CHIH; BACA,ALBERT G.

    2000-05-16

    Development of next generation high efficiency space monolithic multifunction solar cells will involve the development of new materials lattice matched to GaAs. One promising material is 1.05 eV InGaAsN, to be used in a four junction GaInP{sub 2}/GaAs/InGaAsN/Ge device. The AMO theoretical efficiency of such a device is 38--42%. Development of the 1.05 eV InGaAsN material for photovoltaic applications, however, has been difficult. Low electron mobilities and short minority carrier lifetimes have resulted in short minority carrier diffusion lengths. Increasing the nitrogen incorporation decreases the minority carrier lifetime. The authors are looking at a more modest proposal, developing 1.25 eV InGaAsN for a triple junction GaInP{sub 2}/InGaAsN/Ge device. The AMO theoretical efficiency of this device is 30--34%. Less nitrogen and indium are required to lower the bandgap to 1.25 eV and maintain the lattice matching to GaAs. Hence, development and optimization of the 1.25 eV material for photovoltaic devices should be easier than that for the 1.05 eV material.

  14. Direct electrical contact of slanted ITO film on axial p-n junction silicon nanowire solar cells.

    PubMed

    Lee, Ya-Ju; Yao, Yung-Chi; Yang, Chia-Hao

    2013-01-14

    A novel scheme of direct electrical contact on vertically aligned silicon nanowire (SiNW) axial p-n junction is demonstrated by means of oblique-angle deposition of slanted indium-tin-oxide (ITO) film for photovoltaic applications. The slanted ITO film exhibits an acceptable resistivity of 1.07 x 10⁻³Ω-cm underwent RTA treatment of T = 450°C, and the doping concentration and carrier mobility by Hall measurement amount to 3.7 x 10²⁰ cm⁻³ and 15.8 cm²/V-s, respectively, with an n-type doping polarity. Because of the shadowing effect provided by the SiNWs, the incident ITO vapor-flow is deposited preferentially on the top of SiNWs, which coalesces and eventually forms a nearly continuous film for the subsequent fabrication of grid electrode. Under AM 1.5 G normal illumination, our axial p-n junction SiNW solar cell exhibits an open circuit voltage of VOC = 0.56 V, and a short circuit current of JSC = 1.54 mA/cm² with a fill factor of FF = 30%, resulting in a total power conversion efficiency of PEC = 0.26%.

  15. Optical and carrier transport properties of graphene oxide based crystalline-Si/organic Schottky junction solar cells

    NASA Astrophysics Data System (ADS)

    Khatri, I.; Tang, Z.; Hiate, T.; Liu, Q.; Ishikawa, R.; Ueno, K.; Shirai, H.

    2013-12-01

    We investigated the graphene oxide (GO) based n-type crystalline silicon (c-Si)/conductive poly(ethylene dioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) Schottky junction devices with optical characterization and carrier transport measurement techniques. The optical transmittance in the UV region decreased markedly for the films with increasing the concentration of GO whereas it increased markedly in the visible-infrared regions. Spectroscopic ellipsometry revealed that the ordinary and extraordinary index of refraction increased with increasing the concentration of GO. The hole mobility also increased from 1.14 for pristine film to 1.85 cm2/V s for the 12-15 wt. % GO modified film with no significant increases of carrier concentration. The highest conductivity was found for a 15 wt. % GO modified PEDOT:PSS film: the c-Si/PEDOT:PSS:GO device using this sample exhibited a relatively high power conversion efficiency of 11.04%. In addition, the insertion of a 2-3 nm-thick GO thin layer at the c-Si/PEDOT:PSS interface suppressed the carrier recombination efficiency of dark electron and photo-generated hole at the anode, resulting in the increased photovoltaic performance. This study indicates that the GO can be good candidates for hole transporting layer of c-Si/PEDOT:PSS Schottky junction solar cell.

  16. Optical and carrier transport properties of graphene oxide based crystalline-Si/organic Schottky junction solar cells

    SciTech Connect

    Khatri, I.; Tang, Z.; Hiate, T.; Liu, Q.; Ishikawa, R.; Ueno, K.; Shirai, H.

    2013-12-21

    We investigated the graphene oxide (GO) based n-type crystalline silicon (c-Si)/conductive poly(ethylene dioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) Schottky junction devices with optical characterization and carrier transport measurement techniques. The optical transmittance in the UV region decreased markedly for the films with increasing the concentration of GO whereas it increased markedly in the visible-infrared regions. Spectroscopic ellipsometry revealed that the ordinary and extraordinary index of refraction increased with increasing the concentration of GO. The hole mobility also increased from 1.14 for pristine film to 1.85 cm{sup 2}/V s for the 12–15 wt. % GO modified film with no significant increases of carrier concentration. The highest conductivity was found for a 15 wt. % GO modified PEDOT:PSS film: the c-Si/PEDOT:PSS:GO device using this sample exhibited a relatively high power conversion efficiency of 11.04%. In addition, the insertion of a 2–3 nm-thick GO thin layer at the c-Si/PEDOT:PSS interface suppressed the carrier recombination efficiency of dark electron and photo-generated hole at the anode, resulting in the increased photovoltaic performance. This study indicates that the GO can be good candidates for hole transporting layer of c-Si/PEDOT:PSS Schottky junction solar cell.

  17. Design of InP-based metamorphic high-efficiency five-junction solar cells for concentrated photovoltaics

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Yang, Hui

    2015-10-01

    We propose an InP-based upright five-junction (5J) solar cell structure for high conversion efficiency under concentration. In the structure, three bottom subcells are composed of lattice-matched (LM) InGaAsP materials, while two top subcells employ metamorphic InGaP materials. The two InGaP subcells are designed to have the same Ga composition of 30%. The first InGaP subcell is thinned so as to transmit half of the photon flux to the second InGaP subcell, thus forming an upright 5J InGaP(1.64 eV)/InGaP(1.64 eV)/InGaAsP(1.3 eV)/InGaAsP(1.02 eV)/InGaAs(0.74 eV) solar cell structure on the InP substrate. The subcell bandgap energies are chosen in such a way that a current matching condition can be achieved. Because no Al- or N-contained materials are used in the absorbers and only one metamorphic growth is required (with a lattice mismatch of 2.1%), the novel InP-based solar cell architecture is considered practically achievable with current growth technology. By comparing it with a InGaP/GaAs/Ge reference cell and adding additional nonideal factors in the modeling, an efficiency as high as 46.2% is estimated under concentration at ∼1500 suns.

  18. Electrospray Deposition of Poly(3-hexylthiophene) Films for Crystalline Silicon/Organic Hybrid Junction Solar Cells

    NASA Astrophysics Data System (ADS)

    Ino, Tomohisa; Ono, Masahiro; Miyauchi, Naoto; Liu, Qiming; Tang, Zeguo; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime

    2012-06-01

    The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) films for use in crystalline silicon/organic hybrid heterojunction solar cells on a crystalline silicon (c-Si) wafer was investigated using real-time characterization by spectroscopic ellipsometry (SE). In contrast to the nonuniform deposition of products frequently obtained by spin-coating, a uniform deposition of P3HT films was achieved on flat and textured hydrophobic c-Si wafers by adjusting the deposition conditions. Similar findings were also obtained for the deposition of conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on P3HT. The c-Si/P3HT/PEDOT:PSS heterojunction solar cells exhibited efficiencies of 4.1 and 6.3% on flat and textured c-Si wafers, respectively. These findings suggest that ESD is a promising method for the uniform deposition of P3HT and PEDOT:PSS films on flat and textured hydrophobic substrates.

  19. Systematic investigation of benzodithiophene- and diketopyrrolopyrrole-based low-bandgap polymers designed for single junction and tandem polymer solar cells.

    PubMed

    Dou, Letian; Gao, Jing; Richard, Eric; You, Jingbi; Chen, Chun-Chao; Cha, Kitty C; He, Youjun; Li, Gang; Yang, Yang

    2012-06-20

    The tandem solar cell architecture is an effective way to harvest a broader part of the solar spectrum and make better use of the photonic energy than the single junction cell. Here, we present the design, synthesis, and characterization of a series of new low bandgap polymers specifically for tandem polymer solar cells. These polymers have a backbone based on the benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) units. Alkylthienyl and alkylphenyl moieties were incorporated onto the BDT unit to form BDTT and BDTP units, respectively; a furan moiety was incorporated onto the DPP unit in place of thiophene to form the FDPP unit. Low bandgap polymers (bandgap = 1.4-1.5 eV) were prepared using BDTT, BDTP, FDPP, and DPP units via Stille-coupling polymerization. These structural modifications lead to polymers with different optical, electrochemical, and electronic properties. Single junction solar cells were fabricated, and the polymer:PC(71)BM active layer morphology was optimized by adding 1,8-diiodooctane (DIO) as an additive. In the single-layer photovoltaic device, they showed power conversion efficiencies (PCEs) of 3-6%. When the polymers were applied in tandem solar cells, PCEs over 8% were reached, demonstrating their great potential for high efficiency tandem polymer solar cells.

  20. Double junction photoelectrochemical solar cells based on Cu2ZnSnS4/Cu2ZnSnSe4 thin film as composite photocathode

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Qiang, Y. H.; Zhao, Y. L.; Gu, X. Q.

    2014-02-01

    A solvothermal method was used to synthesize Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanoparticles. CZTS/CZTSe bilayer films have been fabricated via a layer-by-layer blade coating process on the fluorine dope tin oxide (FTO) substrates. We converted conventional dye-sensitized solar cells (DSSCs) into double junction photoelectrochemical solar cells with the replacement of the Pt-coated counter electrode with the as-prepared films as composite photocathodes. Compared with conventional DSSCs, the cells show an increased short circuit current and power conversion efficiency.

  1. Broad spectrum solar cell

    DOEpatents

    Walukiewicz, Wladyslaw; Yu, Kin Man; Wu, Junqiao; Schaff, William J.

    2007-05-15

    An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In.sub.1-xGa.sub.xN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.

  2. Optimization of amorphous silicon double junction solar cells for an efficient photoelectrochemical water splitting device based on a bismuth vanadate photoanode.

    PubMed

    Han, Lihao; Abdi, Fatwa F; Perez Rodriguez, Paula; Dam, Bernard; van de Krol, Roel; Zeman, Miro; Smets, Arno H M

    2014-03-07

    A photoelectrochemical water splitting device (PEC-WSD) was designed and fabricated based on cobalt-phosphate-catalysed and tungsten-gradient-doped bismuth vanadate (W:BiVO4) as the photoanode. A simple and cheap hydrogenated amorphous silicon (a-Si:H) double junction solar cell has been used to provide additional bias. The advantage of using thin film silicon (TF-Si) based solar cells is that this photovoltaic (PV) technology meets the crucial requirements for the PV component in PEC-WSDs based on W:BiVO4 photoanodes. TF-Si PV devices are stable in aqueous solutions, are manufactured by simple and cheap fabrication processes and their spectral response, voltage and current density show an excellent match with the photoanode. This paper is mainly focused on the optimization of the TF-Si solar cell with respect to the remaining solar spectrum transmitted through the W:BiVO4 photoanode. The current matching between the top and bottom cells is studied and optimized by varying the thickness of the a-Si:H top cell. We support the experimental optimization of the current balance between the two sub-cells with simulations of the PV devices. In addition, the impact of the light induced degradation of the a-Si:H double junction, the so-called Staebler-Wronski Effect (SWE), on the performance of the PEC-WSD has been studied. The light soaking experiments on the a-Si:H/a-Si:H double junctions over 1000 hours show that the efficiency of a stand-alone a-Si:H/a-Si:H double junction cell is significantly reduced due to the SWE. Nevertheless, the SWE has a significantly smaller effect on the performance of the PEC-WSD.

  3. Perovskite solar cells: On top of commercial photovoltaics

    NASA Astrophysics Data System (ADS)

    Albrecht, Steve; Rech, Bernd

    2017-01-01

    The efficiency of single-junction solar cells is intrinsically limited and high efficiency multi-junctions are not cost effective yet. Now, semi-transparent perovskite solar cells suggest that low cost multi-junctions could be within reach.

  4. Doping evaluation of InP nanowires for tandem junction solar cells.

    PubMed

    Lindelöw, F; Heurlin, M; Otnes, G; Dagytė, V; Lindgren, D; Hultin, O; Storm, K; Samuelson, L; Borgström, M

    2016-02-12

    In order to push the development of nanowire-based solar cells further using optimized nanowire diameter and pitch, a doping evaluation of the nanowire geometry is necessary. We report on a doping evaluation of n-type InP nanowires with diameters optimized for light absorption, grown by the use of metal-organic vapor phase epitaxy in particle-assisted growth mode using tetraethyltin (TESn) as the dopant precursor. The charge carrier concentration was evaluated using four-probe resistivity measurements and spatially resolved Hall measurements. In order to reach the highest possible nanowire doping level, we set the TESn molar fraction at a high constant value throughout growth and varied the trimethylindium (TMIn) molar fraction for different runs. Analysis shows that the charge carrier concentration in nanowires grown with the highest TMIn molar fraction (not leading to kinking nanowires) results in a low carrier concentration of approximately 10(16) cm(-3). By decreasing the molar fraction of TMIn, effectively increasing the IV/III ratio, the carrier concentration increases up to a level of about 10(19) cm(-3), where it seems to saturate. Axial carrier concentration gradients along the nanowires are found, which can be correlated to a combination of changes in the nanowire growth rate, measured in situ by optical reflectometry, and polytypism of the nanowires observed in transmission electron microscopy.

  5. Doping evaluation of InP nanowires for tandem junction solar cells

    NASA Astrophysics Data System (ADS)

    Lindelöw, F.; Heurlin, M.; Otnes, G.; Dagytė, V.; Lindgren, D.; Hultin, O.; Storm, K.; Samuelson, L.; Borgström, M.

    2016-02-01

    In order to push the development of nanowire-based solar cells further using optimized nanowire diameter and pitch, a doping evaluation of the nanowire geometry is necessary. We report on a doping evaluation of n-type InP nanowires with diameters optimized for light absorption, grown by the use of metal-organic vapor phase epitaxy in particle-assisted growth mode using tetraethyltin (TESn) as the dopant precursor. The charge carrier concentration was evaluated using four-probe resistivity measurements and spatially resolved Hall measurements. In order to reach the highest possible nanowire doping level, we set the TESn molar fraction at a high constant value throughout growth and varied the trimethylindium (TMIn) molar fraction for different runs. Analysis shows that the charge carrier concentration in nanowires grown with the highest TMIn molar fraction (not leading to kinking nanowires) results in a low carrier concentration of approximately 1016 cm-3. By decreasing the molar fraction of TMIn, effectively increasing the IV/III ratio, the carrier concentration increases up to a level of about 1019 cm-3, where it seems to saturate. Axial carrier concentration gradients along the nanowires are found, which can be correlated to a combination of changes in the nanowire growth rate, measured in situ by optical reflectometry, and polytypism of the nanowires observed in transmission electron microscopy.

  6. Enhancing the Photocurrent of Top-Cell by Ellipsoidal Silver Nanoparticles: Towards Current-Matched GaInP/GaInAs/Ge Triple-Junction Solar Cells

    PubMed Central

    Bai, Yiming; Yan, Lingling; Wang, Jun; Su, Lin; Yin, Zhigang; Chen, Nuofu; Liu, Yuanyuan

    2016-01-01

    A way to increase the photocurrent of top-cell is crucial for current-matched and highly-efficient GaInP/GaInAs/Ge triple-junction solar cells. Herein, we demonstrate that ellipsoidal silver nanoparticles (Ag NPs) with better extinction performance and lower fabrication temperature can enhance the light harvest of GaInP/GaInAs/Ge solar cells compared with that of spherical Ag NPs. In this method, appropriate thermal treatment parameters for Ag NPs without inducing the dopant diffusion of the tunnel-junction plays a decisive role. Our experimental and theoretical results confirm the ellipsoidal Ag NPs annealed at 350 °C show a better extinction performance than the spherical Ag NPs annealed at 400 °C. The photovoltaic conversion efficiency of the device with ellipsoidal Ag NPs reaches 31.02%, with a nearly 5% relative improvement in comparison with the device without Ag NPs (29.54%). This function of plasmonic NPs has the potential to solve the conflict of sufficient light absorption and efficient carrier collection in GaInP top-cell devices.

  7. Enhancing the Photocurrent of Top-Cell by Ellipsoidal Silver Nanoparticles: Towards Current-Matched GaInP/GaInAs/Ge Triple-Junction Solar Cells.

    PubMed

    Bai, Yiming; Yan, Lingling; Wang, Jun; Su, Lin; Yin, Zhigang; Chen, Nuofu; Liu, Yuanyuan

    2016-05-25

    A way to increase the photocurrent of top-cell is crucial for current-matched and highly-efficient GaInP/GaInAs/Ge triple-junction solar cells. Herein, we demonstrate that ellipsoidal silver nanoparticles (Ag NPs) with better extinction performance and lower fabrication temperature can enhance the light harvest of GaInP/GaInAs/Ge solar cells compared with that of spherical Ag NPs. In this method, appropriate thermal treatment parameters for Ag NPs without inducing the dopant diffusion of the tunnel-junction plays a decisive role. Our experimental and theoretical results confirm the ellipsoidal Ag NPs annealed at 350 °C show a better extinction performance than the spherical Ag NPs annealed at 400 °C. The photovoltaic conversion efficiency of the device with ellipsoidal Ag NPs reaches 31.02%, with a nearly 5% relative improvement in comparison with the device without Ag NPs (29.54%). This function of plasmonic NPs has the potential to solve the conflict of sufficient light absorption and efficient carrier collection in GaInP top-cell devices.

  8. Low-cost process for P-N junction-type solar cell

    SciTech Connect

    Mooney, J.B.; Cubicciotti, D.D.; Bates, C.W. Jr.

    1980-03-01

    Spray pyrolysis of CuInS/sub 2/ was studied. The concentrations of copper and sulfur in the spray solutions were increased so as to increase the copper content of the films to the stoichiometric level. Although Auger analysis indicates that this was successful, x ray microanalysis has identified the growth of copper-rich crystals on the surfaces of the deposit. Heat treatment in H/sub 2/S did not improve the stoichiometry. The copper-rich crystals were also found on a sample sprayed from a solution with no excess copper. Heterojunctions of glass/SnO/sub 2/(Sb)/CdS/CdTe/carbon(Cu)/Ag-In were prepared with a number of methods used to restrict the junction. The various devices failed to exhibit a diode characteristic or a photo-response. Work on this project is being directed toward understanding the type of junction and how it is formed.

  9. Triple-junction solar cell performance under Fresnel-based concentrators taking into account chromatic aberration and off-axis operation

    NASA Astrophysics Data System (ADS)

    Espinet-González, P.; Mohedano, R.; García, I.; Zamora, P.; Rey-Stolle, I.; Benitez, P.; Algora, C.; Cvetkovic, A.; Hernández, M.; Chaves, J.; Miñano, J. C.; Li, Y.

    2012-10-01

    Concentration photovoltaic (CPV) systems might produce quite uneven irradiance distributions (both on their level and on their spectral distribution) on the solar cell. This effect can be even more evident when the CPV system is slightly off-axis, since they are often designed to assure good uniformity only at normal incidence. The non-uniformities both in absolute irradiance and spectral content produced by the CPV systems, can originate electrical losses in multi-junction solar cells (MJSC). This works is focused on the integration of ray-tracing methods for simulating the irradiance and spectrum maps produced by different optic systems throughout the solar cell surface, with a 3D fully distributed circuit model which simulates the electrical behavior of a state-of-the-art triple-junction solar cell under the different light distributions obtained with ray-tracing. In this study four different CPV system (SILO, XTP, RTP, and FK) comprising Fresnel lenses concentrating sunlight onto the same solar cell are modeled when working on-axis and 0.6 degrees off-axis. In this study the impact of non-uniformities on a CPV system behavior is revealed. The FK outperforms other Fresnel-based CPV systems in both on-axis and off-axis conditions.

  10. Progress toward a 30 percent-efficient, monolithic, three-junction, two-terminal concentrator solar cell for space applications

    NASA Technical Reports Server (NTRS)

    Partain, L. D.; Chung, B.-C.; Virshup, G. F.; Schultz, J. C.; Macmillan, H. F.; Ristow, M. Ladle; Kuryla, M. S.; Bertness, K. A.

    1991-01-01

    Component efficiencies of 0.2/sq cm cells at approximately 100x AMO light concentration and 80 C temperatures are not at 15.3 percent for a 1.9 eV AlGaAs top cell, 9.9 percent for a 1.4 eV GaAs middle cell under a 1.9 eV AlGaAs filter, and 2.4 percent for a bottom 1.0 eV InGaAs cell under a GaAs substrate. The goal is to continue improvement in these performance levels and to sequentially grow these devices on a single substrate to give 30 percent efficient, monolithic, two-terminal, three-junction space concentrator cells. The broad objective is a 30 percent efficient monolithic two-terminal cell that can operate under 25 to 100x AMO light concentrations and at 75 to 100 C cell temperatures. Detailed modeling predicts that this requires three junctions. Two options are being pursued, and both use a 1.9 eV AlGaAs top junction and a 1.4 eV GaAs middle junction grown by a 1 atm OMVPE on a lattice matched substrate. Option 1 uses a low-doped GaAs substrate with a lattice mismatched 1.0 eV InGaAs cell formed on the back of the substrate. Option 2 uses a Ge substrate to which the AlGaAs and GaAs top junctions are lattice matched, with a bottom 0.7 eV Ge junction formed near the substrate interface with the GaAs growth. The projected efficiency contributions are near 16, 11, and 3 percent, respectively, from the top, middle, and bottom junctions.

  11. Cooperative Research between NREL and Solar Junction Corp: Cooperative Research and Development Final Report, CRADA Number CRD-08-306

    SciTech Connect

    Friedman, Daniel

    2015-03-01

    NREL and Solar Junction Corp. will perform cooperative research on materials and devices that are alternatives to standard approaches with the goal of improving solar cell efficiency while lowering cost. The general purpose of this work is to model the performance of a multi-junction concentrator cell of Solar Junction, Inc. design under normal concentrator operating conditions.

  12. Efficient CdSe/p/sup +/n Si tunnel junction photoanode for solar cell

    SciTech Connect

    Pinson, W.E.

    1982-06-01

    The 1.03-V solar photoemf generated by this CdSe/p/sup +/n Si photoanode lends itself to solar storage applications. We present evidence that the 21-mA/cm/sup 2/ short circuit solar photocurrent results from a low resistance tunnel path between the CdSe conduction band and the p/sup +/ Si valence band. We use the dark electron current to calculate that the hole quasi-Fermi level at the CdSe surface of the solar illuminated open circuited photoanode lies 0.16 V below the CdSe corrosion potential. Hence even on open circuit the CdSe surface of the illuminated photoanode will corrode.

  13. Increased efficiency in pn-junction PbS QD solar cells via NaHS treatment of the p-type layer

    NASA Astrophysics Data System (ADS)

    Speirs, Mark J.; Balazs, Daniel M.; Dirin, Dmitry N.; Kovalenko, Maksym V.; Loi, Maria Antonietta

    2017-03-01

    Lead sulfide quantum dot (PbS QD) solar cell efficiencies have improved rapidly over the past years due in large part to intelligent band alignment considerations. A pn-junction can be formed by connecting PbS layers with contrasting ligands. However, the resulting doping concentrations are typically low and cannot be effectively controlled. Here, we present a method of chemically p-doping films of thiol capped PbS QDs. P-n junction solar cells with increased doping in the p-type layer show improved short circuit current and fill factor, leading to an improvement in the power conversion efficiency from 7.1% to 7.6%. By examining Schottky diodes, field effect transistors, and the absorption spectra of treated and untreated PbS QDs, we show that the improved efficiency is due to the increased doping concentration in the thiol capped QD layer and to denser packing of the PbS QD film.

  14. A Silicon Nanocrystal Schottky Junction Solar Cell produced from Colloidal Silicon Nanocrystals

    PubMed Central

    2010-01-01

    Solution-processed semiconductors are seen as a promising route to reducing the cost of the photovoltaic device manufacture. We are reporting a single-layer Schottky photovoltaic device that was fabricated by spin-coating intrinsic silicon nanocrystals (Si NCs) from colloidal suspension. The thin-film formation process was based on Si NCs without any ligand attachment, exchange, or removal reactions. The Schottky junction device showed a photovoltaic response with a power conversion efficiency of 0.02%, a fill factor of 0.26, short circuit-current density of 0.148 mA/cm2, and open-circuit voltage of 0.51 V. PMID:20676200

  15. A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1991-01-01

    An investigation is made into the possibility of providing low resistance contacts to shallow junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity (R sub c) to the 10(exp -5) ohm cm(exp 2) range. We next consider the contact system Au/Au2P3, which has been shown to exhibit as-fabricated R sub c values in the 10(exp -6) ohm cm(exp 2) range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R sub c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R sub c values in the 10(exp -7) ohm cm(exp 2) range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface.

  16. A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1991-01-01

    An investigation is made into the possibility of providing low resistance contacts to shallow junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity (R sub c) to the 10(exp -5) ohm cm(exp 2) range. We next consider the contact system Au/Au2P3 which has been shown to exhibit as-fabricated R sub c values in the 10(exp -6) ohm cm(exp 2) range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R sub c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R sub c values in the 10(exp -7) ohm cm(exp 2) range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface.

  17. Conversion efficiency limits and bandgap designs for multi-junction solar cells with internal radiative efficiencies below unity.

    PubMed

    Zhu, Lin; Mochizuki, Toshimitsu; Yoshita, Masahiro; Chen, Shaoqiang; Kim, Changsu; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-05-16

    We calculated the conversion-efficiency limit ηsc and the optimized subcell bandgap energies of 1 to 5 junction solar cells without and with intermediate reflectors under 1-sun AM1.5G and 1000-sun AM1.5D irradiations, particularly including the impact of internal radiative efficiency (ηint) below unity for realistic subcell materials on the basis of an extended detailed-balance theory. We found that the conversion-efficiency limit ηsc significantly drops when the geometric mean ηint* of all subcell ηint in the stack reduces from 1 to 0.1, and that ηsc degrades linearly to logηint* for ηint* below 0.1. For ηint*<0.1 differences in ηsc due to additional intermediate reflectors became very small if all subcells are optically thick for sun light. We obtained characteristic optimized bandgap energies, which reflect both ηint* decrease and AM1.5 spectral gaps. These results provide realistic efficiency targets and design principles.

  18. Growth and Strain Evaluation of InGaP/InGaAs/Ge Triple-Junction Solar Cell Structures

    NASA Astrophysics Data System (ADS)

    Alhomoudi, Ibrahim A.

