Science.gov

Sample records for improving solar cell

  1. Plasma Etching Improves Solar Cells

    NASA Technical Reports Server (NTRS)

    Bunyan, S. M.

    1982-01-01

    Etching front surfaces of screen-printed silicon photovoltaic cells with sulfur hexafluoride plasma found to increase cell performance while maintaining integrity of screen-printed silver contacts. Replacement of evaporated-metal contacts with screen-printed metal contacts proposed as one way to reduce cost of solar cells for terrestrial applications.

  2. Solar Cell Modules With Improved Backskin

    DOEpatents

    Gonsiorawski, Ronald C.

    2003-12-09

    A laminated solar cell module comprises a front light transmitting support, a plurality of interconnected solar cells encapsulated by a light-transmitting encapsulant material, and an improved backskin formed of an ionomer/nylon alloy. The improved backskin has a toughness and melting point temperature sufficiently great to avoid any likelihood of it being pierced by any of the components that interconnect the solar cells.

  3. Improved monolithic tandem solar cell

    SciTech Connect

    Wanlass, M.W.

    1991-04-23

    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 surf ace of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched.

  4. Silicon solar cells improved by lithium doping

    NASA Technical Reports Server (NTRS)

    Berman, P. A.

    1970-01-01

    Results of conference on characteristics of lithium-doped silicon solar cells and techniques required for fabrication indicate that output of cells has been improved to point where cells exhibit radiation resistance superior to those currently in use, and greater control and reproducibility of cell processing have been achieved.

  5. Improvements in InP solar cells

    NASA Technical Reports Server (NTRS)

    Keavney, Christopher; Vernon, Stanley M.; Haven, Victor E.

    1988-01-01

    Indium phosphide solar cells with very thin n-type emitters have been made by both ion implantation and metal-organic chemical vapor deposition. Air mass zero efficiencies as high as 18.8 percent (NASA measurement) have been achieved. The best cells, which were those made by ion implantation, show an open-circuit voltage of 873 mV, short-circuit current of 35.7 mA/sq cm, and fill factor of 0.829. Improvements are anticipated in all three of these parameters. Internal quantum efficiency peaks at over 90 percent in the red end of the spectrum, but drops to 54 percent in the blue end. Other cells have achieved 74 percent in the blue end. A preliminary investigation of InP solar cells on foreign substrates has been carried out. Although problems have been encountered with doping of the InP by the substrate, cells of 7.1 percent efficiency on silicon and cells of 9.4 percent, efficiency on GaAs have been made.

  6. Improved Solar-Cell Tunnel Junction

    NASA Technical Reports Server (NTRS)

    Daud, T.; Kachare, A.

    1986-01-01

    Efficiency of multiple-junction silicon solar cells increased by inclusion of p+/n+ tunnel junctions of highly doped GaP between component cells. Relatively low recombination velocity at GaP junction principal reason for recommending this material. Relatively wide band gap also helps increase efficiency by reducing optical losses.

  7. Solar cell having improved back surface reflector

    NASA Astrophysics Data System (ADS)

    Chai, A. T.

    1982-10-01

    The operating temperature is reduced and the output of a solar cell is increased by using a solar cell which carries electrodes in a grid finger pattern on its back surface. These electrodes are sintered at the proper temperature to provide good ohmic contact. After sintering, a reflective material is deposited on the back surface by vacuum evaporation. Thus, the application of the back surface reflector is separate from the back contact formation. Back surface reflectors formed in conjunction with separate grid finger configuration back contacts are more effective than those formed by full back metallization of the reflector material.

  8. Phthalocyanine Blends Improve Bulk Heterojunction Solar Cells

    PubMed Central

    Varotto, Alessandro; Nam, Chang-Yong; Radivojevic, Ivana; Tomé, Joao; Cavaleiro, José A.S.; Black, Charles T.; Drain, Charles Michael

    2010-01-01

    A core phthalocyanine platform allows engineering the solubility properties the band gap; shifting the maximum absorption toward the red. A simple method to increase the efficiency of heterojunction solar cells uses a self-organized blend of the phthalocyanine chromophores fabricated by solution processing. PMID:20136126

  9. Aluminum doping improves silicon solar cells

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Aluminum doped silicon solar cells with resistivities in the 10- to 20-ohm centimeter range have broad spectral response, high efficiency and long lifetimes in nuclear radiation environments. Production advantages include low material rejection and increased production yields, and close tolerance control.