    2016-10-01

    Metalorganic chemical vapor deposition (MOCVD) has been used for development of photovoltaic (PV) structures that enable enhanced efficiency for triple-junction solar cell (TJSC) devices. The in-plane strain, lattice match, surface defects, surface morphology, compositional uniformity, threading dislocations (TDs), and depth profile of each layer of the TJSC structure have been examined. The heteroepitaxial layers were found to be near lattice matched to the substrate with excellent coherence between the layers. The analysis explained that the indium gallium phosphide (InGaP) and indium gallium arsenide (InGaAs) layers on germanium (Ge) substrate are a strained structure with purely tetragonal crystalline phase, which indicates that the TJSC structural layers could maintain high crystalline quality. The biaxial in-plane strain in each layer of the TJSC structure is compressive and varies in magnitude for each layer in the structure, being strongly influenced by the Ge substrate and the multiple epilayers of the PV structure. Transmission electron microscopy (TEM) results show no TDs observed over a region with area of 500 nm2, with surface defect density less than 1 × 108 cm-2. No evidence of stacking faults and no visible defects of antiphase domains (APDs) at interfaces were observed, indicating adequate nucleation of epitaxial layers on the substrate and on subsequent growth layers. Furthermore, secondary-ion mass spectrometry (SIMS) analysis showed no significant Ge diffusion from the substrate into the TJSC structure.

  19. Low-cost, high-efficiency organic/inorganic hetero-junction hybrid solar cells for next generation photovoltaic device

    NASA Astrophysics Data System (ADS)

    Pudasaini, P. R.; Ayon, A. A.

    2013-12-01

    Organic/inorganic hybrid structures are considered innovative alternatives for the next generation of low-cost photovoltaic devices because they combine advantages of the purely organic and inorganic versions. Here, we report an efficient hybrid solar cell based on sub-wavelength silicon nanotexturization in combination with the spin-coating of poly (3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS). The described devices were analyzed by collecting current-voltage and capacitance-voltage measurements in order to explore the organic/inorganic heterojunction properties. ALD deposited ultrathin aluminium oxide was used as a junction passivation layer between the nanotextured silicon surface and the organic polymer. The measured interface defect density of the device was observed to decrease with the inclusion of an ultrathin Al2O3 passivation layer leading to an improved electrical performance. This effect is thought to be ascribed to the suppression of charge recombination at the organic/inorganic interface. A maximum power conversion efficiency in excess of 10% has been achieved for the optimized geometry of the device, in spite of lacking an antireflection layer or back surface field enhancement schemes.

  20. On-Orbit Demonstration Of Thin-Film Multi-Junction Solar Cells And Lithium-Ion Capacitors As Bus Components

    NASA Astrophysics Data System (ADS)

    Kukita, Akio; Takahashi, Masato; Shimazaki, Kazunori; Toyota, Hiroyuki; Imaizumi, Mitsuru; Kobayashi, Yuki; Takamoto, Tatsuya; Uno, Masatoshi; Shimada, Takanobu

    2011-10-01

    This paper describes an on-orbit demonstration plan for a lightweight solar panel using thin-film multi-junction (MJ) solar cells and aluminum-laminated lithium-ion capacitors (LICs). Thin-film MJ solar cells such as inverted metamorphic InGaP/GaAs/InGaAs 3J cells have flexibility as well as conversion efficiencies superior to conventional rigid 3J solar cells. A substantial reduction of satellite mass is achieved by the combination of thin-film MJ solar cells and light flexible paddles. An LIC is a hybrid-type capacitor that uses activated carbon as the cathode and carbon material pre-doped with lithium ion as the anode. LICs can be rapidly charged and discharged, and can operate in a wide temperature range for long periods. LICs are therefore suitable for long-term missions such as planetary explorations. Although these devices are very promising, so far there has been no opportunity to demonstrate their use in orbit. A lightweight thin solar panel with thin-film MJ solar cells will be installed on the Small Scientific Satellite Platform for Rapid Investigation and Test-A (SPRINT-A) satellite, which will be launched on the Epsilon launch vehicle in 2013. Utilizing the capacitor-like voltage behavior of LICs, we will employ a simple constant-power charging circuit without feedback control.

  1. Optical coupling from InGaAs subcell to InGaP subcell in InGaP/InGaAs/Ge multi-junction solar cells.

    PubMed

    Shu, G W; Lin, J Y; Jian, H T; Shen, J L; Wang, S C; Chou, C L; Chou, W C; Wu, C H; Chiu, C H; Kuo, H C

    2013-01-14

    Spatially-resolved electroluminescence (EL) images in the triple-junction InGaP/InGaAs/Ge solar cell have been investigated to demonstrate the subcell coupling effect. Upon irradiating the infrared light with an energy below bandgap of the active layer in the top subcell, but above that in the middle subcell, the EL of the top subcell quenches. By analysis of EL intensity as a function of irradiation level, it is found that the coupled p-n junction structure and the photovoltaic effect are responsible for the observed EL quenching. With optical coupling and photoswitching effects in the multi-junction diode, a concept of infrared image sensors is proposed.

  2. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: The study of a new n/p tunnel recombination junction and its application in a-Si:H/μc-Si:H tandem solar cells

    NASA Astrophysics Data System (ADS)

    Li, Gui-Jun; Hou, Guo-Fu; Han, Xiao-Yan; Yuan, Yu-Jie; Wei, Chang-Chun; Sun, Jian; Zhao, Yin; Geng, Xin-Hua

    2009-04-01

    This paper reports that a double N layer (a-Si:H/μc-Si:H) is used to substitute the single microcrystalline silicon n layer (n-μc-Si:H) in n/p tunnel recombination junction between subcells in a-Si:H/μc-Si:H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current-voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si:H/μc-Si:H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.

  3. Diffused junction p(+)-n solar cells in bulk GaAs. I Fabrication and cell performance

    NASA Technical Reports Server (NTRS)

    Bhat, I.; Bhat, K. N.; Mathur, G.; Borrego, J. M.; Ghandhi, S. K.

    1984-01-01

    This paper describes the fabrication of solar cells made by a simple open tube p(+)-diffusion into bulk n-GaAs. In addition, cell performance is provided as an indicator of the quality of bulk GaAs for this application. Initial results using this technique (12.2 percent efficiency at AM1 for 0.5 sq cm cells) are promising, and indicate directions for materials improvement. It is shown that the introduction of the diffusant (zinc) with point defects significantly affects the material properties and results in an increase in current capability.

  4. Commercialization of New Lattice-Matched Multi-Junction Solar Cells Based on Dilute Nitrides: July 8, 2010 - March 7, 2012

    SciTech Connect

    Herb, J.

    2012-04-01

    Final Technical Progress Report for PV Incubator subcontract NAT-0-99013-03. The overall objective of this Incubator subcontract was to complete the work necessary to make commercial ready solar cells using the dilute nitride technology. The specific objectives of this program were aimed at completing the development of a triple-junction solar cell that incorporates a GaInNAs {approx}1eV subcell to the point of commercial readiness, and determining the cell reliability and, if necessary, identifying and eliminating process or material related issues that lead to early-life cell failures. There were three major objectives for Phase 1, each of which focuses on a key element of the solar cell that determines its performance in a commercial CPV system. One objective was to optimize the quality and performance of the key individual components making up the solar cell structure and then to optimize the integration of these components into a complete triple-junction cell. A second objective was to design and test anti-reflective coating that maximizes the light coupled into a 3J cell with a {approx}1 eV bottom cell bandgap. The third objective was to develop Highly Accelerated Life Tests (HALT) protocols and tools for identifying and correcting potential reliability problems. The Phase 2 objectives were a continuation of the work begun in Phase 1 but aimed at optimizing cell performance for commercial requirements. Phase 2 had four primary objectives: (1) develop a glass-matched anti-reflective coating (ARC) and optimize the cell/ARC to give good performance at 60C operating temperature, (2) optimize the cell for good operation at 60C and high concentration, and (3) complete the light biased HALT system and use it to determine what, if any, failures are observed, and (4) determine the reliability limits of the optimized cell.

  5. Multi-junction Thin-film Solar Cells on Flexible Substrates for Space Power

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Smith, Mark; Scofield, John H.; Dickman, John E.; Lush, Gregory B.; Morel, Donald L.; Ferekides, Christos; Dhere, Neelkanth G.

    2002-01-01

    The ultimate objective of the thin-film program at NASA GRC is development of a 20 percent AM0 thin-film device technology with high power/weight ratio. Several approaches are outlined to improve overall device efficiency and power/weight ratio. One approach involves the use of very lightweight flexible substrates such as polyimides (i.e., Kapton(Trademark)) or metal foil. Also, a compound semiconductor tandem device structure that can meet this objective is proposed and simulated using Analysis of Microelectronic and Photonic Structures (AMPS). AMPS modeling of current devices in tandem format indicate that AM0 efficiencies near 20 percent can be achieved. And with improvements in materials, efficiencies approaching 25 percent are achievable. Several important technical issues need to be resolved to realize these complex devices: development of a wide bandgap material with good electronic properties, development of transparent contacts, and targeting a 2-terminal device structure (with more complicated processing and tunnel junction) or 4-terminal device. Recent progress in the NASA GRC program is outlined.

  6. Impact of dislocation densities on n+/p and p+/n junction GaAs diodes and solar cells on SiGe virtual substrates

    NASA Astrophysics Data System (ADS)

    Andre, C. L.; Wilt, D. M.; Pitera, A. J.; Lee, M. L.; Fitzgerald, E. A.; Ringel, S. A.

    2005-07-01

    Recent experimental measurements have shown that in GaAs with elevated threading dislocation densities (TDDs) the electron lifetime is much lower than the hole lifetime [C. L. Andre, J. J. Boeckl, D. M. Wilt, A. J. Pitera, M. L. Lee, E. A. Fitzgerald, B. M. Keyes, and S. A. Ringel, Appl. Phys. Lett. 84, 3884 (2004)]. This lower electron lifetime suggests an increase in depletion region recombination and thus in the reverse saturation current (J0 for an n+/p diode compared with a p+/n diode at a given TDD. To confirm this, GaAs diodes of both polarities were grown on compositionally graded Ge /Si1-xGex/Si (SiGe) substrates with a TDD of 1×106cm-2. It is shown that the ratio of measured J0 values is consistent with the inverse ratio of the expected lifetimes. Using a TDD-dependent lifetime in solar cell current-voltage models we found that the Voc, for a given short-circuit current, also exhibits a poorer TDD tolerance for GaAs n+/p solar cells compared with GaAs p+/n solar cells. Experimentally, the open-circuit voltage (Voc) for the n+/p GaAs solar cell grown on a SiGe substrate with a TDD of ˜1×106cm-2 was ˜880mV which was significantly lower than the ˜980mV measured for a p+/n GaAs solar cell grown on SiGe at the same TDD and was consistent with the solar cell modeling results reported in this paper. We conclude that p+/n polarity GaAs junctions demonstrate superior dislocation tolerance than n+/p configured GaAs junctions, which is important for optimization of lattice-mismatched III-V devices.

  7. Annealed single-crystal cadmium selenide electrodes in liquid junction solar cells

    SciTech Connect

    Wessel, S.; Colbow, K.; Mackintosh, A.

    1984-12-01

    I-V characteristics, voltage dependence of the quantum efficiency, and spectral response were compared for annealed single-crystal CdSe photoanodes. Annealing in cadmium atmosphere improved the overall solar response considerably, while annealing under vacuum revealed a poor response for photon energies larger than 1.8 eV and a high quantum efficiency for near-bandgap energies. This behavior may be attributed to electron-hole pai generation from interbandgap states and a large density of minority carrier recombination centers near the crystal surface, owing to a high nonstoichiometry and a selenium layer at the surface. Annealing in selenium atmosphere resulted in very poor solar response caused by compensation. Simultaneous illumination of the electrodes with a He-Ne lase strongly enhanced the quantum efficiency for vacuum-annealed crystals for near-bandgap photons. We attribute this to electron trapping in the selenium-rich surface, with a resulting increase in depletion-layer width in the cadmium selenide.

  8. Thermally stable, low resistance contact systems for use with shallow junction p(+) nn(+) and n(+)pp(+) InP solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Fatemi, N. S.; Hoffman, R. W.

    1995-01-01

    Two contact systems for use on shallow junction InP solar cells are described. The feature shared by these two contact systems is the absence of the metallurgical intermixing that normally takes place between the semiconductor and the contact metallization during the sintering process. The n(+)pp(+) cell contact system, consisting of a combination of Au and Ge, not only exhibits very low resistance in the as-fabricated state, but also yields post-sinter resistivity values of 1(exp -7) ohms-sq cm, with effectively no metal-InP interdiffusion. The n(+)pp(+)cell contact system, consisting of a combination of Ag and Zn, permits low resistance ohmic contact to be made directly to a shallow junction p/n InP device without harming the device itself during the contacting process.

  9. The distance temperature map as method to analyze the optical properties of Fresnel lenses and their interaction with multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Hornung, Thorsten; Kiefel, Peter; Nitz, Peter

    2015-09-01

    The optical efficiency of Fresnel lens based solar concentrators varies with the temperature of the Fresnel lens. The dependency of any quantity of interest (e.g. optical efficiency) on Fresnel lens temperature can be visualized by 2d color plots that simultaneously show it as a function of the distance between solar cell and Fresnel lens and as a function of Fresnel lens temperature. This visualization, which is called DTmap, strongly facilitates the analysis of the thermal behavior of a Fresnel lens and the optimization of module height. Based on DTmaps we reveal and discuss serveral details of the thermal behavior of silicone on glass (SOG) Fresnel lenses. In addition, the DTmap is shown for the efficiency of a system consisting of a Fresnel lens and a lattice matched three-junction and a four-junction solar cell. The results demonstrate that the interaction of the concentrator optics and the solar cell is not trivial and may also be studied using DTmaps.

  10. Minimum entropy principle-based solar cell operation without a pn-junction and a thin CdS layer to extract the holes from the emitter

    NASA Astrophysics Data System (ADS)

    Böer, Karl W.

    2016-10-01

    The solar cell does not use a pn-junction to separate electrons from holes, but uses an undoped CdS layer that is p-type inverted when attached to a p-type collector and collects the holes while rejecting the backflow of electrons and thereby prevents junction leakage. The operation of the solar cell is determined by the minimum entropy principle of the cell and its external circuit that determines the electrochemical potential, i.e., the Fermi-level of the base electrode to the operating (maximum power point) voltage. It leaves the Fermi level of the metal electrode of the CdS unchanged, since CdS does not participate in the photo-emf. All photoelectric actions are generated by the holes excited from the light that causes the shift of the quasi-Fermi levels in the generator and supports the diffusion current in operating conditions. It is responsible for the measured solar maximum power current. The open circuit voltage (Voc) can approach its theoretical limit of the band gap of the collector at 0 K and the cell increases the efficiency at AM1 to 21% for a thin-film CdS/CdTe that is given as an example here. However, a series resistance of the CdS forces a limitation of its thickness to preferably below 200 Å to avoid unnecessary reduction in efficiency or Voc. The operation of the CdS solar cell does not involve heated carriers. It is initiated by the field at the CdS/CdTe interface that exceeds 20 kV/cm that is sufficient to cause extraction of holes by the CdS that is inverted to become p-type. Here a strong doubly charged intrinsic donor can cause a negative differential conductivity that switches-on a high-field domain that is stabilized by the minimum entropy principle and permits an efficient transport of the holes from the CdTe to the base electrode. Experimental results of the band model of CdS/CdTe solar cells are given and show that the conduction bands are connected in the dark, where the electron current must be continuous, and the valence bands are

  11. Study of the electrical parameters degradation of GaAs sub-cells for triple junction space solar cells by computer simulation

    NASA Astrophysics Data System (ADS)

    Cappelletti, M. A.; Casas, G. A.; Morales, D. M.; Hasperue, W.; Blancá, E. L. Peltzer y.

    2016-11-01

    In this paper, a theoretical study of the electrical parameters degradation of different n-type GaAs sub-cells for InGaP/GaAs/Ge triple junction solar cells irradiated with 1 and 5 MeV electrons has been performed by means of computer simulation. Effects of base carrier concentration upon the maximum power point, short-circuit current, open circuit voltage, diffusion current, recombination current and series resistance of these devices have been researched using the displacement damage dose method, the one-dimensional PC1D device modeling program and a home-made numerical code based on genetic algorithms. The radiative recombination lifetime, damage constant for minority-carrier lifetime and carrier removal rate models for GaAs sub-cells have been used in the simulations. An analytical model has been proposed, which is useful to describe the radiation-induced degradation of diffusion current, recombination current and series resistance. Results obtained in this work can be used to predict the radiation resistance of solar cells over a wide range of energies.

  12. GaInP/GaAs tandem solar cells with highly Te- and Mg-doped GaAs tunnel junctions grown by MBE

    NASA Astrophysics Data System (ADS)

    Zheng, Xin-He; Liu, San-Jie; Xia, Yu; Gan, Xing-Yuan; Wang, Hai-Xiao; Wang, Nai-Ming; Yang, Hui

    2015-10-01

    We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction (TJ) with using tellurium (Te) and magnesium (Mg) as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy (MBE) at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 mA/cm2, but a low open-circuit voltage range of 1.4 V˜1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy (SIMS) analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended GaAs n++/p++ junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ˜ 2.5 × 1020 in GaAs could cause a lattice strain of 10-3 in magnitude and thus a surface roughening, which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell. Project supported by the SINANO-SONY Joint Program (Grant No. Y1AAQ11001), the National Natural Science Foundation of China (Grant No. 61274134), the USCB Start-up Program (Grant No. 06105033), and the International Cooperation Projects of Suzhou City, China (Grant No. SH201215).

  13. The effect of the optical system on the electrical performance of III-V concentrator triple junction solar cells

    NASA Astrophysics Data System (ADS)

    Schultz, R. D.; van Dyk, E. E.; Vorster, F. J.

    2016-01-01

    High Concentrated Photovoltaic (H-CPV) technologies utilize relatively inexpensive reflective and refractive optical components for concentration to achieve high energy yield. The electrical performance of H-CPV systems is, however, dependent on the properties and configuration of the optical components. The focus of this paper is to summarize the effect of the properties of the optical system on the electrical performance of a Concentrator Triple Junction (CTJ) InGaP/InGaAs/Ge cell. Utilizing carefully designed experiments that include spectral measurements and intensity profiles in the optical plane of the CTJ cell, the influence of photon absorption, Fresnel lens properties and chromatic aberration created by the optical system on the electrical performance of a CTJ cell is shown. From the results obtained, it is concluded that good characterization and understanding of the optical system's properties may add to improved design of future multi-junction devices.

  14. Compound biomimetic structures for efficiency enhancement of Ga₀.₅In₀.₅P/GaAs/Ge triple-junction solar cells.

    PubMed

    Hung, Mu-Min; Han, Hau-Vei; Hong, Chung-Yu; Hong, Kuo-Hsuan; Yang, Tung-Ting; Yu, Peichen; Wu, Yu-Rue; Yeh, Hong-Yih; Huang, Hong-Cheng

    2014-03-10

    Biomimetic nanostructures have shown to enhance the optical absorption of Ga₀.₅In₀.₅P/GaAs/Ge triple junction solar cells due to excellent antireflective (AR) properties that, however, are highly dependent on their geometric dimensions. In practice, it is challenging to control fabrication conditions which produce nanostructures in ideal periodic arrangements and with tapered side-wall profiles, leading to sacrificed AR properties and solar cell performance. In this work, we introduce compound biomimetic nanostructures created by depositing a layer of silicon dioxide (SiO₂) on top of titanium dioxide (TiO₂) nanostructures for triple junction solar cells. The device exhibits photogenerated current and power conversion efficiency that are enhanced by ~8.9% and ~6.4%, respectively, after deposition due to their improved antireflection characteristics. We further investigate and verify the optical properties of compound structures via a rigorous coupled wave analysis model. The additional SiO₂ layer not only improves the geometric profile, but also serves as a double-layer dielectric coating. It is concluded that the compound biomimetic nanostructures exhibit superior AR properties that are relatively insensitive to fabrication constraints. Therefore, the compound approach can be widely adopted for versatile optoelectronic devices and applications.

  15. Compound biomimetic structures for efficiency enhancement of Ga(0.5)In(0.5)P/GaAs/Ge triple-junction solar cells.

    PubMed

    Hung, Mu-Min; Han, Hau-Vei; Hong, Chung-Yu; Hong, Kuo-Hsuan; Yang, Tung-Ting; Yu, Peichen; Wu, Yu-Rue; Yeh, Hong-Yih; Huang, Hong-Cheng

    2014-03-10

    Biomimetic nanostructures have shown to enhance the optical absorption of Ga(0.5)In(0.5)P/GaAs/Ge triple junction solar cells due to excellent antireflective (AR) properties that, however, are highly dependent on their geometric dimensions. In practice, it is challenging to control fabrication conditions which produce nanostructures in ideal periodic arrangements and with tapered side-wall profiles, leading to sacrificed AR properties and solar cell performance. In this work, we introduce compound biomimetic nanostructures created by depositing a layer of silicon dioxide (SiO(2)) on top of titanium dioxide (TiO(2)) nanostructures for triple junction solar cells. The device exhibits photogenerated current and power conversion efficiency that are enhanced by ~8.9% and ~6.4%, respectively, after deposition due to their improved antireflection characteristics. We further investigate and verify the optical properties of compound structures via a rigorous coupled wave analysis model. The additional SiO(2) layer not only improves the geometric profile, but also serves as a double-layer dielectric coating. It is concluded that the compound biomimetic nanostructures exhibit superior AR properties that are relatively insensitive to fabrication constraints. Therefore, the compound approach can be widely adopted for versatile optoelectronic devices and applications.

  16. Electrochemically synthesized broadband antireflective and hydrophobic GaOOH nanopillars for III-V InGaP/GaAs/Ge triple-junction solar cell applications.

    PubMed

    Leem, Jung Woo; Lee, Hee Kwan; Jun, Dong-Hwan; Heo, Jonggon; Park, Won-Kyu; Park, Jin-Hong; Yu, Jae Su

    2014-03-10

    We report the efficiency enhancement of III-V InGaP/GaAs/ Ge triple-junction (TJ) solar cells using a novel structure, i.e., vertically-oriented gallium oxide hydroxide (GaOOH) nanopillars (NPs), as an antireflection coating. The optical reflectance properties of rhombus-shaped GaOOH NPs, which were synthesized by a simple, low-cost, and large-scalable electrochemical deposition method, were investigated, together with a theoretical analysis using the rigorous coupled-wave analysis method. For the GaOOH NPs, the solar weighted reflectance of ~8.5% was obtained over a wide wavelength range of 300-1800 nm and their surfaces exhibited a high water contact angle of ~130° (i.e., hydrophobicity). To simply demonstrate the feasibility of device applications, the GaOOH NPs were incorporated into a test-grown InGaP/GaAs/Ge TJ solar cell structure. For the InGaP/GaAs/Ge TJ solar cell with broadband antireflective GaOOH NPs, the conversion efficiency (η) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., η~13%).

  17. Investigation of Junction Properties in CdS/CdTe Solar Cells and Their Correlation to Device Properties: Preprint

    SciTech Connect

    Dhere, R. G.; Zhang, Y.; Romero, M. J.; Asher, S. E.; Young, M.; To, B.; Noufi, R.; Gessert, T. A.

    2008-05-01

    Secondary-ion mass spectrometry analysis of the CdS/CdTe interface shows that S diffusion in CdTe increases with substrate temperature and CdCl2 heat treatment. There is also an accumulation of Cl at the interface for CdCl2-treated samples. Modulated photo-reflectance studies shows that devices with CdCl2 heat treatment and open-circuit voltage (Voc) of 835 mV have a distinct high electric-field region in the layer with bandgap of 1.45 eV. Electron-beam induced current measurements reveal a one-sided junction for high Voc devices. The nature of the junction changes with processing. For heterojunction devices, the depletion region includes the highly defective CdS/CdTe interface, which would increase the recombination current and consequently the dark current, leading to lower Voc. In the case of CdCl2-treated cells, the n+-p junction and its high electric-field results in the junction between structurally compatible CdTe and the Te-rich CdSTe alloy, and thus, in higher Voc.

  18. Investigation of the radiation resistance of triple-junction a-Si:H alloy solar cells irradiated with 1.00 MeV protons

    NASA Technical Reports Server (NTRS)

    Lord, Kenneth R., II; Walters, Michael R.; Woodyard, James R.

    1993-01-01

    The effect of 1.00 MeV proton irradiation on hydrogenated amorphous silicon alloy triple-junction solar cells is reported for the first time. The cells were designed for radiation resistance studies and included 0.35 cm(sup 2) active areas on 1.0 by 2.0 cm(sup 2) glass superstrates. Three cells were irradiated through the bottom contact at each of six fluences between 5.10E12 and 1.46E15 cm(sup -2). The effect of the irradiations was determined with light current-voltage measurements. Proton irradiation degraded the cell power densities from 8.0 to 98 percent for the fluences investigated. Annealing irradiated cells at 200 C for two hours restored the power densities to better than 90 percent. The cells exhibited radiation resistances which are superior to cells reported in the literature for fluences less than 1E14 cm(sup -2).

  19. High-efficiency, deep-junction, epitaxial InP solar cells on (100) and (111)B InP substrates

    NASA Technical Reports Server (NTRS)

    Venkatasubramanian, R.; Timmons, M. L.; Hutchby, J. A.; Walters, Robert J.; Summers, Geoffrey P.

    1994-01-01

    We report on the development and performance of deep-junction (approximately 0.25 micron), graded-emitter-doped, n(sup +)-p InP solar cells grown by metallorganic chemical vapor deposition (MOCVD). A novel, diffusion-transport process for obtaining lightly-doped p-type base regions of the solar cell is described. The I-V data and external quantum-efficiency response of these cells are presented. The best active-area AMO efficiency for these deep-junction cells on (100)-oriented InP substrates is 16.8 percent, with a J(sub SC) of 31.8 mA/sq cm, a V(sub OC) of 0.843 V, and a fill-factor of 0.85. By comparison, the best cell efficiency on the (111)B-oriented InP substrates was 15.0 percent. These efficiency values for deep-junction cells are encouraging and compare favorably with performance of thin-emitter (0.03 micron) epitaxial cells as well as that of deep-emitter diffused cells. The cell performance and breakdown voltage characteristics of a batch of 20 cells on each of the orientations are presented, indicating the superior breakdown voltage properties and other characteristics of InP cells on the (111)B orientation. Spectral response, dark I-V data, and photoluminescence (PL) measurements on the InP cells are presented with an analysis on the variation in J(sub SC) and V(sub OC) of the cells. It is observed, under open-circuit conditions, that lower-V(sub OC) cells exhibit higher band-edge PL intensity for both the (100) and (111)B orientations. This anomalous behavior suggests that radiative recombination in the heavily-doped n(sup +)-InP emitter may be detrimental to achieving higher V(sub OC) in n(sup +)-p InP solar cells.