  10. Improving the dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Willig, Frank

    2007-09-01

    Two dye sensitized solar cells (DSC) can be joined to form a tandem cell with two separate absorption ranges for the two different absorber materials. This can enhance the solar conversion efficiency and in particular the photovoltage of the DSC. Water splitting appears as a realistic long term target. The DSC tandem can be realized as n-n junction employing known dye molecules with optimal absorption spectra. Dye molecules with elongated shapes can be realized by covalently attaching a conducting bridge group terminated by an anchor group to a desired chromophore. Due to the long conducting bridge group separating the hole state of the dye from the surface of the semiconductor recombination is slowed down. The ordered molecular structure can be self-assembled on the recently introduced rod or cylinder shaped oxide electrodes but will not slow down recombination in the nm-cavities of the conventional TiO II Graetzel electrode.

  11. Silicon solar cell efficiency improvement: Status and outlook

    NASA Technical Reports Server (NTRS)

    Wolf, M.

    1985-01-01

    Efficiency and operating life is an economic attribute in silicon solar cells application. The efficiency improvements made during the 30 year existence of the silicon solar cells, from about 6% efficiency at the beginning to 19% in the most recent experimental cells is illustrated. In the more stationary periods, the effort was oriented towards improving radiation resistance and yields on the production lines, while, in other periods, the emphasis was on reaching new levels of efficiency through better cell design and improved material processing. First results were forthcoming from the recent efforts. Considerably more efficiency advancement in silicon solar cells is expected, and the anticipated attainment of efficiencies significantly above 20% is discussed. Major advances in material processing and in the resulting material perfection are required.

  12. Solar cell having improved front surface metallization

    SciTech Connect

    Lillington, D.R.; Mardesich, N.; Dill, H.G.; Garlick, G.F.J.

    1987-09-15

    This patent describes a solar cell comprising: a first layer of gallium arsenide semiconductor material of an N+ conductivity; a second layer of gallium arsenide semiconductor material of an N conductivity overlying the first layer; a third layer of gallium arsenide semiconductor material of a P conductivity overlying the N conductivity layer and forming a P-N junction therebetween. A layer of aluminium gallium arsenide semiconductor material of a p conductivity overlying the front major surface of the P conductivity third layer and having an exposed surface essentially parallel to the front major surface and at least one edge; a plurality of metallic contact lines made of a first metal alloy composition and being spaced apart by a first predetermined distance traversing the exposed surface and extending through the aluminium gallium arsenide layer to the front major surface and making electrical contact to the third layer; a plurality of longitudinally disposed metallic grid lines made of a second metal alloy composition and being spaced apart by a second predetermined distance located on the exposed surface of the aluminium gallium arsenide layer and which cross the metallic contact lines and make electrical contact to the metallic lines; a flat metallic strip disposed on the aluminium gallium arsenide layer exposed surface near the edge, the strip electrically coupling the metallic grid lines to one another; and a back contact located on the back major surface.

  13. Solar cell with improved electrical contacts

    SciTech Connect

    Cavicchi, B.T.; Dill, H.G.; Zemmrich, D.K.

    1987-10-06

    A solar cell is described comprising: a first layer of semiconductor material of a first conductivity type; a second layer of semiconductor material of a second opposite conductivity type disposed on the first layer forming a semiconductor junction therebetween. The first and second layers having first and second major essentially parallel surfaces, respectively, essentially parallel to the semiconductor junction; a layer of aluminum gallium arsenide semiconductor material of the second conductivity type disposed on the second major surface and having an exposed front major surface essentially parallel to the second major surface and further having grooves extending vertically to the second layer; electrically conductive material filling the grooves and electrically contacting the second layer to form metallic contact lines; a flat conductive bar transversely disposed on the exposed front major surface across the grooves and making electrical contact ot the electrically conductive material in the grooves; an electrically conductive flat strip disposed on the exposed major surface and spaced apart from the conductive bar; and at least one electrically conductive bridge electrically coupling the conductive bar to the contact strip.