  20. Nanorainforest solar cells based on multi-junction hierarchical p-Si/n-CdS/n-ZnO nanoheterostructures.

    PubMed

    Wang, Wei; Zhao, Qing; Laurent, Kevin; Leprince-Wang, Y; Liao, Zhi-Min; Yu, Dapeng

    2012-01-07

    Solar cells based on one-dimensional nanostructures have recently emerged as one of the most promising candidates to achieve high-efficiency solar energy conversion due to their reduced optical reflection, enhanced light absorption, and enhanced carrier collection. In nature, the rainforest, consisting of several stereo layers of vegetation, is the highest solar-energy-using ecosystem. Herein, we gave an imitation of the rainforest configuration in nanostructure-based solar cell design. Novel multi-layer nanorainforest solar cells based on p-Si nanopillar array/n-CdS nanoparticles/n-ZnO nanowire array heterostructures were achieved via a highly accessible, reproducible and controllable fabrication process. By choosing materials with appropriate bandgaps, an efficient light absorption and enhanced light harvesting were achieved due to the wide range of the solar spectrum covered. Si nanopillar arrays were introduced as direct conduction pathways for photon-generated charges' efficient collection and transport. The unique strategy using PMMA as a void-filling material to obtain a continuous, uniform and low resistance front electrode has significantly improved the overall light conversion efficiency by two orders of magnitude. These results demonstrate that nanorainforest solar cells, along with wafer-scale, low-cost and easily controlled processing, open up substantial opportunities for nanostructure photovoltaic devices.

  1. Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

    SciTech Connect

    Müller, Ralph Schrof, Julian; Reichel, Christian; Benick, Jan; Hermle, Martin

    2014-09-08

    The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implanted phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.

  2. Results of some initial space qualification testing on triple junction a-Si and CuInSe2 thin film solar cells

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.; Anspaugh, Bruce E.

    1993-01-01

    A series of environmental tests were completed on one type of triple junction a-Si and two types of CuInSe2 thin film solar cells. The environmental tests include electron irradiation at energies of 0.7, 1.0, and 2.0 MeV, proton irradiation at energies of 0.115, 0.24, 0.3, 0.5, 1.0, and 3.0 MeV, post-irradiation annealing at temperatures between 20 C and 60 C, long term exposure to air mass zero (AM0) photons, measurement of the cells as a function of temperature and illumination intensity, and contact pull strength tests. As expected, the cells are very resistant to electron and proton irradiation. However, when a selected cell type is exposed to low energy protons designed to penetrate to the junction region, there is evidence of more significant damage. A significant amount of recovery was observed after annealing in several of the cells. However, it is not permanent and durable, but merely a temporary restoration, later nullified with additional irradiation. Contact pull strengths measured on the triple junction a-Si cells averaged 667 grams, and pull strengths measured on the Boeing CuInSe2 cells averaged 880 grams. Significant degradation of all cell types was observed after exposure to a 580 hour photon degradation test, regardless of whether the cells had been unirradiated or irradiated (electrons or protons). Although one cell from one manufacturer lost approximately 60 percent of its power after the photon test, several other cells from this manufacturer did not degrade at all.

  3. Vertical Junction Solar Cells.

    DTIC Science & Technology

    1985-12-20

    during the cure cycle. CAUTION: CV-2567 CURING AGENT MAY CAUSE SKIN AND EYE IRRITATION. IN CASE OF EYE CONTACT, IRRIGATE WITH WATER IMMEDIATELY AND GET...a diffusion pumped vacuum chamber with the pressure monitored by an ionization gauge. The heating was supplied by tungsten halogen lamps and measured...environmental protection- 93-500 space-grade encapsulant arej 24 hours at 125 C (275 F) and less low water absorption (less than useable over a wide temperature

  4. Characterization and modeling of screen-printed metal insulator semiconductor tunnel junctions for integrated bypass functionality in crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Thaidigsmann, Benjamin; Lohmüller, Elmar; Fertig, Fabian; Clement, Florian; Wolf, Andreas

    2013-06-01

    This work investigates sintered, screen-printed silver contacts on lowly doped p-type silicon with different intermediate dielectric layer systems using scanning electron microscopy and dark current-voltage measurements. The data reveal electron tunneling through a thin insulating layer as the most probable transport mechanism. A model based on Fowler-Nordheim and direct tunneling is presented that allows for the description of reverse current-voltage characteristics and the extraction of effective contact properties. The investigated screen-printed metal insulator semiconductor structures are proposed as solar cell integrated bypass that reduces the risk of hot spot generation and power loss during partial shading of a module. Furthermore, the integrated bypass approach enables the fabrication of solar cells from silicon material that tends to show early breakdown of the p-n-junction.

  5. Determination of the Electrical Junction in Cu(In, Ga)Se2 and Cu2ZnSnSe4 Solar Cells with 20-nm Spatial Resolution

    SciTech Connect

    Xiao, Chuanxiao; Jiang, Chun-Sheng; Moutinho, Helio; Levi, Dean; Yan, Yanfa; Gorman, Brian; Al-Jassim, Mowafak

    2016-11-21

    We located the electrical junction (EJ) of Cu(In, Ga)Se2 (CIGS) and Cu2ZnSnSe4 (CZTS) solar cells with ~20-nm accuracy using a scanning capacitance spectroscopy (SCS) technique. A procedure was developed to prepare the cross-sectional samples and grow critical high-quality insulating layers for the SCS measurement. We found that CIGS has a buried homojunction with the EJ located at ~40 nm inside the CIGS/CdS interface. An n-type CIGS was probed in the region 10-30 nm away from the interface. By contrast, the CZTS/CdS cells have a heterointerface junction with a shallower EJ (~20 nm) than CIGS. The EJ is ~20 nm from the CZTS/CdS interface, which is consistent with asymmetrical carrier concentrations of the p-CZTS and n-CdS in a heterojunction cell. The unambiguous determination of the junction locations helped explain the large open circuit voltage difference between the state-of-the-art devices of CIGS and CZTS.

  6. Designing of 1 eV GaNAs/GaInAs superlattice subcell in current-matched four-junction solar cell

    NASA Astrophysics Data System (ADS)

    Haixiao, Wang; Xinhe, Zheng; Xingyuan, Gan; Naiming, Wang; Hui, Yang

    2016-01-01

    A reasonably-thick GaNAs/GaInAs superlattice could be an option as a roughly 1 eV subcell to achieve high-efficiency multi-junction solar cells on a lattice-matched Ge substrate. A detailed consideration of a high-efficiency design for a GaInP/GaAs/1 eV/Ge device is presented. Calculations have been done for this structure to obtain the confined energies of the electrons and holes by utilizing the Kronig-Penney model, as well as the absorption coefficient and thereby the external quantum efficiency. The effect of well layers, GaNAs or GaInAs, on the absorption and photocurrent density under the AM 1.5 condition is discussed in order to realize a requirement of current matching in the four-junction solar cells. The management of these considerations implies the feasibility of the GaNAs/GaInAs superlattice subcell design to improve the overall conversion efficiency of lattice matched GaInP/GaAs/1 eV/Ge cells. Project supported by the National Natural Science Foundation of China (No. 61274134) and the International Cooperation Program of Suzhou, China (No. SH201215).

  7. Photovoltaic solar cell

    DOEpatents

    Nielson, Gregory N.; Gupta, Vipin P.; Okandan, Murat; Watts, Michael R.

    2015-09-08

    A photovoltaic solar concentrator is disclosed with one or more transverse-junction solar cells (also termed point contact solar cells) and a lens located above each solar cell to concentrate sunlight onto the solar cell to generate electricity. Piezoelectric actuators tilt or translate each lens to track the sun using a feedback-control circuit which senses the electricity generated by one or more of the solar cells. The piezoelectric actuators can be coupled through a displacement-multiplier linkage to provide an increased range of movement of each lens. Each lens in the solar concentrator can be supported on a frame (also termed a tilt plate) having three legs, with the movement of the legs being controlled by the piezoelectric actuators.

  8. The electronic structure of metal oxide/organo metal halide perovskite junctions in perovskite based solar cells.

    PubMed

    Dymshits, Alex; Henning, Alex; Segev, Gideon; Rosenwaks, Yossi; Etgar, Lioz

    2015-03-03

    Cross-sections of a hole-conductor-free CH3NH3PbI3 perovskite solar cell were characterized with Kelvin probe force microscopy. A depletion region width of about 45 nm was determined from the measured potential profiles at the interface between CH3NH3PbI3 and nanocrystalline TiO2, whereas a negligible depletion was measured at the CH3NH3PbI3/Al2O3 interface. A complete solar cell can be realized with the CH3NH3PbI3 that functions both as light harvester and hole conductor in combination with a metal oxide. The band diagrams were estimated from the measured potential profile at the interfaces, and are critical findings for a better understanding and further improvement of perovskite based solar cells.

  9. The electronic structure of metal oxide/organo metal halide perovskite junctions in perovskite based solar cells

    PubMed Central

    Dymshits, Alex; Henning, Alex; Segev, Gideon; Rosenwaks, Yossi; Etgar, Lioz

    2015-01-01

    Cross-sections of a hole-conductor-free CH3NH3PbI3 perovskite solar cell were characterized with Kelvin probe force microscopy. A depletion region width of about 45 nm was determined from the measured potential profiles at the interface between CH3NH3PbI3 and nanocrystalline TiO2, whereas a negligible depletion was measured at the CH3NH3PbI3/Al2O3 interface. A complete solar cell can be realized with the CH3NH3PbI3 that functions both as light harvester and hole conductor in combination with a metal oxide. The band diagrams were estimated from the measured potential profile at the interfaces, and are critical findings for a better understanding and further improvement of perovskite based solar cells. PMID:25731963

  10. Flexible CuS nanotubes-ITO film Schottky junction solar cells with enhanced light harvesting by using an Ag mirror.

    PubMed

    Wu, Chunyan; Zhang, Zihan; Wu, Yiliang; Lv, Peng; Nie, Biao; Luo, Linbao; Wang, Li; Hu, Jigang; Jie, Jiansheng

    2013-02-01

    Here we report the fabrication of a novel photovoltaic device based on CuS nanotubes (CuSNTs) and indium tin oxide (ITO) Schottky junctions. Large-quantity synthesis of CuSNTs was accomplished via a solution-based sacrificial template method under moderate conditions, while ITO Schottky contacts were fabricated via micro-fabrication and pulsed laser deposition (PLD). Upon light illumination, CuSNTs-ITO Schottky junctions exhibited pronounced photovoltaic behavior, giving rise to a power conversion efficiency of 1.17% on a conventional SiO(2)/Si substrate. Furthermore, by utilizing PET as the substrate, transparent and flexible CuSNTs-ITO solar cells were constructed and showed performance close to their device counterparts on a rigid substrate. Notably, it was found that the flexible devices were robust against tensile strain and could stand a bending angle up to ∼95°. To enhance the light absorption of the devices, an Ag mirror layer was deposited on the rear side of the PET substrate so as to allow multiple reflection and absorption of the incident light. As a result, the flexible devices showed a substantial performance improvement, yielding an efficiency of ∼2%. Our results demonstrate that low-cost and environmentally friendly CuSNTs-ITO solar cells are promising candidates for new-generation photovoltaic devices.

  11. Photovoltaic solar cell

    DOEpatents

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2013-11-26

    A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electicity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

  12. Photovoltaic solar cell

    DOEpatents

    Nielson, Gregory N; Cruz-Campa, Jose Luis; Okandan, Murat; Resnick, Paul J

    2014-05-20

    A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electricity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

  13. Comparative investigation of InGaP/InGaAs/Ge triple-junction solar cells using different Te-doped InGaP layers in tunnel junctions

    NASA Astrophysics Data System (ADS)

    Jung, Sang Hyun; Kim, Chang Zoo; Kim, Youngjo; Jun, Dong Hwan; Kang, Ho Kwan; Kim, Hogyoung

    2016-03-01

    Heavily tellurium (Te)-doped InGaP layers in tunnel junctions (TJs) grown by using metalorganic chemical vapor deposition (MOCVD) were investigated to improve the device performance of InGaP/InGaAs/Ge triple-junction solar cells. Three different doping techniques were employed to grow the Te-doped InGaP layers in the TJ; Te doping, Te and Si co-doping and Te pre-doping. Compared to other samples, the external quantum efficiency (EQE) profiles in the InGaP top cell were found to be higher for the sample with Te pre-doping. Under a concentrated light condition, higher fill factor (FF) and conversion efficiency were also observed for the sample with Te pre-doping. These indicate that the crystalline qualities of the upper TJ, composed of a p-GaAs/n-InGaP TJ, and the InGaP top cell were improved by using the Te pre-doping method.

  14. 0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1-eV)/GaInAs(0.7-eV) Four-Junction Solar Cell: Preprint

    SciTech Connect

    Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W.; Kurtz, S. R.

    2006-05-01

    We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga0.5In0.5P/GaAs/Ga0.75In0.25As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga0.75In0.25As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap GaxIn1-xAs fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the GaxIn1-xAs fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.

  15. Study on limiting efficiencies of a-Si:H/μc-Si:H-based single-nanowire solar cells under single and tandem junction configurations

    SciTech Connect

    Zhai, Xiongfei; Cao, Guoyang; Wu, Shaolong E-mail: xfli@suda.edu.cn; Shang, Aixue; Li, Xiaofeng E-mail: xfli@suda.edu.cn

    2015-11-02

    Detailed balance calculations are presented for a-Si:H/μc-Si:H-based single- and tandem-junction single-nanowire solar cells (S- and T-SNSCs). Our study is based on three-dimensional finite-element electromagnetic simulation and thermodynamic balanced analysis, which includes radiative and Auger recombinations simultaneously. We quantify and compare the limiting short-circuit current densities, open-circuit voltages, and light-conversion efficiencies of these highly compact photovoltaic cells, addressing especially the effect of Auger recombination on the open-circuit voltages of SNSCs. Results show that tandem design leads to much higher light-conversion capability than μc-Si:H S-SNSCs, but exhibits superior performance than a-Si:H S-SNSCs only for cells with large radii.

  16. Study on limiting efficiencies of a-Si:H/μc-Si:H-based single-nanowire solar cells under single and tandem junction configurations

    NASA Astrophysics Data System (ADS)

    Zhai, Xiongfei; Cao, Guoyang; Wu, Shaolong; Shang, Aixue; Li, Xiaofeng

    2015-11-01

    Detailed balance calculations are presented for a-Si:H/μc-Si:H-based single- and tandem-junction single-nanowire solar cells (S- and T-SNSCs). Our study is based on three-dimensional finite-element electromagnetic simulation and thermodynamic balanced analysis, which includes radiative and Auger recombinations simultaneously. We quantify and compare the limiting short-circuit current densities, open-circuit voltages, and light-conversion efficiencies of these highly compact photovoltaic cells, addressing especially the effect of Auger recombination on the open-circuit voltages of SNSCs. Results show that tandem design leads to much higher light-conversion capability than μc-Si:H S-SNSCs, but exhibits superior performance than a-Si:H S-SNSCs only for cells with large radii.

  17. GaAs, AlGaAs and InGaP Tunnel Junctions for Multi-Junction Solar Cells Under Concentration: Resistance Study

    SciTech Connect

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin; Masson, Denis; Riel, Bruno; Fafard, Simon; Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent

    2010-10-14

    The following four TJ designs, AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs are studied to determine minimum doping concentration to achieve a resistance of <10{sup -4} {omega}{center_dot}cm{sup 2} and a peak tunneling current suitable for MJ solar cells up to 1500-suns concentration (operating current of 21 A/cm{sup 2}). Experimentally calibrated numerical models are used to determine how the resistance changes as a function of doping concentration. The AlGaAs/GaAs TJ design is determined to require the least doping concentration to achieve the specified resistance and peak tunneling current, followed by the GaAs/GaAs, and AlGaAs/AlGaAs TJ designs. The AlGaAs/InGaP TJ design can only achieve resistances >5x10{sup -4} {omega}cm{sup 2}.

  18. Internal luminescence efficiencies in InGaP/GaAs/Ge triple-junction solar cells evaluated from photoluminescence through optical coupling between subcells.

    PubMed

    Tex, David M; Imaizumi, Mitsuru; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-12-08

    In-situ characterization is one of the most powerful techniques to improve material quality and device performance. Especially in view of highly efficient tandem solar cells this is an important issue for improving the cost-performance ratio. Optical techniques are suitable characterization methods, since they are non-destructing and contactless. In this work, we measured the power dependence of photoluminescence (PL) from the InGaP and GaAs subcells of an industry-standard triple-junction solar cell. High luminescence yields enhance the luminescence coupling, which was directly verified by time-resolved PL measurements. We present a new method to determine the internal luminescence efficiencies of InGaP and GaAs subcells with the aid of luminescence coupling. High luminescence efficiencies of 90% for GaAs and more than 20% for InGaP were found, which suggest that the material quality of the grown GaAs layer is excellent while the intrinsic luminescence limit of InGaP is still not reached even for high excitation conditions. The PL method is useful for probing the intrinsic material properties of the subcells in flat band condition, without influence of transport. Since no calibration of absolute PL is required, a fast screening of the material quality is possible, which should be extremely helpful for the solar cell industry.

  19. Internal luminescence efficiencies in InGaP/GaAs/Ge triple-junction solar cells evaluated from photoluminescence through optical coupling between subcells

    PubMed Central

    Tex, David M.; Imaizumi, Mitsuru; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-01-01

    In-situ characterization is one of the most powerful techniques to improve material quality and device performance. Especially in view of highly efficient tandem solar cells this is an important issue for improving the cost-performance ratio. Optical techniques are suitable characterization methods, since they are non-destructing and contactless. In this work, we measured the power dependence of photoluminescence (PL) from the InGaP and GaAs subcells of an industry-standard triple-junction solar cell. High luminescence yields enhance the luminescence coupling, which was directly verified by time-resolved PL measurements. We present a new method to determine the internal luminescence efficiencies of InGaP and GaAs subcells with the aid of luminescence coupling. High luminescence efficiencies of 90% for GaAs and more than 20% for InGaP were found, which suggest that the material quality of the grown GaAs layer is excellent while the intrinsic luminescence limit of InGaP is still not reached even for high excitation conditions. The PL method is useful for probing the intrinsic material properties of the subcells in flat band condition, without influence of transport. Since no calibration of absolute PL is required, a fast screening of the material quality is possible, which should be extremely helpful for the solar cell industry. PMID:27929037

  20. Internal luminescence efficiencies in InGaP/GaAs/Ge triple-junction solar cells evaluated from photoluminescence through optical coupling between subcells

    NASA Astrophysics Data System (ADS)

    Tex, David M.; Imaizumi, Mitsuru; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-12-01

    In-situ characterization is one of the most powerful techniques to improve material quality and device performance. Especially in view of highly efficient tandem solar cells this is an important issue for improving the cost-performance ratio. Optical techniques are suitable characterization methods, since they are non-destructing and contactless. In this work, we measured the power dependence of photoluminescence (PL) from the InGaP and GaAs subcells of an industry-standard triple-junction solar cell. High luminescence yields enhance the luminescence coupling, which was directly verified by time-resolved PL measurements. We present a new method to determine the internal luminescence efficiencies of InGaP and GaAs subcells with the aid of luminescence coupling. High luminescence efficiencies of 90% for GaAs and more than 20% for InGaP were found, which suggest that the material quality of the grown GaAs layer is excellent while the intrinsic luminescence limit of InGaP is still not reached even for high excitation conditions. The PL method is useful for probing the intrinsic material properties of the subcells in flat band condition, without influence of transport. Since no calibration of absolute PL is required, a fast screening of the material quality is possible, which should be extremely helpful for the solar cell industry.

  1. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    SciTech Connect

    Masuda, T; Tomasulo, S; Lang, JR; Lee, ML

    2015-03-07

    We have investigated similar to 2.0 eV (AlxGa1-x)(0.51)In0.49P and similar to 1.9 eV Ga0.51In0.49P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (AlxGa1-x)(0.51)In0.49P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (V-oc) ranging from 1.29 to 1.30 V for Ga0.51In0.49P cells, and 1.35-1.37 V for (AlxGa1-x)(0.51)In0.49P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (W-oc = E-g/q - V-oc) of Ga0.51In0.49P cells to decrease from similar to 575 mV to similar to 565 mV, while that of (AlxGa1-x)(0.51)In0.49P cells remained nearly constant at 620 mV. The constant Woc as a function of substrate offcut for (AlxGa1-x)(0.51)In0.49P implies greater losses from non-radiative recombination compared with the Ga0.51In0.49P devices. In addition to larger Woc values, the (AlxGa1-x)(0.51)In0.49P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga0.51In0.49P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (AlxGa1-x)(0.51)In0.49P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells. (C) 2015 AIP Publishing LLC.

  2. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Masuda, Taizo; Tomasulo, Stephanie; Lang, Jordan R.; Lee, Minjoo Larry

    2015-03-01

    We have investigated ˜2.0 eV (AlxGa1-x)0.51In0.49P and ˜1.9 eV Ga0.51In0.49P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (AlxGa1-x)0.51In0.49P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (Voc) ranging from 1.29 to 1.30 V for Ga0.51In0.49P cells, and 1.35-1.37 V for (AlxGa1-x)0.51In0.49P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (Woc = Eg/q - Voc) of Ga0.51In0.49P cells to decrease from ˜575 mV to ˜565 mV, while that of (AlxGa1-x)0.51In0.49P cells remained nearly constant at 620 mV. The constant Woc as a function of substrate offcut for (AlxGa1-x)0.51In0.49P implies greater losses from non-radiative recombination compared with the Ga0.51In0.49P devices. In addition to larger Woc values, the (AlxGa1-x)0.51In0.49P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga0.51In0.49P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (AlxGa1-x)0.51In0.49P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells.

  3. Four-Junction Solar Cell with 40% Target Efficiency Fabricated by Wafer Bonding and Layer Transfer: Final Technical Report, 1 January 2005 - 31 December 2007

    SciTech Connect

    Atwater, H. A.

    2008-11-01

    We realized high-quality InGaP/GaAs 2-junction top cells on Ge/Si, InGaAs/InP bottom cells, direct-bond series interconnection of tandem cells, and modeling of bonded 3- and 4-junction device performance.

  4. Use of a ZnTe:N/ZnO: A1 bilayer in thin-flim, multi-junction II-VI solar cells.

    NASA Astrophysics Data System (ADS)

    Rich, Geoffrey

    2002-03-01

    Development of a low-cost, thin-film tandem solar cell structure utilizing II-VI compound semiconductors is described. The structure consists of a CdS/CdTe top cell to which a bilayer of ZnTe:N/ZnO:Al is applied, subsequently bonded to a thin-film or crystalline bottom cell. The bilayer forms a back contact to the top cell, with an appropriate optical transmission and lateral conductivity characteristic for use in a four-terminal tandem device. Previous work at the University of Toledo has shown that ZnTe can be effectively doped by reactive sputtering in nitrogen, and demonstration of ZnTe:N as a component of a back contact to CdS/CdTe heterojunctions has been demonstrated [1]. The addition of a ZnO:Al layer provides the necessary lateral conductivity required by a four-terminal tandem solar cell design. Test structures consisting of Al/ZnTe:N/ZnO:Al/Al, deposited on glass by magnetron sputtering, are characterized optically and electrically. The ZnTe:N/ZnO:Al bilayer is applied to thin-film CdS/CdTe heterojunctions deposited by rapid, low-cost techniques (provided by First Solar, LLC). With the addition of a metallic grid, functioning top cell structures are created and measured. By bonding a bottom cell to this structure, a complete dual-junction, four-terminal device is constructed and demonstrated. [1] J. Drayton, A. Gupta, K. Makhratchev, K. Price, R. Bohn, and A. Compaan, Mat. Res. Soc. Symp. Proc. 668, “II-VI Compound Semiconductor Photovoltaic Materials,” ed. by R Noufi, R. W. Birkmire, D. Lincot, H. W. Schock.

  5. Investigation of Junction Properties of CdS/CdTe Solar Cells and their Correlation to Device Properties (Presentation)

    SciTech Connect

    Dhere, R. G.; Zhang, Y.; Romero, M. J.; Asher, S. E.; Young, M.; To, B.; Noufi, R.; Gessert, T. A.

    2008-05-01

    The objective of the Junction Studies are: (1) understand the nature of the junction in the CdTe/CdS device; (2) correlate the device fabrication parameters to the junction formation; and (3) develop a self consistent device model to explain the device properties. Detailed analysis of CdS/CdTe and SnO{sub 2}/CdTe devices prepared using CSS CdTe is discussed.

  6. Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe-ZnO Tunnel Junction.

    PubMed

    Crisp, Ryan W; Pach, Gregory F; Kurley, J Matthew; France, Ryan M; Reese, Matthew O; Nanayakkara, Sanjini U; MacLeod, Bradley A; Talapin, Dmitri V; Beard, Matthew C; Luther, Joseph M

    2017-02-08

    We developed a monolithic CdTe-PbS tandem solar cell architecture in which both the CdTe and PbS absorber layers are solution-processed from nanocrystal inks. Due to their tunable nature, PbS quantum dots (QDs), with a controllable band gap between 0.4 and ∼1.6 eV, are a promising candidate for a bottom absorber layer in tandem photovoltaics. In the detailed balance limit, the ideal configuration of a CdTe (Eg = 1.5 eV)-PbS tandem structure assumes infinite thickness of the absorber layers and requires the PbS band gap to be 0.75 eV to theoretically achieve a power conversion efficiency (PCE) of 45%. However, modeling shows that by allowing the thickness of the CdTe layer to vary, a tandem with efficiency over 40% is achievable using bottom cell band gaps ranging from 0.68 and 1.16 eV. In a first step toward developing this technology, we explore CdTe-PbS tandem devices by developing a ZnTe-ZnO tunnel junction, which appropriately combines the two subcells in series. We examine the basic characteristics of the solar cells as a function of layer thickness and bottom-cell band gap and demonstrate open-circuit voltages in excess of 1.1 V with matched short circuit current density of 10 mA/cm(2) in prototype devices.

  7. Theoretical modeling and optimization of III-V GaInP/GaAs/Ge monolithic triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Leem, Jung Woo; Yu, Jae Su; Kim, Jong Nam; Noh, Sam Kyu

    2014-05-01

    We design and optimize monolithic III-V GaInP/GaAs/Ge triple-junction (TJ) solar cells by using a commercial software Silvaco ATLAS simulator to obtain the maximum short-circuit current density J sc . The maximum J sc , which is a current matching value between the GaInP top and GaAs middle subcells, can be determined by varying the base thicknesses of the GaInP top and GaAs middle subcells. From the numerical simulation results, a matched maximum J sc value of 13.92 mA/cm2 is obtained at base thicknesses of 0.57 μm and 3 μm for the GaInP top and GaAs middle subcells, respectively, under 1-sun air mass 1.5 global spectrum illumination, leading to a high power conversion efficiency of 30.72%. The open-circuit voltage and the fill factor are 2.55 V and 86.55%, respectively. For the optimized cell structure, the external quantum efficiency and the photogeneration rate distributions are also investigated. To obtain efficient antireflection coatings (ARCs), we perform optical reflectance calculations by using a rigorous coupled-wave analysis method. For this, a silicon oxide/titanium oxide double-layer is used as an ARC on the TJ solar cell.

  8. Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

    NASA Astrophysics Data System (ADS)

    Kewei, Cao; Tong, Liu; Jingming, Liu; Hui, Xie; Dongyan, Tao; Youwen, Zhao; Zhiyuan, Dong; Feng, Hui

    2016-06-01

    Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B2O3 encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters. Project supported by the National Natural Science Foundation of China (No. 61474104).

  9. Room-temperature wafer bonded InGaP/GaAs//InGaAsP/InGaAs four-junction solar cell grown by all-solid state molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Dai, Pan; Lu, Shulong; Uchida, Shiro; Ji, Lian; Wu, Yuanyuan; Tan, Ming; Bian, Lifeng; Yang, Hui

    2016-01-01

    An InGaP/GaAs tandem cell on a GaAs substrate and an InGaAsP/InGaAs tandem cell on an InP substrate were grown separately by all-solid-state molecular beam epitaxy. A room-temperature direct wafer-bonding technique was used to integrate these subcells into an InGaP/GaAs//InGaAsP/InGaAs wafer-bonded solar cell, which resulted in an abrupt interface with low resistance and high optical transmission. The current-matching design for the base layer thickness of each cell was investigated. The resulting efficiency of the four-junction solar cell was 42.0% at 230 suns, which demonstrates the great potential of the room-temperature wafer-bonding technique to achieve high conversion efficiency for cells with four or more junctions.

  10. InGaP/GaAs Inverted Dual Junction Solar Cells For CPV Applications Using Metal-Backed Epitaxial Lift-Off

    SciTech Connect

    Bauhuis, Gerard J.; Mulder, Peter; Haverkamp, Erik J.; Schermer, John J.; Nash, Lee J.; Fulgoni, Dominic J. F.; Ballard, Ian M.; Duggan, Geoffrey

    2010-10-14

    The epitaxial lift-off (ELO) technique has been combined with inverted III-V PV cell epitaxial growth with the aim of employing thin film PV cells in HCPV systems. In a stepwise approach to the realization of an inverted triple junction on a MELO platform we have first grown a GaAs single junction PV cell to establish the basic layer release process and cell processing steps followed by the growth, fabrication and test of an inverted InGaP/GaAs dual junction structure.

  11. Cadmium-free junction fabrication process for CuInSe{sub 2} thin film solar cells

    SciTech Connect

    Ramanathan, K.V.; Contreras, M.A.; Bhattacharya, R.N.; Keane, J.; Noufi, R.

    1999-09-07

    The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

  12. Cadmium-free junction fabrication process for CuInSe.sub.2 thin film solar cells

    DOEpatents

    Ramanathan, Kannan V.; Contreras, Miguel A.; Bhattacharya, Raghu N.; Keane, James; Noufi, Rommel

    1999-01-01

    The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

  13. Non-destructive, ultra-low resistance, thermally stable contacts for use on shallow junction InP solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Fatemi, N. S.; Korenyi-Both, A. L.

    1993-01-01

    Contact formation to InP is plagued by violent metal-semiconductor intermixing that takes place during the contact sintering process. Because of this the InP solar cell cannot be sintered after contact deposition. This results in cell contact resistances that are orders of magnitude higher than those that could be achieved if sintering could be performed in a non-destructive manner. We report here on a truly unique contact system involving Au and Ge, which is easily fabricated, which exhibits extremely low values of contact resistivity, and in which there is virtually no metal-semiconductor interdiffusion, even after extended sintering. We present a description of this contact system and suggest possible mechanisms to explain the observed behavior.

  14. Superstrate sub-cell voltage-matched multijunction solar cells

    SciTech Connect

    Mascarenhas, Angelo; Alberi, Kirstin

    2016-03-15

    Voltage-matched thin film multijunction solar cell and methods of producing cells having upper CdTe pn junction layers formed on a transparent substrate which in the completed device is operatively positioned in a superstate configuration. The solar cell also includes a lower pn junction formed independently of the CdTe pn junction and an insulating layer between CdTe and lower pn junctions. The voltage-matched thin film multijunction solar cells further include a parallel connection between the CdTe pn junction and lower pn junctions to form a two-terminal photonic device. Methods of fabricating devices from independently produced upper CdTe junction layers and lower junction layers are also disclosed.

  15. Thin, Lightweight Solar Cell

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.; Weinberg, Irving

    1991-01-01

    Improved design for thin, lightweight solar photovoltaic cells with front contacts reduces degradation of electrical output under exposure to energetic charged particles (protons and electrons). Increases ability of cells to maintain structural integrity under exposure to ultraviolet radiation by eliminating ultraviolet-degradable adhesives used to retain cover glasses. Interdigitated front contacts and front junctions formed on semiconductor substrate. Mating contacts formed on back surface of cover glass. Cover glass and substrate electrostatically bonded together.

  16. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    SciTech Connect

    Masuda, Taizo Tomasulo, Stephanie; Lang, Jordan R.; Lee, Minjoo Larry

    2015-03-07

    We have investigated ∼2.0 eV (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P and ∼1.9 eV Ga{sub 0.51}In{sub 0.49}P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (V{sub oc}) ranging from 1.29 to 1.30 V for Ga{sub 0.51}In{sub 0.49}P cells, and 1.35–1.37 V for (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (W{sub oc} = E{sub g}/q − V{sub oc}) of Ga{sub 0.51}In{sub 0.49}P cells to decrease from ∼575 mV to ∼565 mV, while that of (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells remained nearly constant at 620 mV. The constant W{sub oc} as a function of substrate offcut for (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P implies greater losses from non-radiative recombination compared with the Ga{sub 0.51}In{sub 0.49}P devices. In addition to larger W{sub oc} values, the (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga{sub 0.51}In{sub 0.49}P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells.

  17. Locating the electrical junctions in Cu(In,Ga)Se 2 and Cu 2 ZnSnSe 4 solar cells by scanning capacitance spectroscopy: Locating the electrical junctions in Cu(In,Ga)Se 2 and Cu 2 ZnSnSe 4 solar cells

    SciTech Connect

    Xiao, Chuanxiao; Jiang, Chun-Sheng; Moutinho, Helio; Levi, Dean; Yan, Yanfa; Gorman, Brian; Al-Jassim, Mowafak

    2016-08-09

    We determined the electrical junction (EJ) locations in Cu(In,Ga)Se2 (CIGS) and Cu2ZnSnSe4 (CZTS) solar cells with ~20-nm accuracy by developing scanning capacitance spectroscopy (SCS) applicable to the thin-film devices. Cross-sectional sample preparation for the SCS measurement was developed by high-energy ion milling at room temperature for polishing the cross section to make it flat, followed by low-energy ion milling at liquid nitrogen temperature for removing the damaged layer and subsequent annealing for growing a native oxide layer. The SCS shows distinct p-type, transitional, and n-type spectra across the devices, and the spectral features change rapidly with location in the depletion region, which results in determining the EJ with ~20-nm resolution. We found an n-type CIGS in the region next to the CIGS/CdS interface; thus, the cell is a homojunction. The EJ is ~40 nm from the interface on the CIGS side. In contrast, such an n-type CZTS was not found in the CZTS/CdS cells. The EJ is ~20 nm from the CZTS/CdS interface, which is consistent with asymmetrical carrier concentrations of the p-CZTS and n-CdS in a heterojunction cell. Our results of unambiguously determination of the junction locations contribute significantly to understanding the large open-circuit voltage difference between CIGS and CZTS.

  18. Carrier dynamics in QW and bulk bismide and epitaxial lift off GaAs-In(Al)GaP double heterostructures grown by MOVPE for multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Peterson, Mark; Lingley, Zachary; LaLumondiere, Stephen; Moss, Steven C.; Kim, Honghyuk; Forghani, Kamran; Guan, Yingxin; Kim, Kangho; Lee, Jaejin; Mawst, Luke J.; Kuech, Thomas F.; Tatavarti, Rao

    2016-03-01

    III-V multi-junction solar cells are based on a triple-junction design that consists of an InGaP top junction, a GaAs middle junction, and a bottom junction that employs either a 1eV material grown on the GaAs substrate or InGaAs grown on the Ge substrate. The most promising 1 eV materials under extensive investigation are the bulk dilute nitride such as InGaAsN(Sb) lattice-matched to GaAs substrate and the dilute-bismide quantum well materials, such as GaAsBi, strain-compensated with GaAsP barriers. Both approaches have the potential to achieve high performance triple-junction solar cells. In addition, space satellite applications utilizing III-V triple-junction solar cells can have significantly reduced weight and high efficiency. An attractive approach to achieve these goals is to employ full-wafer epitaxial lift off (ELO) technology, which can eliminate the substrate weight and also enable multiple substrate re-usages. For the present study, we employed time-resolved photoluminescence (TR-PL) techniques to study carrier dynamics in MOVPE-grown bulk dilute bismide double heterostructures (DH). Carrier lifetime measurements are crucial to optimizing MOVPE materials growth. We have studied carrier dynamics in GaAsBi QW structures with GaAsP barriers. Carrier lifetimes were measured from GaAsBi DH samples at different stages of post-growth thermal annealing steps. Post-growth annealing yielded significant improvements in carrier lifetimes. Based on this study, single junction solar cells (SJSC) were grown and annealed under a variety of conditions and characterized. The SJSC annealed at 600 - 650 °C exhibited improved response in EQE spectra. In addition, we studied carrier dynamics in MOVPE-grown GaAs-In(Al)GaP DH samples grown on GaAs substrates. The structures were grown on top of a thin AlAs release layer, which allowed epitaxial layers grown on top of the AlAs layer to be removed from the substrate. The GaAs active layers had various doping densities and

  19. Theory of back-surface-field solar cells

    NASA Technical Reports Server (NTRS)

    Vonroos, O.

    1979-01-01

    Report describes simple concise theory of back-surface-field (BSF) solar cells (npp + junctions) based on Shockley's depletion-layer approximation and cites superiority of two-junction devices over conventional unijunction cells.

  20. InP/Ga0.47In0.53As monolithic, two-junction, three-terminal tandem solar cells

    NASA Technical Reports Server (NTRS)

    Wanlaas, M. W.; Gessert, T. A.; Horner, G. S.; Emery, K. A.; Coutts, T. J.

    1991-01-01

    The work presented has focussed on increasing the efficiency of InP-based solar cells through the development of a high-performance InP/Ga(0.47)In(0.53)As two-junction, three-terminal monolithic tandem cell. Such a tandem is particularly suited to space applications where a radiation-hard top cell (i.e., InP) is required. Furthermore, the InP/Ga(0.47)In(0.53)As materials system is lattice matched and offers a top cell/bottom cell bandgap differential (0.60 eV at 300 K) suitable for high tandem cell efficiencies under AMO illumination. A three-terminal configuration was chosen since it allows for independent power collection from each subcell in the monolithic stack, thus minimizing the adverse impact of radiation damage on the overall tandem efficiency. Realistic computer modeling calculations predict an efficiency boost of 7 to 11 percent from the Ga(0.47)In(0.53)As bottom cell under AMO illumination (25 C) for concentration ratios in the 1 to 1000 range. Thus, practical AMO efficiencies of 25 to 32 percent appear possible with the InP/Ga(0.47)In(0.53)As tandem cell. Prototype n/p/n InP/Ga(0.47)In(0.53)As monolithic tandem cells were fabricated and tested successfully. Using an aperture to define the illuminated areas, efficiency measurements performed on a non-optimized device under standard global illumination conditions (25 C) with no antireflection coating (ARC) give 12.2 percent for the InP top cell and 3.2 percent for the Ga(0.47)In(0.53)As bottom cell, yielding an overall tandem efficiency of 15.4 percent. With an ARC, the tandem efficiency could reach approximately 22 percent global and approximately 20 percent AMO. Additional details regarding the performance of individual InP and Ga(0.47)In(0.53)As component cells, fabrication and operation of complete tandem cells and methods for improving the tandem cell performance, are also discussed.

  1. Solar Cells

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Heat Exchanger Method (HEM) produces high efficiency crystal ingots in an automated well-insulated furnace offering low equipment, labor and energy costs. The "grown" silicon crystals are used to make solar cells, or photovoltaic cells which convert sunlight directly into electricity. The HEM method is used by Crystal Systems, Inc. and was developed under a NASA/Jet Propulsion Laboratory contract. The square wafers which are the result of the process are sold to companies manufacturing solar panels.

  2. Measured and Simulated Dark J-V Characteristics of a-Si:H Single Junction p-i-n Solar Cells Irradiated with 40 keV Electrons

    NASA Technical Reports Server (NTRS)

    Lord, Kenneth; Woodyard, James R.

    2002-01-01

    The effect of 40 keV electron irradiation on a-Si:H p-i-n single-junction solar cells was investigated using measured and simulated dark J-V characteristics. EPRI-AMPS and PC-1D simulators were explored for use in the studies. The EPRI-AMPS simulator was employed and simulator parameters selected to produce agreement with measured J-V characteristics. Three current mechanisms were evident in the measured dark J-V characteristics after electron irradiation, namely, injection, shunting and a term of the form CV(sup m). Using a single discrete defect state level at the center of the band gap, good agreement was achieved between measured and simulated J-V characteristics in the forward-bias voltage region where the dark current density was dominated by injection. The current mechanism of the form CV(sup m) was removed by annealing for two hours at 140 C. Subsequent irradiation restored the CV(sup m) current mechanism and it was removed by a second anneal. Some evidence of the CV(sup m) term is present in device simulations with a higher level of discrete density of states located at the center of the bandgap.

  3. Stability and controllability of InGaAs/GaAsP wire-on-well (WoW) structure for multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Cho, Hirofumi; Toprasertpong, Kasidit; Sodabanlu, Hassanet; Watanabe, Kentaroh; Sugiyama, Masakazu; Nakano, Yoshiaki

    2017-04-01

    Wire on Well (WoW) structure embedded in a matrix is naturally formed by growing InxGa1-xAs/GaAs1-yPy strained multiple quantum wells (MQW) on vicinal substrates and employing triethylgallium (TEGa) as a precursor in low-temperature MOVPE. The structure is useful for the subcell in current-matched mult-junction solar cells with lattice-matched materials because of its ability of band-gap tuning. In this research, high density and uniform In0.30Ga0.70As/GaAs0.6P0.4 WoW was obtained up to 200 stacks and its structure was analyzed by X-ray diffraction reciprocal space mapping, atomic force microscopy and scanning transmission electron microscopy. The structure of the wire can be controlled by changing the equivalent layer thicknesses of In0.30Ga0.70As and GaAs0.6P0.4. The photoluminescence peak from the WoW shifted according to the size of InGaAs wires and the intensity was dependent on the accumulation of lattice-mismatch stress.

  4. Report on Project to Characterize Multi-Junction Solar Cells in the Stratosphere using Low-Cost Balloon and Communication Technologies

    NASA Technical Reports Server (NTRS)

    Mirza, Ali; Sant, David; Woodyard, James R.; Johnston, Richard R.; Brown, William J.

    2002-01-01

    Balloon, control and communication technologies are under development in our laboratory for testing multi-junction solar cells in the stratosphere to achieve near AM0 conditions. One flight, Suntracker I, has been carried out reported earlier. We report on our efforts in preparation for a second flight, Suntracker II, that was aborted due to hardware problems. The package for Suntracker I system has been modified to include separate electronics and battery packs for the 70 centimeter and 2 meter systems. The collimator control system and motor gearboxes have been redesigned to address problems with the virtual stops and backlash. Surface mount technology on a printed circuit board was used in place of the through-hole prototype circuit in efforts to reduce weight and size, and improve reliability. A mobile base station has been constructed that includes a 35' tower with a two axis rotator and multi-element yagi antennas. Modifications in Suntracker I and the factors that lead to aborting Suntracker II are discussed.

  5. Effect of random p-n junctions on quasi-solid-state dye-sensitized solar cells with polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Cui, Jiarui; Yang, Ying; Yi, Pengfei; Guo, Xueyi

    2014-12-01

    In this paper, the effect of p-n junction additives via blending p-type semiconductors (NiO and CuI) with n-type TiO2 in polymer electrolyte on quasi-solid-state DSSCs is studied. The conduction mechanism of DSSCs modified with random p-n junctions has been investigated by FTIR, SEM, UV-Vis and electrochemical analysis. The results indicate that the CuI-TiO2 p-n blend modified polymer electrolyte reaches the maximum ionic conductivity of 6.44 mS cm-1, which is almost twice over than that of pure-TiO2 modified one. From photovoltaic study, it is found that introducing CuI-TiO2 and NiO-TiO2 p-n blends in polymer electrolyte can obviously improve electron recombination and light-to-electric conversion efficiency of DSSCs. The conversion efficiency of CuI-TiO2 p-n blend modified DSSC is 3.34%, which is much higher than that of pure TiO2 modified device (1.76%). It is also demonstrated that the photovoltaic properties of DSSCs directly depends on the ratio of p-type CuI and n-type TiO2 in the p-n blends and the optimal conversion efficiency of 4.27% is obtained at CuI:TiO2 ratio of 4:1.

  6. High temperature annealing of minority carrier traps in irradiated MOCVD n(+)p InP solar cell junctions

    NASA Technical Reports Server (NTRS)

    Messenger, S. R.; Walters, R. J.; Summers, G. P.

    1993-01-01

    Deep level transient spectroscopy was used to monitor thermal annealing of trapping centers in electron irradiated n(+)p InP junctions grown by metalorganic chemical vapor deposition, at temperatures ranging from 500 up to 650K. Special emphasis is given to the behavior of the minority carrier (electron) traps EA (0.24 eV), EC (0.12 eV), and ED (0.31 eV) which have received considerably less attention than the majority carrier (hole) traps H3, H4, and H5, although this work does extend the annealing behavior of the hole traps to higher temperatures than previously reported. It is found that H5 begins to anneal above 500K and is completely removed by 630K. The electron traps begin to anneal above 540K and are reduced to about half intensity by 630K. Although they each have slightly different annealing temperatures, EA, EC, and ED are all removed by 650K. A new hole trap called H3'(0.33 eV) grows as the other traps anneal and is the only trap remaining at 650K. This annealing behavior is much different than that reported for diffused junctions.

  7. InGaP/GaAs Dual-Junction Solar Cell with AlGaAs/GaAs Tunnel Diode Grown on 10° off Misoriented GaAs Substrate

    NASA Astrophysics Data System (ADS)

    Yu, Hung Wei; Chung, Chen Chen; Te Wang, Chin; Nguyen, Hong Quan; Tinh Tran, Binh; Lin, Kung Liang; Dee, Chang Fu; Yeop Majlis, Burhanuddin; Chang, Edward Yi

    2012-08-01

    InGaP/GaAs dual-junction solar cells with different tunnel diodes (TDs) grown on misoriented GaAs substrates are investigated. It is demonstrated that the solar cells with P++-AlGaAs/N++-GaAs TDs grown on 10° off GaAs substrates not only show a higher external quantum efficiency (EQE) but also generate a higher peak current density (Jpeak) at higher concentration ratios (185×) than the solar cells with P++-GaAs/N++-InGaP TDs grown on 6° off GaAs substrates. Furthermore, the cell design with P++-AlGaAs/N++-GaAs TDs grown on 10° off GaAs substrates does not generate a disordered InGaP epitaxial layer during material growth, and thus shows superior current-voltage characteristics.

  8. Cadmium sulfide solar cells

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.

    1975-01-01

    Development, fabrication and applications of CdS solar cells are reviewed in detail. The suitability of CdS cells for large solar panels and microcircuitry, and their low cost, are emphasized. Developments are reviewed by manufacturer-developer. Vapor phase deposition of thin-film solar cells, doping and co-evaporation, sputtering, chemical spray, and sintered layers are reviewed, in addition to spray deposition, monograin layer structures, and silk screening. Formation of junctions by electroplating, evaporation, brushing, CuCl dip, and chemiplating are discussed, along with counterelectrode fabrication, VPD film structures, the Cu2S barrier layer, and various photovoltaic effects (contact photovoltage, light intensity variation, optical enhancement), and various other CdS topics.

  9. Module level solutions to solar cell polarization

    DOEpatents

    Xavier, Grace , Li; Bo, [San Jose, CA

    2012-05-29

    A solar cell module includes interconnected solar cells, a transparent cover over the front sides of the solar cells, and a backsheet on the backsides of the solar cells. The solar cell module includes an electrical insulator between the transparent cover and the front sides of the solar cells. An encapsulant protectively packages the solar cells. To prevent polarization, the insulator has resistance suitable to prevent charge from leaking from the front sides of the solar cells to other portions of the solar cell module by way of the transparent cover. The insulator may be attached (e.g., by coating) directly on an underside of the transparent cover or be a separate layer formed between layers of the encapsulant. The solar cells may be back junction solar cells.

  10. Cadmium sulphide solar cell

    SciTech Connect

    Bassett, P.J.; Verheijen, A.W.

    1984-07-31

    The invention relates to the manufacture of cadmium sulphide solar cells. A cell is formed of a glass substrate 10, a front contact 12 made, for example, of tin oxide, a cadmium sulphide layer 14 and a copper sulphide layer 16, the junction between the layers 14 and 16 is photovoltaic. In order to form a rear contact 18 on the copper sulphide layer, the invention proposes vapor depositing a mixed layer of copper and copper oxide onto the sulphide layer. The invention also describes a method of heat treatment following the formation of the rear contact in order to optimise the electrical performance of the cell.

  11. Solar cell circuit and method for manufacturing solar cells

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick (Inventor)

    2010-01-01

    The invention is a novel manufacturing method for making multi-junction solar cell circuits that addresses current problems associated with such circuits by allowing the formation of integral diodes in the cells and allows for a large number of circuits to readily be placed on a single silicon wafer substrate. The standard Ge wafer used as the base for multi-junction solar cells is replaced with a thinner layer of Ge or a II-V semiconductor material on a silicon/silicon dioxide substrate. This allows high-voltage cells with multiple multi-junction circuits to be manufactured on a single wafer, resulting in less array assembly mass and simplified power management.

  12. Fabrication of high-efficiency n(+)-p junction InP solar cells by using group VIb element diffusion into p-type InP

    NASA Astrophysics Data System (ADS)

    Yamamoto, A.; Yamaguchi, M.; Uemura, C.

    1985-12-01

    The fabrication of n(+)-p homojunction InP solar cells has been studied using thermal diffusion of S, Se, or Te into p-type InP substrates. Sulphur diffusion using an In2S3 source was found to be effective in forming a shallow and steep n(+)-p function without surface morphology degradation of substrates. A conversion efficiency (active area) of 18 percent, which is the highest efficiency ever reported for InP homojunction solar cells, was obtained by optimizing fabrication conditions for sulphur-diffused cells. An electron irradiation study on fabricated cells has also been made. The InP solar cell was found to have a higher resistance to radiation degradation than Si and GaAs cells. Through these studies, it has been demonstrated that the InP solar cell has excellent potential for space applications.

  13. High efficiency solar cell research for space applications

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1985-01-01

    A review is given of NASA photovoltaic research with emphasis on the activities of the Lewis Research Center. High efficiency solar cell research is discussed, as well as solar arrays, multi-junction cell bandgaps, and plasmon coupling.

  14. Producing Solar Cells By Surface Preparation For Accelerated Nucleation Of Microcrystalline Silicon On Heterogeneous Substrates.

    DOEpatents

    Yang, Liyou; Chen, Liangfan

    1998-03-24

    Attractive multi-junction solar cells and single junction solar cells with excellent conversion efficiency can be produced with a microcrystalline tunnel junction, microcrystalline recombination junction or one or more microcrystalline doped layers by special plasma deposition processes which includes plasma etching with only hydrogen or other specified etchants to enhance microcrystalline growth followed by microcrystalline. nucleation with a doped hydrogen-diluted feedstock.

  15. Tight Junction Proteins in Human Schwann Cell Autotypic Junctions

    PubMed Central

    Alanne, Maria H.; Pummi, Kati; Heape, Anthony M.; Grènman, Reidar; Peltonen, Juha; Peltonen, Sirkku

    2009-01-01

    Tight junctions (TJs) form physical barriers in various tissues and regulate paracellular transport of ions, water, and molecules. Myelinating Schwann cells form highly organized structures, including compact myelin, nodes of Ranvier, paranodal regions, Schmidt-Lanterman incisures, periaxonal cytoplasmic collars, and mesaxons. Autotypic TJs are formed in non-compacted myelin compartments between adjacent membrane lamellae of the same Schwann cell. Using indirect immunofluorescence and RT-PCR, we analyzed the expression of adherens junction (E-cadherin) and TJ [claudins, zonula occludens (ZO)-1, occludin] components in human peripheral nerve endoneurium, showing clear differences with published rodent profiles. Adult nerve paranodal regions contained E-cadherin, claudin-1, claudin-2, and ZO-1. Schmidt-Lanterman incisures contained E-cadherin, claudin-1, claudin-2, claudin-3, claudin-5, ZO-1, and occludin. Mesaxons contained E-cadherin, claudin-1, claudin-2, claudin-3, ZO-1, and occludin. None of the proteins studied were associated with nodal inter-Schwann cell junctions. Fetal nerve expression of claudin-1, claudin-3, ZO-1, and occludin was predominantly punctate, with a mesaxonal labeling pattern, but paranodal (ZO-1, claudin-3) and Schmidt-Lanterman incisure (claudins-1 and -3) expression profiles typical of compact myelin were visible by gestational week 37. The clear differences observed between human and published rodent nerve profiles emphasize the importance of human studies when translating the results of animal models to human diseases. (J Histochem Cytochem 57:523–529, 2009) PMID:19153196

  16. An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell

    SciTech Connect

    Venkatasubramanian, R. )

    1993-01-01

    This report describes work to develop inverted-grown Al[sub 0.34]Ga[sub 0.66]As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al[sub 0.34]Ga[sub 0.66]As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The cycled'' organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al[sub 0.34]Ga[sub 0.66]As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.

  17. Energy level alignment in polymer organic solar cells at donor-acceptor planar junction formed by electrospray vacuum deposition

    SciTech Connect

    Kim, Ji-Hoon; Hong, Jong-Am; Kwon, Dae-Gyeon; Seo, Jaewon; Park, Yongsup

    2014-04-21

    Using ultraviolet photoelectron spectroscopy (UPS), we have measured the energy level offset at the planar interface between poly(3-hexylthiophene) (P3HT) and C{sub 61}-butyric acid methylester (PCBM). Gradual deposition of PCBM onto spin-coated P3HT in high vacuum was made possible by using electrospray vacuum deposition (EVD). The UPS measurement of EVD-prepared planar interface resulted in the energy level offset of 0.91 eV between P3HT HOMO and PCBM LUMO, which is considered as the upper limit of V{sub oc} of the organic photovoltaic cells.