  14. Method and apparatus for fabricating improved solar cell modules

    NASA Technical Reports Server (NTRS)

    Bloch, J. T.; Hanger, R. T.; Nichols, F. W. (Inventor)

    1980-01-01

    A method and apparatus for fabricating an improved solar cell module is described. The apparatus includes a supply drum for feeding a flexible strip having etched electrical circuitry deposited on it a supply drum for feeding into overlying engagement with the flexible strip a flexible tape having a pair of exposed tacky surfaces, and a plurality of rams for receiving and depositing a plurality of solar cells in side-by-side relation on an exposed tacky surface of the tape in electrical contacting engagement with the etched circuitry.

  15. Improvement of polysilicon solar cells by aluminum diffusion

    SciTech Connect

    Sundaresan, R.; Burk, D.E.; Fossum, J.G.

    1982-09-01

    Experimental results are presented that imply potential improvements afforded by aluminum diffusion in both bulk and thin-film polysilicon solar cells. With regard to bulk cells, gettering of intragrain defects by high-temperature aluminum diffusion, i.e., Al-Si alloying, is suggested. With regard to thin-film cells, substantial grain-boundary passivation by low-temperature aluminum diffusion (from the front surface) is indicated, and evaluated using EBIC measurements interpreted via numerical analysis of the underlying carrier transport problem. The actual benefit of the grain-boundary passivation to the open-circuit voltage of a thin-film cell is discussed.

  16. Berkeley Lab Sheds Light on Improving Solar Cell Efficiency

    SciTech Connect

    Lawrence Berkeley National Laboratory

    2007-07-20

    Typical manufacturing methods produce solar cells with an efficiency of 12-15%; and 14% efficiency is the bare minimum for achieving a profit. In work performed at the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley, CA, 5 10-486-577 1)--a US Department of Energy national laboratory that conducts unclassified scientific research and is managed by the University of California--scientist Scott McHugo has obtained keen insights into the impaired performance of solar cells manufactured from polycrystalline silicon. The solar cell market is potentially vast, according to Berkeley Lab. Lightweight solar panels are highly beneficial for providing electrical power to remote locations in developing nations, since there is no need to build transmission lines or truck-in generator fuel. Moreover, industrial nations confronted with diminishing resources have active programs aimed at producing improved, less expensive solar cells. 'In a solar cell, there is a junction between p-type silicon and an n-type layer, such as diffused-in phosphorous', explained McHugo, who is now with Berkeley Lab's Accelerator and Fusion Research Division. 'When sunlight is absorbed, it frees electrons, which start migrating in a random-walk fashion toward that junction. If the electrons make it to the junction; they contribute to the cell's output of electric current. Often, however, before they reach the junction, they recombine at specific sites in the crystal' (and, therefore, cannot contribute to current output). McHugo scrutinized a map of a silicon wafer in which sites of high recombination appeared as dark regions. Previously, researchers had shown that such phenomena occurred not primarily at grain boundaries in the polycrystalline material, as might be expected, but more often at dislocations in the crystal. However, the dislocations themselves were not the problem. Using a unique heat treatment technique, McHugo performed electrical measurements to investigate the material

  17. Improved Electrodes and Electrolytes for Dye-Based Solar Cells

    SciTech Connect

    Harry R. Allcock; Thomas E. Mallouk; Mark W. Horn

    2011-10-26

    The most important factor in limiting the stability of dye-sensitized solar cells is the use of volatile liquid solvents in the electrolytes, which causes leakage during extended operation especially at elevated temperatures. This, together with the necessary complex sealing of the cells, seriously hampers the industrial-scale manufacturing and commercialization feasibilities of DSSCs. The objective of this program was to bring about a significant improvement in the performance and longevity of dye-based solar cells leading to commercialization. This had been studied in two ways first through development of low volatility solid, gel or liquid electrolytes, second through design and fabrication of TiO2 sculptured thin film electrodes.

  18. Improved performance design of gallium arsenide solar cells for space

    NASA Technical Reports Server (NTRS)

    Parekh, R. H.; Barnett, A. M.