  18. Progress in a-SiOx:H thin film solar cells with patterned MgF2 dielectric for top cell of multi-junction system

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Won; Sichanugrist, Porponth; Konagai, Makoto

    2016-07-01

    We successfully designed and experimentally demonstrated an application of patterned MgF2 dielectric material at rear Al-doped ZnO (AZO)/Ag interface in thin film amorphous silicon oxide ( a-SiOx:H) solar cells. When it was realized in practical device process, MgF2 coverage with patterned morphology was employed to allow for current flow between the AZO and Ag against highly resistive MgF2 material. On the basis of the suggested structure, we found an improvement in quantum efficiency of the solar cells with the patterned MgF2. In addition, an enhancement of open circuit voltage ( V oc ) and fill factor ( FF) was observed. A remarkable increase in shunt resistance of the cells with the MgF2 would possibly indicate that the highly resistive MgF2 layer can partly suppress physical shunting across top and bottom electrodes caused by very thin absorber thickness of only 100 nm. The approach showed that our best-performing device revealed an essential improvement in conversion efficiency from 7.83 to 8.01% with achieving markedly high V oc (1.013 V) and FF (0.729). [Figure not available: see fulltext.

  19. Screen printed interdigitated back contact solar cell

    NASA Astrophysics Data System (ADS)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T.

    1984-10-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  20. Screen printed interdigitated back contact solar cell

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T. (Inventor)

    1984-01-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  1. Structural dependences of localization and recombination of photogenerated carriers in the top GaInP Subcells of GaInP/GaAs double-junction tandem solar cells.

    PubMed

    Deng, Zhuo; Ning, Jiqiang; Su, Zhicheng; Xu, Shijie; Xing, Zheng; Wang, Rongxin; Lu, Shulong; Dong, Jianrong; Zhang, Baoshun; Yang, Hui

    2015-01-14

    In high-efficiency GaInP/GaAs double-junction tandem solar cells, GaInP layers play a central role in determining the performance of the solar cells. Therefore, gaining a deeper understanding of the optoelectronic processes in GaInP layers is crucial for improving the energy conversion efficiency of GaInP-based photovoltaic devices. In this work, we firmly show strong dependences of localization and recombination of photogenerated carriers in the top GaInP subcells in the GaInP/GaAs double-junction tandem solar cells on the substrate misorientation angle with excitation intensity- and temperature-dependent photoluminescence (PL). The entire solar cell structures including GaInP layers were grown with metalorganic chemical vapor deposition on GaAs substrates with misorientation angles of 2° (denoted as Sample 2°) and 7° (Sample 7°) off (100) toward (111)B. The PL spectral features of the two top GaInP subcells, as well as their excitation-power and temperature dependences exhibit remarkable variation on the misorientation angle. In Sample 2°, the dominant localization mechanism and luminescence channels are due to the energy potential minima caused by highly ordered atomic domains; In Sample 7°, the main localization and radiative recombination of photogenerated carriers occur in the atomically disordered regions. Our results reveal a more precise picture on the localization and recombination mechanisms of photogenerated carriers in the top GaInP subcells, which could be the crucial factors in controlling the optoelectronic efficiency of the GaInP-based multijunction photovoltaic devices.

  2. Design Rules for Efficient Organic Solar Cells

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Mühlbacher, D.; Morana, M.; Koppe, M.; Scharber, M. C.; Waller, D.; Dennler, G.; Brabec, C. J.

    There has been an intensive search for cost-effective photovoltaics since the development of the first solar cells in the 1950s [1-3]. Among all the alternative technologies to silicon-based pn-junction solar cells, organic solar cells are the approach that could lead to the most significant cost reduction [4]. The field of organic photovoltaics (OPV) is composed of organic/inorganic nanostructures, like the dyesensitized solar cell, multilayers of small organic molecules and mixtures of organic materials (bulk-heterojunction solar cell). A review of several so-called organic photovoltaic (OPV) technologies was recently presented [5].

  3. Silicon MINP solar cells

    NASA Technical Reports Server (NTRS)

    Olsen, L. C.; Addis, F. W.; Miller, W. A.

    1985-01-01

    The MINP solar cell concept refers to a cell structure designed to be a base region dominated device. Thus, it is desirable that recombination losses are reduced to the point that they occur only in the base region. The most unique feature of the MINP cell design is that a tunneling contact is utilized for the metallic contact on the front surface. The areas under the collector grid and bus bar are passivated by a thin oxide of tunneling thickness. Efforts must also be taken to minimize recombination at the surface between grid lines, at the junction periphery and within the emitter. Results of both theoretical and experimental studies of silicon MINP cells are given. Performance calculations are described which give expected efficiencies as a function of base resistivity and junction depth. Fabrication and characterization of cells are discussed which are based on 0.2 ohm-cm substrates, diffused emitters on the order of 0.15 to 0.20 microns deep, and with Mg MIS collector grids. A total area AM 1 efficiency of 16.8% was achieved. Detailed analyses of photocurrent and current loss mechanisms are presented and utilized to discuss future directions of research. Finally, results reported by other workers are discussed.

  4. The performances of silicon solar cell with core-shell p-n junctions of micro-nano pillars fabricated by cesium chloride self-assembly and dry etching

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Zhang, Xinshuai; Dong, Gangqiang; Liao, Yuanxun; Wang, Bo; Zhang, Tianchong; Yi, Futing

    2014-03-01

    Silicon micro-nano pillars are cost-efficiently integrated using twice cesium chloride (CsCl) islands lithography technique and dry etching for solar cell applications. The micro PMMA islands are fabricated by inductively coupled plasma (ICP) dry etching with micro CsCl islands as masks, and the nano CsCl islands with nano sizes then are made on the surface of micro PMMA islands and silicon. By ICP dry etching with the mask of micro PMMA islands and nano CsCl islands, the micro-nano silicon pillars are made and certain height micro pillars are randomly positioned between dense arrays of nano pillars with different morphologies by controlling etching conditions. With 300 nm depth p-n junction detected by secondary-ion mass spectrometry (SIMS), the micro pillars of the diameter about 1 μm form the core-shell p-n junction to maximize utility of p-n junction interface and enable efficient free carrier collection, and the nano tapered pillars of 150 nm diameter are used to decrease reflection by a graded-refractive-index. Compared to single micro or nano pillar arrayed cells, the co-integrated solar cell with micro and nano pillars demonstrates improved photovoltaic characteristic that is a photovoltaic conversion efficiency (PCE) of 15.35 % with a short circuit current density ( J sc) of 38.40 mA/cm2 and an open circuit voltage ( V oc) of 555.7 mV, which benefits from the advantages of micro-nano pillar structures and can be further improved upon process optimization.

  5. High Efficiency IMM Solar Cells

    NASA Astrophysics Data System (ADS)

    Sharps, P.; Cho, B.; Chumney, D.; Cornfeild, A.; Guzie, B.; Hazlett, D.; Lin, Y.; Mackos, C.; Patel, P.; Stan, M.; Steinfeldt, J.; Tourino, C.

    2014-08-01

    We review the status of currently available commercial multi-junction cells, review options for next generation high efficiency cell architectures, and present the latest developments on the inverted metamorphic multi- junction (IMM) solar cell. Over 20,000 IMM cells have been prototyped to date, and efficiencies of up to 37% have been measured. We present the most recent performance data, including the response to particle radiation. The IMM cell can be used in a number of rigid or flexible configurations, and considerable effort is currently focused on cell packaging and panel integration. We discuss several design options, including a "drop in" replacement for the current 29.5% ZTJ cell technology. We will also address the reliability and cost of the IMM cell.

  6. Monolithic and mechanical multijunction space solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1992-01-01

    High-efficiency, lightweight, radiation-resistant solar cells are essential to meet the large power requirements of future space missions. Single-junction cells are limited in efficiency. Higher cell efficiencies could be realized by developing multijunction, multibandgap solar cells. Monolithic and mechanically stacked tandem solar cells surpassing single-junction cell efficiencies have been fabricated. This article surveys the current status of monolithic and mechanically stacked multibandgap space solar cells, and outlines problems yet to be resolved. The monolithic and mechanically stacked cells each have their own problems related to size, processing, current and voltage matching, weight, and other factors. More information is needed on the effect of temperature and radiation on the cell performance. Proper reference cells and full-spectrum range simulators are also needed to measure efficiencies correctly. Cost issues are not addressed, since the two approaches are still in the developmental stage.

  7. A comparative study on charge carrier recombination across the junction region of Cu2ZnSn(S,Se)4 and Cu(In,Ga)Se2 thin film solar cells

    NASA Astrophysics Data System (ADS)

    Halim, Mohammad Abdul; Islam, Muhammad Monirul; Luo, Xianjia; Sakurai, Takeaki; Sakai, Noriyuki; Kato, Takuya; Sugimoto, Hiroki; Tampo, Hitoshi; Shibata, Hajime; Niki, Shigeru; Akimoto, Katsuhiro

    2016-03-01

    A comparative study with focusing on carrier recombination properties in Cu2ZnSn(S,Se)4 (CZTSSe) and the CuInGaSe2 (CIGS) solar cells has been carried out. For this purpose, electroluminescence (EL) and also bias-dependent time resolved photoluminescence (TRPL) using femtosecond (fs) laser source were performed. For the similar forward current density, the EL-intensity of the CZTSSe sample was obtained significantly lower than that of the CIGS sample. Primarily, it can be attributed to the existence of excess amount of non-radiative recombination center in the CZTSSe, and/or CZTSSe/CdS interface comparing to that of CIGS sample. In case of CIGS sample, TRPL decay time was found to increase with the application of forward-bias. This can be attributed to the reduced charge separation rate resulting from the reduced electric-field at the junction. However, in CZTSSe sample, TRPL decay time has been found almost independent under the forward and reverse-bias conditions. This phenomenon indicates that the charge recombination rate strongly dominates over the charge separation rate across the junction of the CZTSSe sample. Finally, temperature dependent VOC suggests that interface related recombination in the CZTSSe solar cell structure might be one of the major factors that affect EL-intensity and also, TRPL decay curves.

  8. New high-efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Crotty, G. T.

    1985-01-01

    A design for silicon solar cells was investigated as an approach to increasing the cell open-circuit voltage and efficiency for flat-plate terrestrial photovoltaic applications. This deviates from past designs, where either the entire front surface of the cell is covered by a planar junction or the surface is textured before junction formation, which results in an even greater (up to 70%) junction area. The heavily doped front region and the junction space charge region are potential areas of high recombination for generated and injected minority carriers. The design presented reduces junction area by spreading equidiameter dot junctions across the surface of the cell, spaced about a diffusion length or less from each other. Various dot diameters and spacings allowed variations in total junction area. A simplified analysis was done to obtain a first-order design optimization. Efficiencies of up to 19% can be obtained. Cell fabrication involved extra masking steps for selective junction diffusion, and made surface passivation a key element in obtaining good collection. It also involved photolithography, with line widths down to microns. A method is demonstrated for achieving potentially high open-circuit voltages and solar-cell efficiencies.

  9. The potential and device physics of interdigitated thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Metzger, Wyatt K.

    2008-05-01

    The device physics of thin-film solar cells with interdigitated p-n junctions is examined for a range of spatial sizes, band offsets, and material parameters. The results are illustrated by focusing on recent nanoscale concepts for Cu(In,Ga)Se2 solar cells. Ideally, nanoscale interdigitated junctions can improve solar cell performance relative to planar-junction devices, and make reasonably high solar cell efficiencies (>15%) attainable even with mediocre electro-optical materials.

  10. Absorption enhancement of GaInP nanowires by tailoring transparent shell thicknesses and its application in III-V nanowire/Si film two-junction solar cells.

    PubMed

    Li, Xinhua; Shi, Tongfei; Liu, Guangqiang; Wen, Long; Zhou, BuKang; Wang, Yuqi

    2015-09-21

    A non-absorbing transparent shell is proposed to be coated on the outer surface of the core photoactive GaInP nanowire array (NWA) of the III-V nanowire (NW)/Si film two-junction solar cell. Interestingly, the diluted (at the filling ratio of 0.25) GaInP NWA with core / transparent shell structure can absorb more light than that in bare denser (at the filling ratio of 0.5) NWA. This allows for less source material consumption during the fabrication of III-V NWA/Si film two-junction cell. Meanwhile, the condition of current matching between the top III-V NWA and Si film sub cell can be easily fulfilled by tailoring the coating thickness of the transparent coating. Beyond the advantages on light absorption, the surface passivation effects introduced by the addition of some transparent dielectric coatings can reduce the surface recombination rate at the top NWA sub cell surface. This facilitates the effective extraction of photo-generated carriers and enhances output stability of the top NWA sub cell. From electrical simulation, a power conversion efficiency of 29.9% can be obtained at the optimized coating geometry.

  11. Optimization of Phase-Engineered a-Si:H-Based Multi-Junction Solar Cells: Final Technical Report, October 2001-July 2005

    SciTech Connect

    Wronski, C. R.; Collins, R. W.; Podraza, N. J.; Vlahos, V.; Pearce, J. M.; Deng, J.; Albert, M.; Ferreira, G. M.; Chen, C.

    2006-08-01

    The scope of the work under this subcontract has involved investigating engineered improvements in the performance and stability of solar cells in a systematic way, which included the following four tasks: (1) Materials research and device development; (2) Process improvement directed by real time diagnostics; (3) Device loss mechanisms; and (4) Characterization strategies for advanced materials Our work has resulted in new and important insights into the deposition of a-Si:H-based materials, as well as into the nature of the Staebler-Wronski Effect (SWE). Presumably, many of these insights will be used by industrial partners to develop more systematic approaches in optimizing solar cells for higher performance and stability. This effort also cleared up several serious misconceptions about the nature of the p-layer in cells and the SWE in materials and cells. Finally, the subcontract identified future directions that should be pursued for greater understanding and improvement.

  12. Solar cell with a gallium nitride electrode

    DOEpatents

    Pankove, Jacques I.

    1979-01-01

    A solar cell which comprises a body of silicon having a P-N junction therein with a transparent conducting N-type gallium nitride layer as an ohmic contact on the N-type side of the semiconductor exposed to solar radiation.

  13. Developments toward an 18% efficient silicon solar cell

    NASA Technical Reports Server (NTRS)

    Meulenberg, A., Jr.

    1983-01-01

    Limitations to increased open-circuit voltage were identified and experimentally verified for 0.1 ohm-cm solar cells with heavily doped emitters. After major reduction in the dark current contribution from the metal-silicon interface of the grid contacts, the surface recombination velocity of the oxide-silicon interface of shallow junction solar cells is the limiting factor. In deep junction solar cells, where the junction field does not aid surface collection, the emitter bulk is the limiting factor. Singly-diffused, shallow junction cells have been fabricated with open circuit voltages in excess of 645 mV. Double-diffusion shallow and deep junctions cells have displayed voltages above 650 mV. MIS solar cells formed on 0.1 ohm-cm substrates have exibited the lowest dark currents produced in the course of the contract work.

  14. High Radiation Resistance IMM Solar Cell

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  15. High-efficiency solar cell and method for fabrication

    DOEpatents

    Hou, H.Q.; Reinhardt, K.C.

    1999-08-31

    A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD). 4 figs.

  16. High-efficiency solar cell and method for fabrication

    DOEpatents

    Hou, Hong Q.; Reinhardt, Kitt C.

    1999-01-01

    A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD).

  17. New developments in silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lindmayer, J.

    1978-01-01

    Three areas of silicon solar cell development are discussed. The first area relates to ultra thin cells about 50 microns in thickness, which can be made with relative good yield and efficiency. The second describes a new effort in vertical junction cells which show increased efficiency and continues to improve. The third area describes our semicrystalline silicon work which resulted in silicon solar cells that show over 10% terrestrial conversion efficiency and are tolerant to impurities.

  18. Performance of High-Efficiency Advanced Triple-Junction Solar Panels for the LILT Mission Dawn

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Sharma, Surya; Buitrago, Oscar; Sharps, Paul R.; Blok, Ron; Kroon, Martin; Jalink, Cees; Harris, Robin; Stella, Paul; Distefano, Sal

    2005-01-01

    NASA's Discovery Mission Dawn is designed to (LILT) conditions. operate within the solar system's Asteroid belt, where the large distance from the sun creates a low-intensity, low-temperature (LILT) condition. To meet the mission power requirements under LlLT conditions, very high-efficiency multi-junction solar cells were selected to power the spacecraft to be built by Orbital Sciences Corporation (OSC) under contract with JPL. Emcore's InGaP/InGaAs/Ge advanced triple-junction (ATJ) solar cells, exhibiting an average air mass zero (AMO) efficiency of greater than 27.6% (one-sun, 28 C), were used to populate the solar panels [1]. The two solar array wings, to be built by Dutch Space, with 5 large- area panels each (total area of 36.4 sq. meters) are projected to produce between 10.3 kWe and 1.3 kWe of end-of life (EOL) power in the 1.0 to 3.0 AU range, respectively. The details of the solar panel design, testing and power analysis are presented.

  19. Further aspects of damage-induced junction mechanisms and the role of phosphorus movement in double-layer in-chamber annealed In-Sn/ITO/InP solar cells

    NASA Astrophysics Data System (ADS)

    Henry, J.; Livingstone, J.

    1998-04-01

    The research effort dedicated to sputtered indium tin oxide/indium phosphide solar cells has yet to produce a definitive model of the junction that takes account of all of the experimental evidence. The work here reports on a two-layer structure which was originally developed to avoid the surface degradation of bare InP that occurs under high-temperature processing conditions, but was found also to assist in the elucidation of some of the mechanisms, particularly the role of hydrogen and phosphorus movement, involved in ITO/InP cell performance. This two-layer technique effected marked improvements in output properties, which have previously been reported, and now we outline proposed operating mechanisms based on these results and on the work of other researchers in the area.

  20. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    SciTech Connect

    Tex, David M.; Ihara, Toshiyuki; Kanemitsu, Yoshihiko; Akiyama, Hidefumi; Imaizumi, Mitsuru

    2015-01-05

    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  1. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Tex, David M.; Ihara, Toshiyuki; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  2. Organic Tandem Solar Cells: Design and Formation

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Chao

    In the past decade, research on organic solar cells has gone through an important development stage leading to major enhancements in power conversion efficiency, from 4% to 9% in single-junction devices. During this period, there are many novel processing techniques and device designs that have been proposed and adapted in organic solar-cell devices. One well-known device architecture that helps maximize the solar cell efficiency is the multi-junction tandem solar-cell design. Given this design, multiple photoactive absorbers as subcells are stacked in a monolithic fashion and assembled via series connection into one complete device, known as the tandem solar cell. Since multiple absorbers with different optical energy bandgaps are being applied in one tandem solar-cell device, the corresponding solar cell efficiency is maximized through expanded absorption spectrum and reduced carrier thermalization loss. In Chapter 3, the architecture of solution-processible, visibly transparent solar cells is introduced. Unlike conventional organic solar-cell devices with opaque electrodes (such as silver, aluminum, gold and etc.), the semi-transparent solar cells rely on highly transparent electrodes and visibly transparent photoactive absorbers. Given these two criteria, we first demonstrated the visibly transparent single-junction solar cells via the polymer absorber with near-infrared absorption and the top electrode based on solution-processible silver nanowire conductor. The highest visible transparency (400 ˜ 700 nm) of 65% was achieved for the complete device structure. More importantly, power conversion efficiency of 4% was also demonstrated. In Chapter 4, we stacked two semi-transparent photoactive absorbers in the tandem architecture in order to realize the semi-transparent tandem solar cells. A noticeable performance improvement from 4% to 7% was observed. More importantly, we modified the interconnecting layers with the incorporation of a thin conjugated

  3. Method for processing silicon solar cells

    DOEpatents

    Tsuo, Y.S.; Landry, M.D.; Pitts, J.R.

    1997-05-06

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystalline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation. 2 figs.

  4. Method for processing silicon solar cells

    DOEpatents

    Tsuo, Y. Simon; Landry, Marc D.; Pitts, John R.

    1997-01-01

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystallline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation.

  5. The Performance of Advanced III-V Solar Cells

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.; Gaddy, Edward; Day, John H. (Technical Monitor)

    2002-01-01

    Test results show triple junction solar cells with efficiencies as high as 27% at 28C and 136.7 mw/sq cm. Triple junction cells also achieve up to 27.5% at -120 C and 5 mw/sq cm, conditions applicable to missions to Jupiter. Some triple junction cells show practically no degradation as a result of Low Intensity Low Temperature (LILT) effects, while others show some; this degradation can be overcome with minor changes to the cell design.

  6. A theoretical analysis of the current-voltage characteristics of solar cells

    NASA Technical Reports Server (NTRS)

    Fang, R. C. Y.; Hauser, J. R.

    1979-01-01

    The following topics are discussed: (1) dark current-voltage characteristics of solar cells; (2) high efficiency silicon solar cells; (3) short circuit current density as a function of temperature and the radiation intensity; (4) Keldysh-Franz effects and silicon solar cells; (5) thin silicon solar cells; (6) optimum solar cell designs for concentrated sunlight; (7) nonuniform illumination effects of a solar cell; and (8) high-low junction emitter solar cells.

  7. Thin foil silicon solar cells with coplanar back contacts

    NASA Technical Reports Server (NTRS)

    Ho, F.; Iles, P. A.; Baraona, C. R.

    1981-01-01

    To fabricate 50 microns thick, coplanar back contact (CBC) silicon solar cells, wraparound junction design was selected and proved to be effective. The process sequence used, the cell design, and the cell performance are described. CBC cells with low solar absorptance have shown AMO efficiencies to 13%, high cells up to 14%; further improvements are projected with predictable optimization.

  8. STUDIES ON AN EPITHELIAL (GLAND) CELL JUNCTION

    PubMed Central

    Loewenstein, Werner R.; Kanno, Yoshinobu

    1964-01-01

    Membrane permeability of an epithelial cell junction (Drosophila salivary gland) was examined with intracellular microelectrodes and with fluorescent tracers. In contrast to the non-junctional cell membrane surface, which has a low permeability to ions (10-4 mho/cm2), the junctional membrane surface is highly permeable. In fact, it introduces no substantial restriction to ion flow beyond that in the cytoplasm; the resistance through a chain of cells (150 Ω cm) is only slightly greater than in extruded cytoplasm (100 Ω cm). The diffusion resistance along the intercellular space to the exterior, on the other hand, is very high. Here, there exists an ion barrier of, at least, 104Ω cm2. As a result, small ions and fluorescein move rather freely from one cell to the next, but do not leak appreciably through the intercellular space to the exterior. The organ here, rather than the single cell, appears to be the unit of ion environment. The possible underlying structural aspects are discussed. PMID:14206423

  9. Front contact solar cell with formed emitter

    DOEpatents

    Cousins, Peter John [Menlo Park, CA

    2012-07-17

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  10. Front contact solar cell with formed emitter

    DOEpatents

    Cousins, Peter John

    2014-11-04

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  11. Amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Takahashi, K.; Konagai, M.

    The fabrication, performance, and applications of a-Si solar cells are discussed, summarizing the results of recent experimental investigations and trial installations. Topics examined include the fundamental principles and design strategies of solar power installations; the characteristics of monocrystalline-Si solar cells; techniques for reducing the cost of solar cells; independent, linked, and hybrid solar power systems; proposed satellite solar power systems; and the use of solar cells in consumer appliances. Consideration is given to the history of a-Si, a-Si fabrication techniques, quality criteria for a-Si films, solar cells based on a-Si, and techniques for increasing the efficiency and lowering the cost of a-Si solar cells. Graphs, diagrams, drawings, and black-and-white and color photographs are provided.

  12. NREL Studies Carrier Separation and Transport in Perovskite Solar Cells

    SciTech Connect

    2016-01-01

    NREL scientists studied charge separation and transport in perovskite solar cells by determining the junction structure across the solar device using the nanoelectrical characterization technique of Kelvin probe force microscopy. The distribution of electrical potential across both planar and porous devices demonstrates a p-n junction structure at the interface between titanium dioxide and perovskite. In addition, minority-carrier transport within the devices operates under diffusion/drift. Clarifying the fundamental junction structure provides significant guidance for future research and development. This NREL study points to the fact that improving carrier mobility is a critical factor for continued efficiency gains in perovskite solar cells.

  13. Plasmon resonance energy transfer and hot electron injection induced high photocurrent density in liquid junction Ag@Ag2S sensitized solar cells.

    PubMed

    Wu, Dapeng; Wang, Fujuan; Wang, Hongju; Cao, Kun; Gao, Zhiyong; Xu, Fang; Jiang, Kai

    2016-10-18

    An in situ technique was developed to deposit Ag@Ag2S core-shell quantum dots on a SnO2 mesoporous film for solar energy conversion. When adopted as a photoanode, an impressive high photocurrent density of ∼25.6 mA cm(-2) was demonstrated in a cell configuration using polysulfide S(2-)/Sn(2-) as an electrolyte and Cu2S/brass as a counter electrode, which leads to a power conversion efficiency of ∼0.784% for this environmentally benign device. Optical measurements showed that Ag nanoparticles could be employed as plasmon resonance centers to enhance the harvesting efficiency of incident light at the visible and near-infrared range. Moreover, photoluminescence spectra demonstrated fast charge transfer at Ag@Ag2S/SnO2 interfaces, which facilitates direct hot electron injection from sensitizers to the SnO2 matrix and finally gives rise to the high photocurrent density.

  14. Solar Photovoltaic Cells.

    ERIC Educational Resources Information Center

    Mickey, Charles D.

    1981-01-01

    Reviews information on solar radiation as an energy source. Discusses these topics: the key photovoltaic material; the bank theory of solids; conductors, semiconductors, and insulators; impurity semiconductors; solid-state photovoltaic cell operation; limitations on solar cell efficiency; silicon solar cells; cadmium sulfide/copper (I) sulfide…

  15. Indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, Irving

    1991-01-01

    The direction for InP solar cell research; reduction of cell cost; increase of cell efficiency; measurements needed to better understand cell performance; n/p versus p/n; radiation effects; major problems in cell contacting; and whether the present level of InP solar cell research in the USA should be maintained, decreased, or increased were considered.

  16. A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells

    PubMed Central

    Guo, Fei; Li, Ning; Fecher, Frank W.; Gasparini, Nicola; Quiroz, Cesar Omar Ramirez; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V.; Radmilović, Velimir R.; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J.

    2015-01-01

    The multi-junction concept is the most relevant approach to overcome the Shockley–Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies. PMID:26177808

  17. A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells.

    PubMed

    Guo, Fei; Li, Ning; Fecher, Frank W; Gasparini, Nicola; Ramirez Quiroz, Cesar Omar; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V; Radmilović, Velimir R; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

    2015-07-16

    The multi-junction concept is the most relevant approach to overcome the Shockley-Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies.

  18. A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Guo, Fei; Li, Ning; Fecher, Frank W.; Gasparini, Nicola; Quiroz, Cesar Omar Ramirez; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V.; Radmilović, Velimir R.; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J.

    2015-07-01

    The multi-junction concept is the most relevant approach to overcome the Shockley-Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies.

  19. New Thin Film CuGaSe2/Cu(In,Ga)Se2 Bifacial, Tandem Solar Cell with Both Junctions Formed Simultaneously

    SciTech Connect

    Young, D. L.; Abu-Shama, J.; Noufi, R.; Li, X.; Keane, J.; Gessert, T. A.; Ward, J. S.; Contreas, M.; Symko-Davies, M.; Coutts, T. J.