    1984-01-01

    An improved design, shallow junction heteroface, n-p, gallium arsenide solar cell for space applications is reported, with a predicted AM0 efficiency in the 21.9 to 23.0 percent range. The optimized n-p structure, while slightly more efficient, has the added advantage of being less susceptible to radiation-induced degradation by virtue of this thin top junction layer. Detailed spectral response curves and an analysis of the loss mechanisms are reported. The details of the design are readily measurable. The optimized designs were reached by quantifying the dominant loss mechanisms and then minimizing them by using computer simulations.

  19. 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.

  20. Compact Flyeye concentrator with improved irradiance uniformity on solar cell

    NASA Astrophysics Data System (ADS)

    Zhuang, Zhenfeng; Yu, Feihong

    2013-08-01

    A Flyeye concentrator with improved irradiance distribution on the solar cell in a concentrator photovoltaic system is proposed. This Flyeye concentrator is composed of four surfaces: a refractive surface, mirror surface, freeform surface, and transmissive surface. Based on the principles of geometrical optics, the contours of the proposed Flyeye concentrator are calculated according to Fermat's principle, the edge-ray principle, and the ray reversibility principle without solving partial differential equations or using an optimization algorithm, therefore a slope angle control method is used to construct the freeform surface. The solid model is established by applying a symmetry of revolution around the optical axis. Additionally, the optical performance for the Flyeye concentrator is simulated and analyzed by Monte-Carlo method. Results show that the Flyeye concentrator optical efficiency of >96.2% is achievable with 1333× concentration ratio and ±1.3 deg acceptance angle, and 1.3 low aspect ratio (average thickness to entry aperture diameter ratio). Moreover, comparing the Flyeye concentrator specification to that of the Köhler concentrator and the traditional Fresnel-type concentrator, results indicate that this concentrator has the advantages of improved uniformity, reduced thickness, and increased tolerance to the incident sunlight.

  1. Improved hybrid solar cells via in situ UV-polymerization.

    SciTech Connect

    Tepavcevic, S.; Darling, S. B.; Dimitrijevic, N. M.; Rajh, T.; Sibener, S. J.; Univ. of Chicago

    2009-08-03

    One approach for making inexpensive inorganic-organic hybrid photovoltaic (PV) cells is to fill highly ordered TiO{sub 2} nanotube (NT) arrays with solid organic hole conductors such as conjugated polymers. Here, a new in situ UV polymerization method for growing polythiophene (UV-PT) inside TiO{sub 2} NTs is presented and compared to the conventional approach of infiltrating NTs with pre-synthesized polymer. A nanotubular TiO{sub 2} substrate is immersed in a 2,5-diiodothiophene (DIT) monomer precursor solution and then irradiated with UV light. The selective UV photodissociation of the C-I bond produces monomer radicals with intact {pi}-ring structure that further produce longer oligothiophene/PT molecules. Complete photoluminescence quenching upon UV irradiation suggests coupling between radicals created from DIT and at the TiO{sub 2} surface via a charge transfer complex. Coupling with the TiO{sub 2} surface improves UV-PT crystallinity and {pi}-{pi} stacking; flat photocurrent values show that charge recombination during hole transport through the polymer is negligible. A non-ideal, backside-illuminated setup under illumination of 620-nm light yields a photocurrent density of {approx} 5 {micro}A cm{sup -2} - surprisingly much stronger than with comparable devices fabricated with polymer synthesized ex situ. Since in this backside architecture setup we illuminate the cell through the Ag top electrode, there is a possibility for Ag plasmon-enhanced solar energy conversion. By using this simple in situ UV polymerization method that couples the conjugated polymer to the TiO{sub 2} surface, the absorption of sunlight can be improved and the charge carrier mobility of the photoactive layer can be enhanced.