    2002-05-01

    Thin films of CuGaSe2 and Cu(In,Ga)Se2 were evaporated by the 3-stage process onto opposite sides of a single piece of soda-lime glass, coated bifacially with an n+/-TCO. Junctions were formed simultaneously with each of the p-type absorbers by depositing thin films of n-CdS via chemical bath deposition (CBD) at 60C. The resulting four-terminal device is a non-mechanically stacked, two-junction tandem. The unique growth sequence protects the temperature-sensitive p/n junctions. The initial device (h= 3.7%, Voc= 1.1 V[AM1.5]) suffered from low quantum efficiencies. Initial results are also presented from experiments with variations in growth sequence and back reflectors.

  20. Electron irradiation of modern solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.

    1977-01-01

    A number of modern solar cell types representing 1976 technology (as well as some older types) were irradiated with 1 MeV electrons (and a limited number with 2 MeV electrons and 10 MeV protons). After irradiation, the cells were annealed, with I-V curves measured under AMO at 30 C. The purpose was to provide data to be incorporated in the revision of the solar cell radiation handbook. Cell resistivities ranged from 2 to 20 ohm-cm, and cell thickness from 0.05 to 0.46 mm. Cell types examined were conventional, shallow junction, back surface field (BSF), textured, and textured with BSF.

  1. A novel maskless approach towards aligned, density modulated and multi-junction ZnO nanowires for enhanced surface area and light trapping solar cells.

    PubMed

    Kevin, M; Fou, Y H; Wong, A S W; Ho, G W

    2010-08-06

    A maskless method of employing polymer growth inhibitor layers is used to modulate the conflicting parameters of density and alignment of multi-junction nanowires via large-scale low temperature chemical route. This low temperature chemical route is shown to synthesize multi-junction nanostructures without compromising the crystal quality at the interfaces. The final morphology of optimized multi-junctions nanowire arrays can be demonstrated on various substrates due to substrate independence and low temperature processing. Here, we also fabricated devices based on density modulated multi-junction nanowires tuned to infiltrate nanoparticles. The fabrication of hierarchically structured nanowire/nanoparticles composites presents an advantageous structure, one that allows nanoparticles to provide large surface areas for dye adsorption, whilst the nanowires can enhance the light harvesting, electron transport rate, and also the mechanical properties of the films. This work can be of great scientific and commercial interest since the technique employed is of low temperature (<90 degrees C) and economical for large-scale solution processing, much valued in today's flexible display and photovoltaic industries.

  2. Plastic Schottky-barrier solar cells

    DOEpatents

    Waldrop, J.R.; Cohen, M.J.

    1981-12-30

    A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

  3. Studies of heteroface solar cell performance

    NASA Technical Reports Server (NTRS)

    Feucht, D. L.; Milnes, A. G.

    1975-01-01

    The development, fabrication, and failure modes of AlxGa(1-x)As-GaAs heteroface solar cells are described. Crystal growth, the diffusion of Zn into the GaAs layer to form the p-n junction, SEM studies of the diffusion length of GaAs, and procedures for making ohmic contacts are discussed.

  4. Concentrator Solar Cell Production Capability and Laboratory Results at Emcore

    NASA Astrophysics Data System (ADS)

    Aiken, Daniel; Aeby, Ian; Clevenger, Brad; Newman, Fred; Patel, Pravin; Sharps, Paul; Stan, Mark; Varghese, Tansen; Wood, Jody

    2010-10-01

    Manufacturing capability is discussed including production capacity for both solar cells and packaged receiver sub assemblies, and the flash test/sort/inspection tooling and methods that have allowed this production capacity. Laboratory solar cell development results are presented, including quadruple junction inverted metamorphic solar cells with an efficiency of 33.6% under AM0 illumination at 28° C. Computational models are used to predict 43% conversion efficiency at 500 suns if this technology is successfully adapted to concentrating applications using the materials and processes now available. A temperature coefficient modeling study suggests that these four junction solar cells will degrade faster at elevated temperature than will comparable technology triple junction solar cells.

  5. Investigation of the electric field in TiO2/FTO junctions used in dye-sensitized solar cells by photocurrent transients.

    PubMed

    Rühle, Sven; Dittrich, Thomas

    2005-05-19

    We have investigated the electrostatic potential distribution in compact and nanoporous TiO2 films, deposited on conducting F-doped SnO2 substrate (FTO), which are used in dye-sensitized solar cells. The TiO2 films were immersed into aqueous electrolyte and excited from the FTO side by light pulses of a N2 laser while the current response was measured as a function of time. The measurements were carried out as a function of the pH value of the electrolyte and at different electrostatic potentials. For compact TiO2 films, the sign of the transient current at short response times changed when the applied electrostatic potential or the pH value was decreased. This was not observed for mesoporous TiO2 films directly deposited onto the FTO substrate without a compact TiO2 layer. We interpret the results in terms of a macroscopic electric field across the compact layer which is changed by the applied potential or the pH of the electrolyte. In contrast, measurements on mesoporous TiO2 films indicate that the contact region is mainly field-free, and we explain our results by a very sharp electrostatic potential drop within the first layer of particles at the TiO2/FTO interface.

  6. Planar multijunction high voltage solar cells

    NASA Astrophysics Data System (ADS)

    Evans, J. C., Jr.; Chai, A. T.; Goradia, C.

    1980-01-01

    Technical considerations, preliminary results, and fabrication details are discussed for a family of high-voltage planar multi-junction (PMJ) solar cells which combine the attractive features of planar cells with conventional or interdigitated back contacts and the vertical multijunction (VMJ) solar cell. The PMJ solar cell is internally divided into many voltage-generating regions, called unit cells, which are internally connected in series. The key to obtaining reasonable performance from this device was the separation of top surface field regions over each active unit cell. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per linear centimeter are possible. Analysis of the new device is complex, and numerous geometries are being studied which should provide substantial benefits in both normal sunlight usage as well as with concentrators.

  7. A proposed route to independent measurements of tight junction conductance at discrete cell junctions

    PubMed Central

    Zhou, Lushan; Zeng, Yuhan; Baker, Lane A; Hou, Jianghui

    2015-01-01

    Direct recording of tight junction permeability is of pivotal importance to many biologic fields. Previous approaches bear an intrinsic disadvantage due to the difficulty of separating tight junction conductance from nearby membrane conductance. Here, we propose the design of Double whole-cell Voltage Clamp - Ion Conductance Microscopy (DVC-ICM) based on previously demonstrated potentiometric scanning of local conductive pathways. As proposed, DVC-ICM utilizes two coordinated whole-cell patch-clamps to neutralize the apical membrane current during potentiometric scanning, which in models described here will profoundly enhance the specificity of tight junction recording. Several potential pitfalls are considered, evaluated and addressed with alternative countermeasures. PMID:26716077

  8. Theoretical efficiency limit for a two-terminal multi-junction "step-cell" using detailed balance method

    NASA Astrophysics Data System (ADS)

    Abdul Hadi, Sabina; Fitzgerald, Eugene A.; Nayfeh, Ammar

    2016-02-01

    Here we present detailed balance efficiency limit for a novel two-terminal dual and triple junction "step-cell" under AM 1.5G and AM 0 incident spectrums. The step-cell is a multi-junction (MJ) solar cell in which part of the top cell is removed, exposing some of the bottom cell area to unfiltered incident light, thus increasing bottom cell's photogenerated current. Optical generation of the bottom cell is modeled in two parts: step part, limited by the bottom cell bandgap, and conventional part, additionally limited by the top cell absorption. Our results show that conventionally designed MJ cell with optimized bandgap combination of 1.64 eV/0.96 eV for dual junction and 1.91 eV/1.37 eV/0.93 eV for triple junction has the highest theoretical efficiency limit. However, the step-cell design provides significant efficiency improvement for cells with non-optimum bandgap values. For example, for 1.41 eV ( ˜GaAs)/Si dual junction under AM 1.5G, efficiency limit increases from ˜21% in a conventional design to 38.7% for optimized step-cell. Similar benefits are observed for three-junction step-cell and for AM 0 spectrum studied here. Step-cell relaxes bandgap requirements for efficient MJ solar cells, providing an opportunity for a wider selection of materials and cost reduction.

  9. Heterojunction solar cell

    DOEpatents

    Olson, J.M.

    1994-08-30

    A high-efficiency single heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the emitter layer. 1 fig.

  10. Heterojunction solar cell

    DOEpatents

    Olson, Jerry M.

    1994-01-01

    A high-efficiency single heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. The conversion effiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the emitter layer.

  11. Solar cell encapsulation

    NASA Technical Reports Server (NTRS)

    Gupta, Amitava (Inventor); Ingham, John D. (Inventor); Yavrouian, Andre H. (Inventor)

    1983-01-01

    A polymer syrup for encapsulating solar cell assemblies. The syrup includes uncrosslinked poly(n-butyl)acrylate dissolved in n-butyl acrylate monomer. Preparation of the poly(n-butyl)acrylate and preparation of the polymer syrup is disclosed. Methods for applying the polymer syrup to solar cell assemblies as an encapsulating pottant are described. Also included is a method for solar cell construction utilizing the polymer syrup as a dual purpose adhesive and encapsulating material.

  12. Investigation of GaInAs strain reducing layer combined with InAs quantum dots embedded in Ga(In)As subcell of triple junction GaInP/Ga(In)As/Ge solar cell.

    PubMed

    Li, Senlin; Bi, Jingfeng; Li, Mingyang; Yang, Meijia; Song, Minghui; Liu, Guanzhou; Xiong, Weiping; Li, Yang; Fang, Yanyan; Chen, Changqing; Lin, Guijiang; Chen, Wenjun; Wu, Chaoyu; Wang, Duxiang

    2015-01-01

    The InAs/GaAs quantum dots structure embedded in GaInP/Ga(In)As/Ge triple junction solar cell with and without Ga0.90In0.10As strain reducing layer was investigated. Conversion efficiency of 33.91% at 1,000 suns AM 1.5D with Ga0.90In0.10As strain reducing layer was demonstrated. A 1.19% improvement of the conversion efficiency was obtained via inserting the Ga0.90In0.10As strain reducing layer. The main contribution of this improvement was from the increase of the short-circuit current, which is caused by the reduction of the Shockley-Read-Hall recombination centers. Consequently, there was a decrease in open circuit voltage due to the lower thermal activation energy of confined carriers in Ga0.9In0.1As than GaAs and a reduction in the effective band gap of quantum dots.

  13. Electrostatic Discharge Test of Multi-Junction Solar Array Coupons After Combined Space Environmental Exposures

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Schneider, Todd; Vaughn, Jason; Hoang, Bao; Funderburk, Victor V.; Wong, Frankie; Gardiner, George

    2010-01-01

    A set of multi-junction GaAs/Ge solar array test coupons were subjected to a sequence of 5-year increments of combined environmental exposure tests. The test coupons capture an integrated design intended for use in a geosynchronous (GEO) space environment. A key component of this test campaign is conducting electrostatic discharge (ESD) tests in the inverted gradient mode. The protocol of the ESD tests is based on the ISO/CD 11221, the ISO standard for ESD testing on solar array panels. This standard is currently in its final review with expected approval in 2010. The test schematic in the ISO reference has been modified with Space System/Loral designed circuitry to better simulate the on-orbit operational conditions of its solar array design. Part of the modified circuitry is to simulate a solar array panel coverglass flashover discharge. All solar array coupons used in the test campaign consist of 4 cells. The ESD tests are performed at the beginning of life (BOL) and at each 5-year environment exposure point. The environmental exposure sequence consists of UV radiation, electron/proton particle radiation, thermal cycling, and ion thruster plume. This paper discusses the coverglass flashover simulation, ESD test setup, and the importance of the electrical test design in simulating the on-orbit operational conditions. Results from 5th-year testing are compared to the baseline ESD characteristics determined at the BOL condition.

  14. Behavior of interdigitated back-contact solar cells

    NASA Technical Reports Server (NTRS)

    Cheng, L. J.; Leung, D. C.

    1980-01-01

    This paper presents experimental data concerning operation mechanisms of two versions of interdigitated back-contact solar cells: the tandem junction cell and the front-surface field cell. It is shown that a photogenerated forward bias at the front junction of a tandem junction cell is a critical parameter for cell performance which not only causes photogenerated carriers to migrate to the back junction, but also eliminates the reduction in photoresponse over back p(+) metallization regions. However, no similar light effects are observed in the performance of front-surface field cells. Finally, a discussion on mechanisms concerning the performance of front-surface field and tandem junction cells along with their merits is given.

  15. Development of GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Mcnally, P. J.

    1972-01-01

    Calculations of GaAs solar cell output parameters were refined and a computer model was developed for parameter optimization. The results were analyzed to determine the material characteristics required for a high efficiency solar cell. Calculated efficiencies for a P/N cell polarity are higher than an N/P cell. Both cell polarities show efficiency to have a larger dependence on short circuit current than an open circuit voltage under nearly all conditions considered. The tolerances and requirements of a cell fabrication process are more critical for an N/P type than for a P/N type cell. Several solar cell fabrication considerations relative to junction formation using ion implantation are also discussed.

  16. Concept of epitaxial silicon structures for edge illuminated solar cells

    NASA Astrophysics Data System (ADS)

    Sarnecki, J.; Gawlik, G.; Teodorczyk, M.; Jeremiasz, O.; Kozłowski, R.; Lipiński, D.; Krzyżak, K.; Brzozowski, A.

    2011-12-01

    A new concept of edge illuminated solar cells (EISC) based on silicon epitaxial technique has been proposed. In this kind of photovoltaic (PV) devices, sun-light illuminates directly a p-n junction through the edge of the structure which is perpendicular to junction surface. The main motivation of the presented work is preparation of a working model of an edge-illuminated silicon epitaxial solar cell sufficient to cooperation with a luminescent solar concentrator (LSC) consisted of a polymer foil doped with a luminescent material. The technological processes affecting the cell I-V characteristic and PV parameters are considered.

  17. Germanium Nanocrystal Solar Cells

    NASA Astrophysics Data System (ADS)

    Holman, Zachary Charles

    Greenhouse gas concentrations in the atmosphere are approaching historically unprecedented levels from burning fossil fuels to meet the ever-increasing world energy demand. A rapid transition to clean energy sources is necessary to avoid the potentially catastrophic consequences of global warming. The sun provides more than enough energy to power the world, and solar cells that convert sunlight to electricity are commercially available. However, the high cost and low efficiency of current solar cells prevent their widespread implementation, and grid parity is not anticipated to be reached for at least 15 years without breakthrough technologies. Semiconductor nanocrystals (NCs) show promise for cheap multi-junction photovoltaic devices. To compete with photovoltaic materials that are currently commercially available, NCs need to be inexpensively cast into dense thin films with bulk-like electrical mobilities and absorption spectra that can be tuned by altering the NC size. The Group II-VI and IV-VI NC communities have had some success in achieving this goal by drying and then chemically treating colloidal particles, but the more abundant and less toxic Group IV NCs have proven more challenging. This thesis reports thin films of plasma-synthesized Ge NCs deposited using three different techniques, and preliminary solar cells based on these films. Germanium tetrachloride is dissociated in the presence of hydrogen in a nonthermal plasma to nucleate Ge NCs. Transmission electron microscopy and X-ray diffraction indicate that the particles are nearly monodisperse (standard deviations of 10-15% the mean particle diameter) and the mean diameter can be tuned from 4-15 nm by changing the residence time of the Ge NCs in the plasma. In the first deposition scheme, a Ge NC colloid is formed by reacting nanocrystalline powder with 1-dodecene and dispersing the functionalized NCs in a solvent. Films are then formed on substrates by drop-casting the colloid and allowing it to dry

  18. Space solar cell research

    NASA Technical Reports Server (NTRS)

    Flood, Dennis J.

    1989-01-01

    A brief overview is given of the scope of the NASA space solar cell research and development program. Silicon cells, gallium arsenide cells, indium phosphide cells, and superlattice solar cells are addressed, indicating the state of the art of each type in outer space and their advantages and drawbacks for use in outer space. Contrasts between efficiency in space and on earth are pointed out.

  19. Practical high efficiency bifacial solar cells

    SciTech Connect

    Moehlecke, A.; Zanesco, I.; Luque, A.

    1994-12-31

    In this paper, the authors present a practical process to obtain bifacial solar cells. These cells are made using p{sup +}nn{sup +} structure on high-medium base resistivity, continuous emitters and with a process that maintains high bulk minority carrier lifetime. Efficiencies of 19.1% and 18.1% are achieved under standard conditions when the cell is illuminated by n{sup +}n high-low junction and when it is illuminated by P{sup +}n junction, respectively. The authors remark that the n{sup +}n high-low junction provides a higher current density and a good ratio between generated current of each face is found to be of about 103%.

  20. Solar cell shingle

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Ratajczak, A. F.; Sidorak, L. G. (Inventor)

    1977-01-01

    A solar cell shingle was made of an array of solar cells on a lower portion of a substantially rectangular shingle substrate made of fiberglass cloth or the like. The solar cells may be encapsulated in flourinated ethylene propylene or some other weatherproof translucent or transparent encapsulant to form a combined electrical module and a roof shingle. The interconnected solar cells were connected to connectors at the edge of the substrate through a connection to a common electrical bus or busses. An overlap area was arranged to receive the overlap of a cooperating similar shingle so that the cell portion of the cooperating shingle may overlie the overlap area of the roof shingle. Accordingly, the same shingle serves the double function of an ordinary roof shingle which may be applied in the usual way and an array of cooperating solar cells from which electrical energy may be collected.

  1. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    PubMed Central

    Martí, A.; Luque, A.

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base–emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers that are required to match the limiting efficiency of dual-junction solar cells without using tunnel junctions. The device naturally emerges as a three-terminal solar cell and can also be used as building block of multijunction solar cells with an increased number of junctions. PMID:25902374

  2. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion.

    PubMed

    Martí, A; Luque, A

    2015-04-22

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base-emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers that are required to match the limiting efficiency of dual-junction solar cells without using tunnel junctions. The device naturally emerges as a three-terminal solar cell and can also be used as building block of multijunction solar cells with an increased number of junctions.

  3. Heavily doped polysilicon-contact solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.; Arienzo, M.; Iles, P. A.

    1985-01-01

    The first use of a (silicon)/heavily doped polysilicon)/(metal) structure to replace the conventional high-low junction or back-surface-field (BSF) structure of silicon solar cells is reported. Compared with BSF and back-ohmic-contact (BOC) control samples, the polysilicon-back solar cells show improvements in red spectral response (RSR) and open-circuit voltage. Measurement reveals that a decrease in effective surface recombination velocity S is responsible for this improvement. Decreased S results for n-type (Si:As) polysilicon, consistent with past findings for bipolar transistors, and for p-type (Si:B) polysilicon, reported here for the first time. Though the present polysilicon-back solar cells are far from optimal, the results suggest a new class of designs for high efficiency silicon solar cells. Detailed technical reasons are advanced to support this view.

  4. Method of making a back contacted solar cell

    DOEpatents

    Gee, James M.

    1995-01-01

    A back-contacted solar cell having laser-drilled vias connecting the front-surface carrier-collector junction to an electrode grid on the back surface. The structure may also include a rear surface carrier-collector junction connected to the same grid. The substrate is connected to a second grid which is interdigitated with the first. Both grids are configured for easy series connection with neighboring cells. Several processes are disclosed to produce the cell.

  5. Method of making a back contacted solar cell

    DOEpatents

    Gee, J.M.

    1995-11-21

    A back-contacted solar cell is described having laser-drilled vias connecting the front-surface carrier-collector junction to an electrode grid on the back surface. The structure may also include a rear surface carrier-collector junction connected to the same grid. The substrate is connected to a second grid which is interdigitated with the first. Both grids are configured for easy series connection with neighboring cells. Several processes are disclosed to produce the cell. 2 figs.

  6. Heterostructure solar cells

    NASA Technical Reports Server (NTRS)

    Chang, K. I.; Yeh, Y. C. M.; Iles, P. A.; Morris, R. K.

    1987-01-01

    The performance of gallium arsenide solar cells grown on Ge substrates is discussed. In some cases the substrate was thinned to reduce overall cell weight with good ruggedness. The conversion efficiency of 2 by 2 cm cells under AMO reached 17.1 percent with a cell thickness of 6 mils. The work described forms the basis for future cascade cell structures, where similar interconnecting problems between the top cell and the bottom cell must be solved. Applications of the GaAs/Ge solar cell in space and the expected payoffs are discussed.

  7. Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

    DOEpatents

    Carlson, David E.

    1980-01-01

    Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

  8. Applications of ion implantation to high performance, radiation tolerant silicon solar cells

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, A. R.; Minnucci, J. A.; Matthei, K. W.

    1979-01-01

    Progress in the development of ion implanted silicon solar cells is reported. Effective back surface preparation by implantation, junction processing to achieve high open circuit voltages in low-resistivity cells, and radiation tolerance cells are among the topics studied.

  9. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.

    1977-01-01

    Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

  10. Monolithic DSSC/CIGS tandem solar cell fabricated by a solution process.

    PubMed

    Moon, Sung Hwan; Park, Se Jin; Kim, Sang Hoon; Lee, Min Woo; Han, Jisu; Kim, Jin Young; Kim, Honggon; Hwang, Yun Jeong; Lee, Doh-Kwon; Min, Byoung Koun

    2015-03-11

    Tandem architecture between organic (dye-sensitized solar cell, DSSC) and inorganic (CuInGaSe2 thin film solar cell, CIGS) single-junction solar cells was constructed particularly based on a solution process. Arc-plasma deposition was employed for the Pt interfacial layer to minimize the damage to the layers of the CIGS bottom cell. Solar cell efficiency of 13% was achieved, which is significant progress from individual single-junction solar cells (e.g., 7.25 and 6.2% for DSSC and CIGS, respectively).

  11. Monolithic DSSC/CIGS tandem solar cell fabricated by a solution process

    PubMed Central

    Moon, Sung Hwan; Park, Se Jin; Kim, Sang Hoon; Lee, Min Woo; Han, Jisu; Kim, Jin Young; Kim, Honggon; Hwang, Yun Jeong; Lee, Doh-Kwon; Min, Byoung Koun

    2015-01-01

    Tandem architecture between organic (dye-sensitized solar cell, DSSC) and inorganic (CuInGaSe2 thin film solar cell, CIGS) single-junction solar cells was constructed particularly based on a solution process. Arc-plasma deposition was employed for the Pt interfacial layer to minimize the damage to the layers of the CIGS bottom cell. Solar cell efficiency of 13% was achieved, which is significant progress from individual single-junction solar cells (e.g., 7.25 and 6.2% for DSSC and CIGS, respectively). PMID:25759191

  12. Asymmetric tandem organic solar cells

    NASA Astrophysics Data System (ADS)

    Howells, Thomas J.

    Organic photovoltaics (OPVs) is an area that has attracted much attention recently as a potential low cost, sustainable source of energy with a good potential for full-scale commercialisation. Understanding the factors that determine the efficiency of such cells is therefore a high priority, as well as developing ways to boost efficiency to commercially-useful levels. In addition to an intensive search for new materials, significant effort has been spent on ways to squeeze more performance out of existing materials, such as multijunction cells. This thesis investigates double junction tandem cells in the context of small molecule organic materials. . Two different organic electron donor materials, boron subphthalocyanine chloride (SubPc) and aluminium phthalocyanine chloride (ClAlPc) were used as donors in heterojunctions with C60 to create tandem cells for this thesis. These materials have been previously used for solar cells and the absorption spectra of the donor materials complement each other, making them good candidates for tandem cell architectures. The design of the recombination layer between the cells is considered first, with silver nanoparticles demonstrated to work well as recombination centres for charges from the front and back sub-cells, necessary to avoid a charge build-up at the interface. The growth conditions for the nanoparticles are optimised, with the tandem cells outperforming the single heterojunction architecture. Optical modelling is considered as a method to improve the understanding of thin film solar cells, where interference effects from the reflective aluminium electrode are important in determining the magnitude of absorption a cell can achieve. The use of such modelling is first demonstrated in hybrid solar cells based on a SubPc donor with a titanium oxide (TiOx) acceptor; this system is ideal for observing the effects of interference as only the SubPc layer has significant absorption. The modelling is then applied to tandem cells

  13. Luminescence nanocrystals for solar cell enhancement.

    PubMed

    Liu, Shu-Man; Chen, Wei; Wang, Zhan-Guo

    2010-03-01

    Semiconductor nanocrystals (NCs) prepared by wet-chemical routes have been proposed as an attractive candidate for fabrication of the third-generation thin-film solar cells due to their quantum confinement effects and excellent dispersion ability in polymer films. However, to date, a solar cell incorporating semiconductor NCs in the photoactive layer still has rather low efficiency due to the low carrier mobility of the non-continued NC phase and the possible radiative recombination in NCs. To avoid these disadvantages, NCs have been proposed and applied as a luminescent species in a passive photon converting layer to modify the solar spectrum before the light enters the photovoltaic device. Photon conversion processes, including up-conversion, down-conversion, and down-shifting, have been observed in various colloidal NC samples and have great potential to enhance photovoltaic performance when applied to the existing single-junction solar cells or narrow-band molecular-based devices.

  14. Nanocrystalline silicon based thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ray, Swati

    2012-06-01

    Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

  15. Heat transparent high intensity high efficiency solar cell

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr. (Inventor)

    1982-01-01

    An improved solar cell design is described. A surface of each solar cell has a plurality of grooves. Each groove has a vertical face and a slanted face that is covered by a reflecting metal. Light rays are reflected from the slanted face through the vertical face where they traverse a photovoltaic junction. As the light rays travel to the slanted face of an adjacent groove, they again traverse the junction. The underside of the reflecting coating directs the light rays toward the opposite surface of solar cell as they traverse the junction again. When the light rays travel through the solar cell and reach the saw toothed grooves on the under side, the process of reflection and repeatedly traversing the junction again takes place. The light rays ultimately emerge from the solar cell. These solar cells are particularly useful at very high levels of insolation because the infrared or heat radiation passes through the cells without being appreciably absorbed to heat the cell.

  16. Response of single junction GaAs/GaAs and GaAs/Ge solar cells to multiple doses of 1 MeV electrons

    NASA Technical Reports Server (NTRS)

    Meier, D. L.; Szedon, J. R.; Bartko, J.; Chung, M. A.

    1989-01-01

    A comparison of the radiation tolerance of MOCVD-grown GaAs cells and GaAs/Ge cells was undertaken using 1 MeV electrons. The GaAs/Ge cells are somewhat more tolerant of 1 MeV electron irradiation and more responsive to annealing than are the GaAs/GaAs cells examined in this study. However, both types of cells suffer a greater degradation in efficiency than has been observed in other recent studies. The reason for this is not certain, but it may be associated with an emitter thickness which appears to be greater than desired. The deep level transient spectroscopy (DLTS) spectra following irradiation are not significantly different for the GaAs/Ge and the GaAs/GaAs cells, with each having just two peaks. The annealing behavior of these peaks is also similar in the two samples examined. It appears that no penalty in radiation tolerance, and perhaps some benefit, is associated with fabricating MOCVD GaAs cells on Ge substrates rather than GaAs substrates.

  17. Correcting For Capacitance In Tests Of Solar Cells

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.

    1995-01-01

    Modified procedure for testing solar photovoltaic cells and modified software for processing test data provide corrections for effects of cell capacitance. Procedure and software needed because (a) some photovoltaic devices (for example, silicon solar cells with back-surface field region) store minority charge carriers in cell junction and thus exhibit significant capacitance, (b) capacitance affects current-vs.-voltage (I-V) measurements made when transient load connected to cell, and (c) transient load used in unmodified version of test procedure. Corrected I-V curve obtained in test of solar cell according to modified procedure approximates true cell voltage vs. cell current more closely.

  18. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2014-01-01

    Testing was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by Space Systems Loral, LLC (SSL). The ATJ coupon was a small, 4-cell, two-string configuration of flight-type design that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge (ESD) testing at two string voltages (100 V, 150 V) and four string currents (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micro-seconds to 2.75 milli-seconds. All TSAs occurred at a string voltage of 150 V. Post-ESD functional testing showed that no degradation occurred due to the TSA events. These test results point to a robust design for application to a high-current, high-power mission.

  19. Dye sensitized solar cells.

    PubMed

    Wei, Di

    2010-03-16

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO(2), ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed.

  20. Dye Sensitized Solar Cells

    PubMed Central

    Wei, Di

    2010-01-01

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO2, ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

  1. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  2. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, K. H.; Schneider, T. A.; Vaughn, J. A.; Hoang, B.; Wong, F.

    2014-01-01

    A test was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by SSL. The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge testing at two string voltages (100 V, 150 V) and four array current (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 µs to 2.9 ms. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission application.

  3. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2014-01-01

    Testing was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by Space Systems/Loral, LLC (SSL). The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge (ESD) testing at two string voltages (100 V, 150 V) and four array currents (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micro-seconds to 2.75 milli-seconds. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission.

  4. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2015-01-01

    A test was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by SSL. The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge testing at two string voltages (100 V, 150 V) and four array current (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micros to 2.9 ms. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission application.

  5. 11. 5% solar conversion efficiency in the photocathodically protected p-InP/V/sup 3 +/-V/sup 2 +/-HCI/C semiconductor liquid junction cell

    SciTech Connect

    Heller, A.; Miller, B.; Thiel, F.A.

    1981-02-15

    Oxidation of the surface of p-InP with alkaline peroxide and treatment with dilute potassium cyanide increase the efficiency of the p-InP/V/sup 2 +/-V/sup 3 +/ -HCl/C cell to 11.5%. The open circuit voltage of the cell follows the redox potential of the solution over a 0.5 V range. The lack of voltage pinning is consistent with photoemission studies of Spicer et al., showing that adsorption of oxygen on p-InP raises the surface fermi level from a position near the valence band maximum to noe near the conduction band minimum.

  6. Gallium arsenide solar cell radiation damage study

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

  7. Solar cell array interconnects

    DOEpatents

    Carey, P.G.; Thompson, J.B.; Colella, N.J.; Williams, K.A.

    1995-11-14

    Electrical interconnects are disclosed for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value. 4 figs.

  8. Solar cell array interconnects

    DOEpatents

    Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

    1995-01-01

    Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

  9. Thin silicon solar cells

    SciTech Connect

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M.

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  10. Nanocrystal Solar Cells

    SciTech Connect

    Gur, Ilan

    2006-01-01

    This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.

  11. An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell. Final subcontract report, 1 January 1991--31 August 1992

    SciTech Connect

    Venkatasubramanian, R.

    1993-01-01

    This report describes work to develop inverted-grown Al{sub 0.34}Ga{sub 0.66}As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al{sub 0.34}Ga{sub 0.66}As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The ``cycled`` organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al{sub 0.34}Ga{sub 0.66}As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.

  12. Photoelectrochemical Solar Cells.

    ERIC Educational Resources Information Center

    McDevitt, John T.

    1984-01-01

    This introduction to photoelectrochemical (PEC) cells reviews topics pertaining to solar energy conversion and demonstrates the ease with which a working PEC cell can be prepared with n-type silicon as the photoanode and a platinum counter electrode (both immersed in ethanolic ferrocene/ferricenium solutions). Experiments using the cell are…

  13. Mechanically stacked concentrator tandem solar cells

    NASA Technical Reports Server (NTRS)

    Andreev, V. M.; Rumyantsev, V. D.; Karlina, L. B.; Kazantsev, A. B.; Khvostikov, V. P.; Shvarts, M. Z.; Sorokina, S. V.

    1995-01-01

    Four-terminal mechanically stacked solar cells were developed for advanced space arrays with line-focus reflective concentrators. The top cells are based on AlGaAs/GaAs multilayer heterostructures prepared by low temperature liquid phase epitaxy. The bottom cells are based on heteroepitaxial InP/InGaAs liquid phase epitaxy or on homo-junction GaSb, Zn-diffused structures. The sum of the highest reached efficiencies of the top and bottom cells is 29.4 percent. The best four-terminal tandems have an efficiency of 27 to 28 percent. Solar cells were irradiated with 1 MeV electrons and their performances were determined as a function of fluence up to 10(exp 16) cm(exp-2). It was shown that the radiation resistance of developed tandem cells is similar to the most radiative stable AlGaAs/GaAs cells with a thin p-GaAs photoactive layer.

  14. Welded solar cell interconnection

    NASA Technical Reports Server (NTRS)

    Stofel, E. J.; Browne, E. R.; Meese, R. A.; Vendura, G. J.

    1982-01-01

    The efficiency of the welding of solar-cell interconnects is compared with the efficiency of soldering such interconnects, and the cases in which welding may be superior are examined. Emphasis is placed on ultrasonic welding; attention is given to the solar-cell welding machine, the application of the welding process to different solar-cell configurations, producibility, and long-life performance of welded interconnects. Much of the present work has been directed toward providing increased confidence in the reliability of welding using conditions approximating those that would occur with large-scale array production. It is concluded that there is as yet insufficient data to determine which of three methods (soldering, parallel gap welding, and ultrasonic welding) provides the longest-duration solar panel life.

  15. Screening of solar cells

    NASA Technical Reports Server (NTRS)

    Appelbaum, J.; Chait, A.; Thompson, D. A.

    1993-01-01

    Because solar cells in a production batch are not identical, screening is performed to obtain similar cells for aggregation into arrays. A common technique for screening is based on a single operating point of the I-V characteristic of the cell, usually the maximum power point. As a result, inferior cell matching may occur at the actual operating points. Screening solar cells based on the entire I-V characteristic will inherently result in more similar cells in the array. An array consisting of more similar cells is likely to have better overall characteristics and more predictable performance. Solar cell screening methods and cell ranking are discussed. The concept of a mean cell is defined as a cell 'best' representing all the cells in the production batch. The screening and ranking of all cells are performed with respect to the mean cell. The comparative results of different screening methods are illustrated on a batch of 50 silicon cells of the Space Station Freedom.

  16. Indium Gallium Nitride Multijunction Solar Cell Simulation Using Silvaco Atlas

    DTIC Science & Technology

    2007-06-01

    possibilities of InGaN tandem PV structures”, Solar Energy Materials & Solar Cells, Vol. 87, 595-603, 2004. [6] S. M. Sze, Semiconductor Devices, 2nd edition... ENERGY (EV) TO WAVELENGTH (UM) ..............................................86 D. IV CURVE PLOTS FOR INDIUM GALLIUM NITRIDE QUAD JUNCTION SOLAR... energy on different band gaps (From [15]).....................................19 Figure 13. Simple cubic lattice structure (From [16])......20 Figure

  17. Solar energy conversion in photoelectrochemical cells with semiconductor electrodes

    NASA Astrophysics Data System (ADS)

    Pleskov, Yu. V.

    in recent years the semiconductor/electrolyte interface has been attracting much attention in connection with the search for effective ways of utilizing solar energy. This review systematizes information on photoelectrochemical cells, both for production of hydrogen by water photoelectrolysis and for electric power generation in “liquid-junction solar cells.” Special attention is given to integral characteristics of photoelectrochemical cells. The main difficulties in practical realization of the conversion process and some possible methods of surmounting them are formulated.

  18. Electrical overstress failure in silicon solar cells

    SciTech Connect

    Pease, R.L.; Barnum, J.R.; van Lint, V.A.J.; Vulliet, W.V.; Wrobel, T.F.

    1982-11-01

    A solar-cell electrical-overstress-failure model and the results of experimental measurements of threshold pulsed failure currents on four types of silicon solar cells are presented. The transient EMP field surrounding a lightning stroke has been identified as a potential threat to a photovoltaic array, yet failure analysis of solar cells in a pulsed environment had not previously been reported. Failure in the low-resistivity concentrator cells at pulse widths between 1 ..mu..s and 1 ms occurred initially in the junction. Finger damage in the form of silver melting occurs at currents only slightly greater than that required for junction damage. The result of reverse-bias transient-overstress tests on high-resistivity (10 ..cap omega..cm) cells demonstrated that the predominant failure mode was due to edge currents. These flat-plate cells failed at currents of only 4 to 20 A, which is one or two orders of magnitude below the model predictions. It thus appears that high-resistivity flat-plate cells are quite vulnerable to electrical overstress which could be produced by a variety of mechanisms.

  19. Method of making quasi-grain boundary-free polycrystalline solar cell structure and solar cell structure obtained thereby

    DOEpatents

    Gonzalez, Franklin N.; Neugroschel, Arnost

    1984-02-14

    A new solar cell structure is provided which will increase the efficiency of polycrystalline solar cells by suppressing or completely eliminating the recombination losses due to the presence of grain boundaries. This is achieved by avoiding the formation of the p-n junction (or other types of junctions) in the grain boundaries and by eliminating the grain boundaries from the active area of the cell. This basic concept can be applied to any polycrystalline material; however, it will be most beneficial for cost-effective materials having small grains, including thin film materials.

  20. Solution-processed small-molecule solar cells: breaking the 10% power conversion efficiency.

    PubMed

    Liu, Yongsheng; Chen, Chun-Chao; Hong, Ziruo; Gao, Jing; Yang, Yang Michael; Zhou, Huanping; Dou, Letian; Li, Gang; Yang, Yang

    2013-11-28

    A two-dimensional conjugated small molecule (SMPV1) was designed and synthesized for high performance solution-processed organic solar cells. This study explores the photovoltaic properties of this molecule as a donor, with a fullerene derivative as an acceptor, using solution processing in single junction and double junction tandem solar cells. The single junction solar cells based on SMPV1 exhibited a certified power conversion efficiency of 8.02% under AM 1.5 G irradiation (100 mW cm(-2)). A homo-tandem solar cell based on SMPV1 was constructed with a novel interlayer (or tunnel junction) consisting of bilayer conjugated polyelectrolyte, demonstrating an unprecedented PCE of 10.1%. These results strongly suggest solution-processed small molecular materials are excellent candidates for organic solar cells.

  1. Spectral response measurements of multijunction solar cells with low shunt resistance and breakdown voltages.

    PubMed

    Babaro, Juan P; West, Kevin G; Hamadani, Behrang H

    2016-11-01

    Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage. The analysis revealed that both low shunt resistance and low breakdown voltages in two of the three junctions influenced the measured quantum efficiency of all three junctions. The data and the modeling suggest that combination of current-voltage measurements under various light bias sources can reveal important information about the spectral response behavior in multijunction solar cells.

  2. Four-cell solar tracker

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M.

    1981-01-01

    Forty cm Sun tracker, consisting of optical telescope and four solar cells, stays pointed at Sun throughout day for maximum energy collection. Each solar cell generates voltage proportional to part of solar image it receives; voltages drive servomotors that keep image centered. Mirrored portion of cylinder extends acquisition angle of device by reflecting Sun image back onto solar cells.

  3. Effect of copper impurity on polycrystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Koliwad, K. M.

    1978-01-01

    The presence of copper impurity, up to 10 to the 15th atoms/cc, in single crystal silicon has been shown to have no deleterious effect on the p-n junction solar cell performance. However, in polycrystalline silicon, copper atoms tend to migrate to the defect sites because of the structural sensitive properties of copper. This study was undertaken to investigate the influence of this behavior of copper impurity on the performance of p-n junction solar cells fabricated from structurally imperfect silicon. Two sets of polycrystalline silicon substrates containing copper were examined. In one set of samples, copper was incorporated during growth, whereas in the other, copper was diffused. Solar cells were fabricated on both the sets of substrates by a standard process. Dark and light I-V and spectral response characteristics of the cells were measured and compared with copper-free polycrystalline silicon solar cells. The results and the model are discussed.

  4. Chapter 10: CPV Multijunction Solar Cell Characterization

    SciTech Connect

    Osterwald, Carl R.; Siefer, Gerald

    2016-04-15

    Characterization of solar cells can be divided into two types: the first is measurement of electrooptical semiconductor device parameters, and the second is determination of electrical conversion efficiency. This chapter reviews the multijunction concepts that are necessary for understanding Concentrator photovoltaic (CPV) cell characterization techniques, and describes how CPV efficiency is defined and used. For any I-V measurement of a multijunction cell, the sun simulator spectrum has to be adjusted in a way that all junctions generate the same photocurrent ratios with respect to each other as under reference conditions. The chapter discusses several procedures for spectral irradiance adjustments of solar simulators, essential for multijunction measurements. It overviews the light sources and optics commonly used in simulators for CPV cells under concentration. Finally, the chapter talks about the cell area, quantum efficiency (QE), and current-voltage (I-V) curve measurements that are needed to characterize cells as a function of irradiance.

  5. Generalized Optoelectronic Model of Series-Connected Multijunction Solar Cells

    SciTech Connect

    Geisz, John F.; Steiner, Myles A.; Garcia, Ivan; France, Ryan M.; McMahon, William E.; Osterwald, Carl R.; Friedman, Daniel J.

    2015-10-02

    The emission of light from each junction in a series-connected multijunction solar cell, we found, both complicates and elucidates the understanding of its performance under arbitrary conditions. Bringing together many recent advances in this understanding, we present a general 1-D model to describe luminescent coupling that arises from both voltage-driven electroluminescence and voltage-independent photoluminescence in nonideal junctions that include effects such as Sah-Noyce-Shockley (SNS) recombination with n ≠ 2, Auger recombination, shunt resistance, reverse-bias breakdown, series resistance, and significant dark area losses. The individual junction voltages and currents are experimentally determined from measured optical and electrical inputs and outputs of the device within the context of the model to fit parameters that describe the devices performance under arbitrary input conditions. Furthermore, our techniques to experimentally fit the model are demonstrated for a four-junction inverted metamorphic solar cell, and the predictions of the model are compared with concentrator flash measurements.

  6. Memory cell operation based on small Josephson junctions arrays

    NASA Astrophysics Data System (ADS)

    Braiman, Y.; Nair, N.; Rezac, J.; Imam, N.

    2016-12-01

    In this paper we analyze a cryogenic memory cell circuit based on a small coupled array of Josephson junctions. All the basic memory operations (e.g., write, read, and reset) are implemented on the same circuit and different junctions in the array can in principle be utilized for these operations. The presented memory operation paradigm is fundamentally different from conventional single quantum flux operation logics (SFQ). As an example, we demonstrate memory operation driven by a SFQ pulse employing an inductively coupled array of three Josephson junctions. We have chosen realistic Josephson junction parameters based on state-of-the-art fabrication capabilities and have calculated access times and access energies for basic memory cell operations. We also implemented an optimization procedure based on the simulated annealing algorithm to calculate the optimized and typical values of access times and access energies.

  7. Enhancing Solar Cell Efficiencies through 1-D Nanostructures

    PubMed Central

    2009-01-01

    The current global energy problem can be attributed to insufficient fossil fuel supplies and excessive greenhouse gas emissions resulting from increasing fossil fuel consumption. The huge demand for clean energy potentially can be met by solar-to-electricity conversions. The large-scale use of solar energy is not occurring due to the high cost and inadequate efficiencies of existing solar cells. Nanostructured materials have offered new opportunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including nanotubes, nanowires, and nanorods, offer significant opportunities to improve efficiencies of solar cells by facilitating photon absorption, electron transport, and electron collection; however, tremendous challenges must be conquered before the large-scale commercialization of such cells. This review specifically focuses on the use of 1-D nanostructures for enhancing solar cell efficiencies. Other nanostructured solar cells or solar cells based on bulk materials are not covered in this review. Major topics addressed include dye-sensitized solar cells, quantum-dot-sensitized solar cells, and p-n junction solar cells.

  8. Quantum well solar cells

    NASA Astrophysics Data System (ADS)

    Barnham, K. W. J.; Ballard, I.; Connolly, J. P.; Ekins-Daukes, N. J.; Kluftinger, B. G.; Nelson, J.; Rohr, C.

    2002-04-01

    This paper reviews the experimental and theoretical studies of quantum well solar cells with an aim of providing the background to the more detailed papers on this subject in these proceedings. It discusses the way quantum wells enhance efficiency in real, lattice matched material systems and fundamental studies of radiative recombination relevant to the question of whether such enhancements are possible in ideal cells. A number of theoretical models for quantum well solar cells (QWSCs) are briefly reviewed and more detail is given of our own group's model of the dark-currents. The temperature and field dependence of QWSCs are all briefly reviewed.

  9. Transparent solar cell module

    NASA Technical Reports Server (NTRS)

    Antonides, G. J.; Dillard, P. A.; Fritz, W. M.; Lott, D. P.

    1979-01-01

    Modified solar cell module uses high transmission glass and adhesives, and heat dissipation to boost power per unit area by 25% (9.84% efficiency based on cell area at 60 C and 100 mW/sq cm flux). Design is suited for automatic production and is potentially more cost effective.

  10. Liquid junction schottky barrier solar cell

    DOEpatents

    Williams, Richard

    1980-01-01

    A mixture of ceric ions (Ce.sup.+4) and cerous ions (Ce.sup.+3) in an aqueous electrolyte solution forms a Schottky barrier at the interface between an active region of silicon and the electrolyte solution. The barrier height obtained for hydrogenated amorphous silicon using the Ce.sup.+4 /Ce.sup.+3 redox couple is about 1.7 eV.

  11. Trial Production and Evaluation of Solar Cells Optimized for Solar Spectrum in Mars Atmosphere

    NASA Astrophysics Data System (ADS)

    Toyota, Hiroyuki; Shimada, Takanobu; Takahashi, Yu; Oyama, Akira; Washio, Hidetoshi

    2014-08-01

    We describe the production and evaluation of a prototype of an inverted metamorphic triple-junction (IMM3J) solar cell optimized for the solar spectrum on the surface of Mars. High-efficiency, flexible, lightweight solar panels containing IMM3J solar cells are promising power sources for Mars surface explorers such as rovers, landers, and airplanes. The intensity of sunlight at the Martian surface substantially decreases at wavelengths shorter than 700 nm because of absorption and scattering by the atmosphere. This decreases the output current of the InGaP top cells in state-of-the-art IMM3J solar cells, and thus decreases the overall output current. Therefore, solar cells for Mars surface explorers need to be optimized for the solar spectrum at the Martian surface. We modified IMM3J solar cells in two ways to increase the output power. We increased the thickness of the InGaP top cell to increase the light absorption, which increased the output current of the entire cell. We also increased the band gap energy of the InGaAs bottom cell by trimming the surplus current, in order to increase the output voltage. In the simulated Martian solar spectrum, the performance of the prototype solar cells was higher than that of IMM3J solar cells designed for the AM0 spectrum.

  12. Parameterization of solar cells

    NASA Technical Reports Server (NTRS)

    Appelbaum, J.; Chait, A.; Thompson, D.

    1992-01-01

    The aggregation (sorting) of the individual solar cells into an array is commonly based on a single operating point on the current-voltage (I-V) characteristic curve. An alternative approach for cell performance prediction and cell screening is provided by modeling the cell using an equivalent electrical circuit, in which the parameters involved are related to the physical phenomena in the device. These analytical models may be represented by a double exponential I-V characteristic with seven parameters, by a double exponential model with five parameters, or by a single exponential equation with four or five parameters. In this article we address issues concerning methodologies for the determination of solar cell parameters based on measured data points of the I-V characteristic, and introduce a procedure for screening of solar cells for arrays. We show that common curve fitting techniques, e.g., least squares, may produce many combinations of parameter values while maintaining a good fit between the fitted and measured I-V characteristics of the cell. Therefore, techniques relying on curve fitting criteria alone cannot be directly used for cell parameterization. We propose a consistent procedure which takes into account the entire set of parameter values for a batch of cells. This procedure is based on a definition of a mean cell representing the batch, and takes into account the relative contribution of each parameter to the overall goodness of fit. The procedure is demonstrated on a batch of 50 silicon cells for Space Station Freedom.

  13. Advanced Solar Cells for Satellite Power Systems

    NASA Technical Reports Server (NTRS)

    Flood, Dennis J.; Weinberg, Irving

    1994-01-01

    The multiple natures of today's space missions with regard to operational lifetime, orbital environment, cost and size of spacecraft, to name just a few, present such a broad range of performance requirements to be met by the solar array that no single design can suffice to meet them all. The result is a demand for development of specialized solar cell types that help to optimize overall satellite performance within a specified cost range for any given space mission. Historically, space solar array performance has been optimized for a given mission by tailoring the features of silicon solar cells to account for the orbital environment and average operating conditions expected during the mission. It has become necessary to turn to entirely new photovoltaic materials and device designs to meet the requirements of future missions, both in the near and far term. This paper will outline some of the mission drivers and resulting performance requirements that must be met by advanced solar cells, and provide an overview of some of the advanced cell technologies under development to meet them. The discussion will include high efficiency, radiation hard single junction cells; monolithic and mechanically stacked multiple bandgap cells; and thin film cells.

  14. Cell accumulation in the junctional region of denervated muscle

    PubMed Central

    1987-01-01

    If skeletal muscles are denervated, the number of mononucleated cells in the connective tissue between muscle fibers increases. Since interstitial cells might remodel extracellular matrix, and since extracellular matrix in nerve and muscle plays a direct role in reinnervation of the sites of the original neuromuscular junctions, we sought to determine whether interstitial cell accumulation differs between junctional and extrajunctional regions of denervated muscle. We found in muscles from frog and rat that the increase in interstitial cell number was severalfold (14-fold for frog, sevenfold for rat) greater in the vicinity of junctional sites than in extrajunctional regions. Characteristics of the response at the junctional sites of frog muscles are as follows. During chronic denervation, the accumulation of interstitial cells begins within 1 wk and it is maximal by 3 wk. Reinnervation 1-2 wk after nerve damage prevents the maximal accumulation. Processes of the cells form a multilayered veil around muscle fibers but make little, if any, contact with the muscle cell or its basal lamina sheath. The results of additional experiments indicate that the accumulated cells do not originate from terminal Schwann cells or from muscle satellite cells. Most likely the cells are derived from fibroblasts that normally occupy the space between muscle fibers and are known to make and degrade extracellular matrix components. PMID:3491825

  15. Progress towards a 30% efficient GaInP/Si tandem solar cells

    DOE PAGES

    Essig, Stephanie; Ward, Scott; Steiner, Myles A.; ...

    2015-08-28

    The performance of dual-junction solar cells with a Si bottom cell has been investigated both theoretically and experimentally. Simulations show that adding a top junction with an energy bandgap of 1.6 -1.9 eV to a standard silicon solar cell enables efficiencies over 38%. Currently, top junctions of GaInP (1.8 eV) are the most promising as they can achieve 1-sun efficiencies of 20.8% [1]. We fabricated mechanically stacked, four terminal GaInP/Si tandem solar cells using a transparent adhesive between the subcells. These tandem devices achieved an efficiency of 27% under AM1.5 g spectral conditions. Furthermore, higher efficiencies can be achieved bymore » using an improved Si-bottom cell and by optimizing the dual-junction device for long-wavelength light and luminescent coupling between the two junctions.« less

  16. Progress towards a 30% efficient GaInP/Si tandem solar cells

    SciTech Connect

    Essig, Stephanie; Ward, Scott; Steiner, Myles A.; Friedman, Daniel J.; Geisz, John F.; Stradins, Paul; Young, David L.

    2015-08-28

    The performance of dual-junction solar cells with a Si bottom cell has been investigated both theoretically and experimentally. Simulations show that adding a top junction with an energy bandgap of 1.6 -1.9 eV to a standard silicon solar cell enables efficiencies over 38%. Currently, top junctions of GaInP (1.8 eV) are the most promising as they can achieve 1-sun efficiencies of 20.8% [1]. We fabricated mechanically stacked, four terminal GaInP/Si tandem solar cells using a transparent adhesive between the subcells. These tandem devices achieved an efficiency of 27% under AM1.5 g spectral conditions. Furthermore, higher efficiencies can be achieved by using an improved Si-bottom cell and by optimizing the dual-junction device for long-wavelength light and luminescent coupling between the two junctions.

  17. A simple theory of back surface field /BSF/ solar cells

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1978-01-01

    A theory of an n-p-p/+/ junction is developed, entirely based on Shockley's depletion layer approximation. Under the further assumption of uniform doping the electrical characteristics of solar cells as a function of all relevant parameters (cell thickness, diffusion lengths, etc.) can quickly be ascertained with a minimum of computer time. Two effects contribute to the superior performance of a BSF cell (n-p-p/+/ junction) as compared to an ordinary solar cell (n-p junction). The sharing of the applied voltage among the two junctions (the n-p and the p-p/+/ junction) decreases the dark current and the reflection of minority carriers by the builtin electron field of the p-p/+/ junction increases the short-circuit current. The theory predicts an increase in the open-circuit voltage (Voc) with a decrease in cell thickness. Although the short-circuit current decreases at the same time, the efficiency of the cell is virtually unaltered in going from a thickness of 200 microns to a thickness of 50 microns. The importance of this fact for space missions where large power-to-weight ratios are required is obvious.

  18. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Carter, J. R., Jr.; Tada, H. Y.

    1973-01-01

    A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

  19. Monolithic tandem solar cell

    DOEpatents

    Wanlass, Mark W.

    1991-01-01

    A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surface of the InP substrate, and (c) a second photoactive subcell on the first subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched. The solar cell can be provided as a two-terminal device or a three-terminal device.

  20. Flexible Solar Cells

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Solar cell "modules" are plastic strips coated with thin films of photovoltaic silicon that collect solar energy for instant conversion into electricity. Lasers divide the thin film coating into smaller cells to build up voltage. Developed by Iowa Thin Film Technologies under NASA and DOE grants, the modules are used as electrical supply for advertising displays, battery rechargers for recreational vehicles, and to power model airplanes. The company is planning other applications both in consumer goods and as a power source in underdeveloped countries.