  2. Improved hybrid solar cells via in situ UV polymerization.

    PubMed

    Tepavcevic, Sanja; Darling, Seth B; Dimitrijevic, Nada M; Rajh, Tijana; Sibener, Steven J

    2009-08-01

    One approach for making inexpensive inorganic-organic hybrid photovoltaic (PV) cells is to fill highly ordered TiO(2) nanotube (NT) arrays with solid organic hole conductors such as conjugated polymers. Here, a new in situ UV polymerization method for growing polythiophene (UV-PT) inside TiO(2) NTs is presented and compared to the conventional approach of infiltrating NTs with pre-synthesized polymer. A nanotubular TiO(2) substrate is immersed in a 2,5-diiodothiophene (DIT) monomer precursor solution and then irradiated with UV light. The selective UV photodissociation of the C--I bond produces monomer radicals with intact pi-ring structure that further produce longer oligothiophene/PT molecules. Complete photoluminescence quenching upon UV irradiation suggests coupling between radicals created from DIT and at the TiO(2) surface via a charge transfer complex. Coupling with the TiO(2) surface improves UV-PT crystallinity and pi-pi stacking; flat photocurrent values show that charge recombination during hole transport through the polymer is negligible. A non-ideal, backside-illuminated setup under illumination of 620-nm light yields a photocurrent density of approximately 5 microA cm(2)-surprisingly much stronger than with comparable devices fabricated with polymer synthesized ex situ. Since in this backside architecture setup we illuminate the cell through the Ag top electrode, there is a possibility for Ag plasmon-enhanced solar energy conversion. By using this simple in situ UV polymerization method that couples the conjugated polymer to the TiO(2) surface, the absorption of sunlight can be improved and the charge carrier mobility of the photoactive layer can be enhanced. PMID:19367599

  3. Development of economical improved thick film solar cell contact

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1979-01-01

    Metal screened electrodes were investigated with base metal pastes and silver systems being focused upon. Contact resistance measurements were refined. A facility allowing fixing in hydrogen and other atmospheres was acquired. Several experiments were made applying screenable pastes to solar cells. Doping investigations emphasized eutectic alloys reduced to powders. Metal systems were reviewed and base metal experiments were done with nickel and copper using lead and tin as the frit metals. Severe adhesion problems were experienced with hydrogen atmospheres in all metal systems. A two step firing schedule was devised. Aluminum-silicon and aluminum-germanium eutectic doping additions to copper pastes were tried on 2 1/4 in diameter solar cell back contacts, both with good results.

  4. Methods for improving solar cell open circuit voltage

    DOEpatents

    Jordan, John F.; Singh, Vijay P.

    1979-01-01

    A method for producing a solar cell having an increased open circuit voltage. A layer of cadmium sulfide (CdS) produced by a chemical spray technique and having residual chlorides is exposed to a flow of hydrogen sulfide (H.sub.2 S) heated to a temperature of 400.degree.-600.degree. C. The residual chlorides are reduced and any remaining CdCl.sub.2 is converted to CdS. A heterojunction is formed over the CdS and electrodes are formed. Application of chromium as the positive electrode results in a further increase in the open circuit voltage available from the H.sub.2 S-treated solar cell.

  5. Methods For Improving Polymeric Materials For Use In Solar Cell Applications

    DOEpatents

    Hanoka, Jack I.

    2003-07-01

    A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

  6. Methods For Improving Polymeric Materials For Use In Solar Cell Applications

    DOEpatents

    Hanoka, Jack I.

    2001-11-20

    A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

  7. Manipulating Light to Understand and Improve Solar Cells (494th Brookhaven Lecture)

    SciTech Connect

    Eisaman, Matthew

    2014-04-16

    Energy consumption around the world is projected to approximately triple by the end of the century, according to the 2005 Report from the U.S. Department of Energy's Basic Energy Sciences Workshop on Solar Energy Utilization. Much will change in those next 86 years, but for all the power the world needs—for everything from manufacturing and transportation to air conditioning and charging cell phone batteries—improved solar cells will be crucial to meet this future energy demand with renewable energy sources. At Brookhaven Lab, scientists are probing solar cells and exploring variations within the cells—variations that are so small they are measured in billionths of a meter—in order to make increasingly efficient solar cells and ultimately help reduce the overall costs of deploying solar power plants. Dr. Eisaman will discuss DOE's Sunshot Initiative, which aims to reduce the cost of solar cell-generated electricity by 2020. He will also discuss how he and collaborators at Brookhaven Lab are probing different material compositions within solar cells, measuring how efficiently they collect electrical charge, helping to develop a new class of solar cells, and improving solar-cell manufacturing processes.