  1. Determination of series resistance of indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving

    1991-01-01

    The series resistance of a solar cell is an important parameter, which must be minimized to achieve high cell efficiencies. The cell series resistance is affected by the starting material, its design, and processing. The theoretical approach proposed by Jia, et. al., is used to calculate the series resistance of indium phosphide solar cells. It is observed that the theoretical approach does not predict the series resistance correctly in all cases. The analysis was modified to include the use of effective junction ideality factor. The calculated results were compared with the available experimental results on indium phosphide solar cells processed by different techniques. It is found that the use of process dependent junction ideality factor leads to better estimation of series resistance. An accurate comprehensive series resistance model is warranted to give proper feedback for modifying the cell processing from the design state.

  2. Solar cells: Operating principles, technology, and system applications

    NASA Astrophysics Data System (ADS)

    Green, M. A.

    Solar cell theory, materials, fabrication, design, modules, and systems are discussed. The solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics. Particular attention is given to p-n junction diodes, including efficiency limits, losses, and measurements. Si solar cell technology is described for the production of solar-quality crystals and wafers, and design, improvements, and device structures are examined. Consideration is given to alternate semiconductor materials and applications in concentrating systems, storage, and the design and construction of stand-alone systems and systems for residential and centralized power generation.

  3. TJ Solar Cell

    SciTech Connect

    Friedman, Daniel

    2009-04-17

    This talk will discuss recent developments in III-V multijunction photovoltaic technology which have led to the highest-efficiency solar cells ever demonstrated. The relationship between the materials science of III-V semiconductors and the achievement of record solar cell efficiencies will be emphasized. For instance, epitaxially-grown GAInP has been found to form a spontaneously-ordered GaP/InP (111) superlattice. This ordering affects the band gap of the material, which in turn affects the design of solar cells which incorporate GaInP. For the next generation of ultrahigh-efficiency III-V solar cells, we need a new semiconductor which is lattice-matched to GaAs, has a band gap of 1 eV, and has long minority-carrier diffusion lengths. Out of a number of candidate materials, the recently-discovered alloy GaInNAs appears to have the greatest promise. This material satisfies the first two criteria, but has to date shown very low diffusion lengths, a problem which is our current focus in the development of these next-generation cells.

  4. New approaches for high-efficiency solar cells. Final report

    SciTech Connect

    Bedair, S M; El-Masry, N A

    1997-12-01

    This report summarizes the activities carried out in this subcontract. These activities cover, first the atomic layer epitaxy (ALE) growth of GaAs, AlGaAs and InGaP at fairly low growth temperatures. This was followed by using ALE to achieve high levels of doping both n-type and p-type required for tunnel junctions (Tj) in the cascade solar cell structures. Then the authors studied the properties of AlGaAs/InGaP and AlGaAs/GaAs tunnel junctions and their performances at different growth conditions. This is followed by the use of these tunnel junctions in stacked solar cell structures. The effect of these tunnel junctions on the performance of stacked solar cells was studied at different temperatures and different solar fluences. Finally, the authors studied the effect of different types of black surface fields (BSF), both p/n and n/p GaInP solar cell structures, and their potential for window layer applications. Parts of these activities were carried in close cooperation with Dr. Mike Timmons of the Research Triangle Institute.

  5. Making Ultrathin Solar Cells

    NASA Technical Reports Server (NTRS)

    Cogan, George W.; Christel, Lee A.; Merchant, J. Thomas; Gibbons, James F.

    1991-01-01

    Process produces extremely thin silicon solar cells - only 50 micrometers or less in thickness. Electrons and holes have less opportunity to recombine before collected at cell surfaces. Efficiency higher and because volume of silicon small, less chance of radiation damage in new cells. Initial steps carried out at normal thickness to reduce breakage and avoid extra cost of special handling. Cells then thinned mechanically and chemically. Final cell includes reflective layer on back surface. Layer bounces unabsorbed light back into bulk silicon so it absorbs and produces useful electrical output.

  6. Metamorphic III–V Solar Cells: Recent Progress and Potential

    SciTech Connect

    Garcia, Ivan; France, Ryan M.; Geisz, John F.; McMahon, William E.; Steiner, Myles A.; Johnston, Steve; Friedman, Daniel J.

    2016-01-01

    Inverted metamorphic multijunction solar cells have been demonstrated to be a pathway to achieve the highest photovoltaic (PV) conversion efficiencies. Attaining high-quality lattice-mismatched (metamorphic) semiconductor devices is challenging. However, recent improvements to compositionally graded buffer epitaxy and junction structures have led to the achievement of high-quality metamorphic solar cells exhibiting internal luminescence efficiencies over 90%. For this high material quality, photon recycling is significant, and therefore, the optical environment of the solar cell becomes important. In this paper, we first present recent progress and performance results for 1- and 0.7-eV GaInAs solar cells grown on GaAs substrates. Then, an electrooptical model is used to assess the potential performance improvements in current metamorphic solar cells under different realizable design scenarios. The results show that the quality of 1-eV subcells is such that further improving its electronic quality does not produce significant Voc increases in the four-junction inverted metamorphic subcells, unless a back reflector is used to enhance photon recycling, which would significantly complicate the structure. Conversely, improving the electronic quality of the 0.7-eV subcell would lead to significant Voc boosts, driving the progress of four-junction inverted metamorphic solar cells.

  7. Inversion layer solar cell fabrication and evaluation

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1974-01-01

    Inversion layer solar cells have been fabricated by etching through the diffused layer on p-type silicon wafers in a comb-like contact pattern. The charge separation comes from an induced p-n junction at the surface. This inverted surface is caused by a layer of transparent material applied to the surface that either contains free positive ions or that creates donor states at the interface. Cells have increased from 3 ma Isc to 100 ma by application of sodium silicate. The action is unstable, however, and decays with time.

  8. Inversion layer solar cell fabrication and evaluation. [measurement of response of inversion layer solar cell to light of different wavelengths

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1973-01-01

    Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. This charged layer was supplied through three mechanisms: (1) applying a positive potential to a transparent electrode separated from the silicon surface by a dielectric, (2) contaminating the oxide layer with positive ions, and (3) forming donor surface states that leave a positive charge on the surface. A movable semi-infinite shadow delineated the extent of sensitivity of the cell due to the inversion region. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

  9. Multiple junction cell characterization using the LBIC method : early results, issues, and pathways to improvement.

    SciTech Connect

    Finn, Jason R.; Granata, Jennifer E.; Hansen, Barry R.

    2010-03-01

    A light beam induced current (LBIC) measurement is a non-destructive technique that produces a spatial graphical representation of current response in photovoltaic cells with respect to position when stimulated by a light beam. Generally, a laser beam is used for these measurements because the spot size can be made very small, on the order of microns, and very precise measurements can be made. Sandia National Laboratories Photovoltaic System Evaluation Laboratory (PSEL) uses its LBIC measurement technique to characterize single junction mono-crystalline and multi-crystalline solar cells ranging from miniature to conventional sizes. Sandia has modified the already valuable LBIC technique to enable multi-junction PV cells to be characterized.

  10. NASA Facts, Solar Cells.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    The design and function of solar cells as a source of electrical power for unmanned space vehicles is described in this pamphlet written for high school physical science students. The pamphlet is one of the NASA Facts Science Series (each of which consists of four pages) and is designed to fit in the standard size three-ring notebook. Review…

  11. Nanoimprinted polymer solar cell.

    PubMed

    Yang, Yi; Mielczarek, Kamil; Aryal, Mukti; Zakhidov, Anvar; Hu, Walter

    2012-04-24

    Among the various organic photovoltaic devices, the conjugated polymer/fullerene approach has drawn the most research interest. The performance of these types of solar cells is greatly determined by the nanoscale morphology of the two components (donor/acceptor) and the molecular orientation/crystallinity in the photoactive layer. A vertically bicontinuous and interdigitized heterojunction between donor and acceptor has been regarded as one of the ideal structures to enable both efficient charge separation and transport. Synergistic control of polymer orientation in the nanostructured heterojunction is also critical to improve the performance of polymer solar cells. Nanoimprint lithography has emerged as a new approach to simultaneously control both the heterojunction morphology and polymer chains in organic photovoltaics. Currently, in the area of nanoimprinted polymer solar cells, much progress has been achieved in the fabrication of nanostructured morphology, control of molecular orientation/crystallinity, deposition of acceptor materials, patterned electrodes, understanding of structure-property correlations, and device performance. This review article summarizes the recent studies on nanoimprinted polymer solar cells and discusses the outstanding challenges and opportunities for future work.

  12. Treponema pallidum Invades Intercellular Junctions of Endothelial Cell Monolayers

    NASA Astrophysics Data System (ADS)

    Thomas, D. Denee; Navab, Mahamad; Haake, David A.; Fogelman, Alan M.; Miller, James N.; Lovett, Michael A.

    1988-05-01

    The pathogenesis of syphilis reflects invasive properties of Treponema pallidum, but the actual mode of tissue invasion is unknown. We have found two in vitro parallels of treponemal invasiveness. We tested whether motile T. pallidum could invade host cells by determining the fate of radiolabeled motile organisms added to a HeLa cell monolayer; 26% of treponemes associated with the monolayer in a trypsin-resistant niche, presumably between the monolayer and the surface to which it adhered, but did not attain intracellularity. Attachment of T. pallidum to cultured human and rabbit aortic and human umbilical vein endothelial cells was 2-fold greater than to HeLa cells. We added T. pallidum to aortic endothelial cells grown on membrane filters under conditions in which tight intercellular junctions had formed. T. pallidum was able to pass through the endothelial cell monolayers without altering tight junctions, as measured by electrical resistance. In contrast, heat-killed T. pallidum and the nonpathogen Treponema phagedenis biotype Reiter failed to penetrate the monolayer. Transmission electron micrographs of sections of the monolayer showed T. pallidum in intercellular junctions. Our in vitro observations suggest that these highly motile spirochetes may leave the circulation by invading the junctions between endothelial cells.

  13. Metal-Insulator-Semiconductor Nanowire Network Solar Cells.

    PubMed

    Oener, Sebastian Z; van de Groep, Jorik; Macco, Bart; Bronsveld, Paula C P; Kessels, W M M; Polman, Albert; Garnett, Erik C

    2016-06-08

    Metal-insulator-semiconductor (MIS) junctions provide the charge separating properties of Schottky junctions while circumventing the direct and detrimental contact of the metal with the semiconductor. A passivating and tunnel dielectric is used as a separation layer to reduce carrier recombination and remove Fermi level pinning. When applied to solar cells, these junctions result in two main advantages over traditional p-n-junction solar cells: a highly simplified fabrication process and excellent passivation properties and hence high open-circuit voltages. However, one major drawback of metal-insulator-semiconductor solar cells is that a continuous metal layer is needed to form a junction at the surface of the silicon, which decreases the optical transmittance and hence short-circuit current density. The decrease of transmittance with increasing metal coverage, however, can be overcome by nanoscale structures. Nanowire networks exhibit precisely the properties that are required for MIS solar cells: closely spaced and conductive metal wires to induce an inversion layer for homogeneous charge carrier extraction and simultaneously a high optical transparency. We experimentally demonstrate the nanowire MIS concept by using it to make silicon solar cells with a measured energy conversion efficiency of 7% (∼11% after correction), an effective open-circuit voltage (Voc) of 560 mV and estimated short-circuit current density (Jsc) of 33 mA/cm(2). Furthermore, we show that the metal nanowire network can serve additionally as an etch mask to pattern inverted nanopyramids, decreasing the reflectivity substantially from 36% to ∼4%. Our extensive analysis points out a path toward nanowire based MIS solar cells that exhibit both high Voc and Jsc values.

  14. ZO-1 controls endothelial adherens junctions, cell-cell tension, angiogenesis, and barrier formation.

    PubMed

    Tornavaca, Olga; Chia, Minghao; Dufton, Neil; Almagro, Lourdes Osuna; Conway, Daniel E; Randi, Anna M; Schwartz, Martin A; Matter, Karl; Balda, Maria S

    2015-03-16

    Intercellular junctions are crucial for mechanotransduction, but whether tight junctions contribute to the regulation of cell-cell tension and adherens junctions is unknown. Here, we demonstrate that the tight junction protein ZO-1 regulates tension acting on VE-cadherin-based adherens junctions, cell migration, and barrier formation of primary endothelial cells, as well as angiogenesis in vitro and in vivo. ZO-1 depletion led to tight junction disruption, redistribution of active myosin II from junctions to stress fibers, reduced tension on VE-cadherin and loss of junctional mechanotransducers such as vinculin and PAK2, and induced vinculin dissociation from the α-catenin-VE-cadherin complex. Claudin-5 depletion only mimicked ZO-1 effects on barrier formation, whereas the effects on mechanotransducers were rescued by inhibition of ROCK and phenocopied by JAM-A, JACOP, or p114RhoGEF down-regulation. ZO-1 was required for junctional recruitment of JACOP, which, in turn, recruited p114RhoGEF. ZO-1 is thus a central regulator of VE-cadherin-dependent endothelial junctions that orchestrates the spatial actomyosin organization, tuning cell-cell tension, migration, angiogenesis, and barrier formation.

  15. Space solar cell technology development - A perspective

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J.

    1982-01-01

    The developmental history of photovoltaics is examined as a basis for predicting further advances to the year 2000. Transistor technology was the precursor of solar cell development. Terrestrial cells were modified for space through changes in geometry and size, as well as the use of Ag-Ti contacts and manufacture of a p-type base. The violet cell was produced for Comsat, and involved shallow junctions, new contacts, and an enhanced antireflection coating for better radiation tolerance. The driving force was the desire by private companies to reduce cost and weight for commercial satellite power supplies. Liquid phase epitaxial (LPE) GaAs cells are the latest advancement, having a 4 sq cm area and increased efficiency. GaAs cells are expected to be flight ready in the 1980s. Testing is still necessary to verify production techniques and the resistance to electron and photon damage. Research will continue in CVD cell technology, new panel technology, and ultrathin Si cells.

  16. Diagnostics of Forward Biased Silicon Solar Cells Using Noise Spectroscopy

    NASA Astrophysics Data System (ADS)

    Macku, R.; Koktavy, P.; Skarvada, P.; Raska, M.; Sadovsky, P.

    2009-04-01

    Our research is above all focused on non-destructive testing of the solar cells. We study a single-crystal silicon solar cells n+p and we don't have serious information about features of a pn junction and impurities distribution. The main point of our study is characterization of the local defects in samples. These defects lead to live-time reduction and degradation of reliability. Flicker noise in forward biased solar cells is subject of this paper. We will discuss our measurement with Kleinpenning approaches for inhomogeneous semiconductors and we suggest the physical nature of the samples behaviour.

  17. Testicular cell junction: a novel target for male contraception.

    PubMed

    Lee, Nikki P Y; Wong, Elissa W P; Mruk, Dolores D; Cheng, C Yan

    2009-01-01

    Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

  18. Single P-N junction tandem photovoltaic device

    DOEpatents

    Walukiewicz, Wladyslaw; Ager, III, Joel W.; Yu, Kin Man

    2011-10-18

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  19. Single P-N junction tandem photovoltaic device

    DOEpatents

    Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

    2012-03-06

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  20. Diffusion lengths in amphoteric GaAs heteroface solar cells

    NASA Technical Reports Server (NTRS)

    Ashley, K. L.; Beal, S. W.

    1978-01-01

    Minority-carrier diffusion lengths in amphoteric GaAs:Si were investigated. Electron and hole diffusion lengths in p- and n-type, respectively, were determined to be 13 microns and 7 microns. Preliminary efficiency measurements on heteroface structures based on amphoteric GaAs:Si p-n junctions indicated that these devices should make excellent solar cells.

  1. High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

    SciTech Connect

    Uzu, Hisashi E-mail: npark@skku.edu; Ichikawa, Mitsuru; Hino, Masashi; Nakano, Kunihiro; Meguro, Tomomi; Yamamoto, Kenji; Hernández, José Luis; Kim, Hui-Seon; Park, Nam-Gyu E-mail: npark@skku.edu

    2015-01-05

    We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cell or a CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.

  2. EDITORIAL: Nanostructured solar cells Nanostructured solar cells

    NASA Astrophysics Data System (ADS)

    Greenham, Neil C.; Grätzel, Michael

    2008-10-01

    Conversion into electrical power of even a small fraction of the solar radiation incident on the Earth's surface has the potential to satisfy the world's energy demands without generating CO2 emissions. Current photovoltaic technology is not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be underestimated, a major bottleneck lies in the photovoltaic devices themselves. Improving efficiency is part of the solution, but diminishing returns in that area mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes. Solution-processible materials, e.g. organic molecules, conjugated polymers and semiconductor nanoparticles, offer new routes to the low-cost production of solar cells. The challenge here is that absorbing light in an organic material produces a coulombically bound exciton that requires dissociation at a donor-acceptor heterojunction. A thickness of at least 100 nm is required to absorb the incident light, but excitons only diffuse a few nanometres before decaying. The problem is therefore intrinsically at the nano-scale: we need composite devices with a large area of internal donor-acceptor interface, but where each carrier has a pathway to the respective electrode. Dye-sensitized and bulk heterojunction cells have nanostructures which approach this challenge in different ways, and leading research in this area is described in many of the articles in this special issue. This issue is not restricted to organic or dye-sensitized photovoltaics, since nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at

  3. AlGaAs-GaAs cascade solar cell

    NASA Technical Reports Server (NTRS)

    Lamorte, M. F.; Abbott, D. H.

    1980-01-01

    Computer modeling studies are reported for a monolithic, two junction, cascade solar cell using the AlGaAs GaAs materials combination. An optimum design was obtained through a serial optimization procedure by which conversion efficiency is maximized for operation at 300 K, AM 0, and unity solar concentration. Under these conditions the upper limit on efficiency was shown to be in excess of 29 percent, provided surface recombination velocity did not exceed 10,000 cm/sec.

  4. Iron-copper metallization for flexible solar/cell arrays

    NASA Technical Reports Server (NTRS)

    Lavendel, H. W.

    1983-01-01

    The feasibility of a copper-base metallization for shallow-junction cells applied in flexible solar arrays in space is discussed. This type of metallization will reduce usage of precious metals (such as silver), increase case of bonding (by welding or by soldering) and eliminate heavy high Z interconnects (such as molybdenum). The main points of concern are stability against thermally induced diffusion of copper into silicon which causes degradation of shallow cell junctions, and low series resistance of the contact with semiconductor which promotes cell efficiency.

  5. Quantum Dot Solar Cells

    NASA Technical Reports Server (NTRS)

    Raffaelle, Ryne P.; Castro, Stephanie L.; Hepp, Aloysius; Bailey, Sheila G.

    2002-01-01

    We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

  6. Dilute Group III-V nitride intermediate band solar cells with contact blocking layers

    DOEpatents

    Walukiewicz, Wladyslaw [Kensington, CA; Yu, Kin Man [Lafayette, CA

    2012-07-31

    An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

  7. Dilute group III-V nitride intermediate band solar cells with contact blocking layers

    DOEpatents

    Walukiewicz, Wladyslaw; Yu, Kin Man

    2015-02-24

    An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

  8. Large area low-cost space solar cell development

    NASA Technical Reports Server (NTRS)

    Barona, C. R.; Cioni, J. L.

    1982-01-01

    A development program to produce 5.9 x 5.9 cm space quality silicon solar cells with a cost goal of 30 $/W is described. Cell types investigated include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm/cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover glass simultaneously is being developed. Results for cell and array tests are given. Large solar arrays that might use cells of this type are discussed.

  9. The Membrane Junctions in Communicating and Noncommunicating Cells, Their Hybrids, and Segregants

    PubMed Central

    Azarnia, R.; Larsen, W. J.; Loewenstein, W. R.

    1974-01-01

    Human Lesch-Nyhan cells, which are coupling and have gap junctions, were fused with mouse cl-lD cells, which are noncoupling and lack gap junctions. The resulting hybrid cells were coupling and had gap junctions while they contained the nearly complete complement of parent chromosomes. As the hybrid cells lost human chromosomes, clones appeared among the segregants, which had reverted to the noncoupling and junction-deficient trait of the mouse parent cell. The human cell appears to contribute a genetic factor to the hybrids that corrects the junctional deficiency of the mouse cell. Images PMID:4522798

  10. Tandem junction amorphous semiconductor photovoltaic cell

    DOEpatents

    Dalal, Vikram L.

    1983-01-01

    A photovoltaic stack comprising at least two p.sup.+ i n.sup.+ cells in optical series, said cells separated by a transparent ohmic contact layer(s), provides a long optical path for the absorption of photons while preserving the advantageous field-enhanced minority carrier collection arrangement characteristic of p.sup.+ i n.sup.+ cells.

  11. Tandem junction amorphous semiconductor photovoltaic cell

    DOEpatents

    Dalal, V.L.

    1983-06-07

    A photovoltaic stack comprising at least two p[sup +]i n[sup +] cells in optical series, said cells separated by a transparent ohmic contact layer(s), provides a long optical path for the absorption of photons while preserving the advantageous field-enhanced minority carrier collection arrangement characteristic of p[sup +]i n[sup +] cells. 3 figs.

  12. A photoelectrochemical-thermal hydrogen producing cycle involving a semiconductor liquid junction cell

    NASA Astrophysics Data System (ADS)

    Gissler, W.

    A photoelectrochemical-thermal hydrogen producing cycle is proposed involving a semiconductor liquid junction solar cell. In contrast with direct photoelectrolysis, the proposal is based upon a photoelectrochemical oxidation or reduction of the n- or p-type semiconductor electrode respectively in an aqueous electrolyte. In subsequent thermal reaction steps the water splitting process is completed, and the semiconductor electrode is regenerated. The advantage of the method is that semiconductors of band gap energies which are well matched to the solar spectrum can be used and correspondingly high solar energy conversion efficiencies can be obtained. The drawback is that the electrode regeneration process is in general quite complicated. The method is demonstrated by using a trigonal selenium electrode which allows a relatively simple regeneration. First experimental results on the photoelectrochemical reaction step are reported.

  13. Solar-Cell String Conveyor

    NASA Technical Reports Server (NTRS)

    Frasch, W.; Ciavola, S.

    1982-01-01

    String-conveyor portion of solar-array assembly line holds silicon solar cells while assembled into strings and tested. Cells are transported collector-side-down, while uniform cell spacing and registration are maintained. Microprocessor on machine controls indexing of cells.

  14. Assembling solar-cell arrays

    NASA Technical Reports Server (NTRS)

    Bloch, J. T.; Hanger, R. T.; Nichols, F. W.

    1979-01-01

    Modified 70 mm movie film editor automatically attaches solar cells to flexible film substrate. Machine can rapidly and inexpensively assemble cells for solar panels at rate of 250 cells per minute. Further development is expected to boost production rate to 1000 cells per minute.

  15. A 31%-efficient GaAs/silicon mechanically stacked, multijunction concentrator solar cell

    SciTech Connect

    Gee, J.M.; Virshup, G.F.

    1988-01-01

    Development and demonstration of a GaAs/silicon mechanically stacked, multi-junction (MSMJ) solar concentrator cell with an efficiency in excess of 30% is reported. This is the highest efficiency ever reported for a solar cell and this is the first solar cell to ever achieve an efficiency in excess of 30%. Our preliminary analysis suggests that an efficiency approaching 35% is possible with GaAs-based MSMJ cells. (22 refs., 2 tabs.)

  16. A theoretical analysis of the current-voltage characteristics of solar cells

    NASA Technical Reports Server (NTRS)

    Hauser, J. R.; Dunbar, P. M.

    1974-01-01

    The current-voltage characteristics and efficiencies of solar cells are discussed. For one solar cell structure detailed curves are presented which include carrier densities, current densities, potential, and quasi-Fermi levels at different voltage levels both with and without optically generated carriers (AMO conditions). In addition some results are presented concerning the influence of various parameter variations such as lifetime, cell thickness, and high-low junction width on solar cell performance.

  17. Silicon sheet with molecular beam epitaxy for high efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Allen, F. G.

    1983-01-01

    The capabilities of the new technique of Molecular Beam Epitaxy (MBE) are applied to the growth of high efficiency silicon solar cells. Because MBE can provide well controlled doping profiles of any desired arbitrary design, including doping profiles of such complexity as built-in surface fields or tandem junction cells, it would appear to be the ideal method for development of high efficiency solar cells. It was proposed that UCLA grow and characterize silicon films and p-n junctions of MBE to determine whether the high crystal quality needed for solar cells could be achieved.

  18. Studies of Sputtered Cadmium Telluride and Cadmium Selenide Solar Cells

    NASA Astrophysics Data System (ADS)

    Kwon, Dohyoung

    CdTe has recently become the most commercially successful polycrystalline thinfilm solar module material. Its low cost, large-area solar module is reshaping the silicondominated solar panel market; however, CdTe has much room to improve and thus more fundamental understanding is needed. Current thin film solar cell research is focused on two areas: One is identifying loss mechanisms and understanding the polycrystalline nature of single junction device to improve device performance. Another is searching for new materials and fabricating tandem solar cells. In this study, along with other people's work to improve the efficiency of CdTe solar module, I studied loss mechanism and growth mode of CdTe solar cells to have fundamental understanding of polycrystalline films. In addition to that, in an effort to make tandem solar cells, I fabricated and characterized CdSe solar cells, which is considered as an ideal candidate for the top cell with its band gap of 1.7 eV. This dissertation is designed to show similarities and differences between CdTe and CdSe solar cells, side by side. After the introduction (Chapter1), I will review the physical properties of CdTe and CdSe solar cells (Chapter 2). Two primary tools to study defects and surface morphology were photoluminescence (PL) and atomic force microscopy (AFM). PL showed information on the crystallinity and defects of CdTe and CdSe films before and after annealing.(Chapter 3). AFM measurements and their analysis using scaling theory revealed information on the growth modes of CdTe and CdSe films.(Chapter 4). With the goal of exploring suitability for tandem structures with ˜1.7 eV top cell and ˜1.1 eV bottom cell, I fabricated and characterized single-junction CdSe devices. (Chapter 5) In addition, for the bottom cell I fabricated HgCdTe cells with Eg˜1.1 eV. Single junction HgCdTe and two-terminal CdTe/HgCdTe tandem solar cells were fabricated and characterized. (Chapter 5)

  19. Gap Junctional Regulation of Signal Transduction in Bone Cells

    PubMed Central

    Buo, Atum M.; Stains, Joseph P.

    2014-01-01

    The role of gap junctions, particularly that of connexin43 (Cx43), has become an area of increasing interest in bone physiology. An abundance of studies have shown that Cx43 influences the function of osteoblasts and osteocytes, which ultimately impacts bone mass acquisition and skeletal homeostasis. However, the molecular details underlying how Cx43 regulates bone are only coming into focus and have proven to be more complex than originally thought. In this review, we focus on the diverse molecular mechanisms by which Cx43 gap junctions and hemichannels regulate cell signaling pathways, gene expression, mechanotransduction and cell survival in bone cells. This review will highlight key signaling factors that have been identified as downstream effectors of Cx43 and the impact of these pathways on distinct osteoblast and osteocyte functions. PMID:24486014

  20. Plastic Schottky barrier solar cells

    DOEpatents

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.