  8. Nanoetching process on silicon solar cell wafers during mass production for surface texture improvement.

    PubMed

    Ahn, Chisung; Kulkarni, Atul; Ha, Soohyun; Cho, Yujin; Kim, Jeongin; Park, Heejin; Kim, Taesung

    2014-12-01

    Major challenge in nanotechnology is to improve the solar cells efficiency. This can be achieved by controlling the silicon solar cell wafer surface structure. Herein, we report a KOH wet etching process along with an ultrasonic cleaning process to improve the surface texture of silicon solar cell wafers. We evaluated the KOH temperature, concentration, and ultra-sonication time. It was observed that the surface texture of the silicon solar wafer changed from a pyramid shape to a rectangular shape under edge cutting as the concentration of the KOH solution was increased. We controlled the etching time to avoid pattern damage and any further increase of the reflectance. The present study will be helpful for the mass processing of silicon solar cell wafers with improved reflectance. PMID:25971104

  9. 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.

  10. Photonic crystals for improving light absorption in organic solar cells

    SciTech Connect

    Duché, D. Le Rouzo, J.; Masclaux, C.; Gourgon, C.

    2015-02-07

    We theoretically and experimentally study the structuration of organic solar cells in the shape of photonic crystal slabs. By taking advantage of the optical properties of photonic crystals slabs, we show the possibility to couple Bloch modes with very low group velocities in the active layer of the cells. These Bloch modes, also called slow Bloch modes (SBMs), allow increasing the lifetime of photons within the active layer. Finally, we present experimental demonstration performed by using nanoimprint to directly pattern the standard poly-3-hexylthiophène:[6,6]-phenyl-C61-butiryc acid methyl ester organic semiconductor blend in thin film form in the shape of a photonic crystal able to couple SBMs. In agreement with the model, optical characterizations will demonstrate significant photonic absorption gains.

  11. Hydrophobic Organic Hole Transporters for Improved Moisture Resistance in Metal Halide Perovskite Solar Cells.

    PubMed

    Leijtens, Tomas; Giovenzana, Tommaso; Habisreutinger, Severin N; Tinkham, Jonathan S; Noel, Nakita K; Kamino, Brett A; Sadoughi, Golnaz; Sellinger, Alan; Snaith, Henry J

    2016-03-01

    Solar cells based on organic-inorganic perovskite semiconductor materials have recently made rapid improvements in performance, with the best cells performing at over 20% efficiency. With such rapid progress, questions such as cost and solar cell stability are becoming increasingly important to address if this new technology is to reach commercial deployment. The moisture sensitivity of commonly used organic-inorganic metal halide perovskites has especially raised concerns. Here, we demonstrate that the hygroscopic lithium salt commonly used as a dopant for the hole transport material in perovskite solar cells makes the top layer of the devices hydrophilic and causes the solar cells to rapidly degrade in the presence of moisture. By using novel, low cost, and hydrophobic hole transporters in conjunction with a doping method incorporating a preoxidized salt of the respective hole transporters, we are able to prepare efficient perovskite solar cells with greatly enhanced water resistance. PMID:26859777

  12. Recent improvements in materials for thin GaAs and multibandgap solar cells

    SciTech Connect

    Benner, J P

    1985-05-01

    The High Efficiency Concepts Program at SERI supports research on III-V compound semiconductors with the objective of achieving the maximum attainable photovoltaic conversion efficiencies for terrestrial solar electric power. The outcome of this research may also affect the future of space photovoltaic cells. While the interest in thin-film, high-efficiency solar cells for terrestrial applications is driven principally by consideration of system costs, such cells would also improve the power density of space power arrays.

  13. Improved Single-Source Precursors for Solar-Cell Absorbers

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Harris, Jerry; Hepp, Aloysius

    2007-01-01

    Improved single-source precursor compounds have been invented for use in spray chemical vapor deposition (spray CVD) of chalcopyrite semiconductor absorber layers of thin-film cells. A "single-source precursor compound" is a single molecular compound that contains all the required elements, which when used under the spray CVD conditions, thermally decomposes to form CuIn(x)Ga(1-x)S(y)Se(2-y).

  14. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

    NASA Astrophysics Data System (ADS)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  15. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

    PubMed

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-01-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes. PMID:25692264

  16. Improved performance in GaInNAs solar cells by hydrogen passivation

    SciTech Connect

    Fukuda, M.; Whiteside, V. R.; Keay, J. C.; Meleco, A.; Sellers, I. R.; Hossain, K.; Golding, T. D.; Leroux, M.; Al Khalfioui, M.

    2015-04-06

    The effect of UV-activated hydrogenation on the performance of GaInNAs solar cells is presented. A proof-of-principle investigation was performed on non-optimum GaInNAs cells, which allowed a clearer investigation of the role of passivation on the intrinsic nitrogen-related defects in these materials. Upon optimized hydrogenation of GaInNAs, a significant reduction in the presence of defect and impurity based luminescence is observed as compared to that of unpassivated reference material. This improvement in the optical properties is directly transferred to an improved performance in solar cell operation, with a more than two-fold improvement in the external quantum efficiency and short circuit current density upon hydrogenation. Temperature dependent photovoltaic measurements indicate a strong contribution of carrier localization and detrapping processes, with non-radiative processes dominating in the reference materials, and evidence for additional strong radiative losses in the hydrogenated solar cells.

  17. A synergetic application of surface plasmon and field effect to improve Si solar cell performance.

    PubMed

    Zhou, Zhi-Quan; Wang, Liang-Xing; Shi, Wei; Sun, Shu-Lin; Lu, Ming

    2016-04-01

    We report a synergetic application of surface plasmon (SP) and field effect (FE) to improve crystalline Si solar cell performance. The SPs are supported by small-sized Ag nanoparticles with an average diameter of 36.7 nm. The localized SP electromagnetic field from Ag nanoparticles excites extra electron-hole pairs at the surface region of the Si solar cell emitter, and meanwhile, the electron-hole pairs are detached by the electrostatic field that crosses the emitter surface. This synergism of SP and FE produces extra charges and enhances the Si solar cell efficiency. As compared to a Si solar cell applying SP and FE independently, a more than 10% efficiency enhancement is achieved by using them synergistically. PMID:26902838

  18. A synergetic application of surface plasmon and field effect to improve Si solar cell performance

    NASA Astrophysics Data System (ADS)

    Zhou, Zhi-Quan; Wang, Liang-Xing; Shi, Wei; Sun, Shu-Lin; Lu, Ming

    2016-04-01

    We report a synergetic application of surface plasmon (SP) and field effect (FE) to improve crystalline Si solar cell performance. The SPs are supported by small-sized Ag nanoparticles with an average diameter of 36.7 nm. The localized SP electromagnetic field from Ag nanoparticles excites extra electron-hole pairs at the surface region of the Si solar cell emitter, and meanwhile, the electron-hole pairs are detached by the electrostatic field that crosses the emitter surface. This synergism of SP and FE produces extra charges and enhances the Si solar cell efficiency. As compared to a Si solar cell applying SP and FE independently, a more than 10% efficiency enhancement is achieved by using them synergistically.

  19. Improved solar efficiency by introducing graphene oxide in purple cabbage dye sensitized TiO2 based solar cell

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, Ahmed A.; Gupta, R. K.; Kahol, P. K.; Wageh, S.; Al-Turki, Y. A.; El Shirbeeny, W.; Yakuphanoglu, F.

    2014-04-01

    Natural dye extracted from purple cabbage was used for fabrication of TiO2 dye-sensitized solar cells (DSSCs). The effect of light intensity on the solar efficiency of the device was investigated. It was observed that the efficiency of the DSSC increases with increasing the light intensity e.g. the efficiency of the solar cell increases from 0.013±0.002% to 0.150±0.020% by increase in light intensity from 30 to 100 mW/cm2, respectively. The solar efficiency of the natural dye used in this research was compared with commercial dye (N 719) under similar experimental conditions and observed that the natural (purple cabbage) dye has higher efficiency (0.150±0.020%) than N 719 (0.078±0.002%). It was further evaluated that the efficiency of the fabricated solar cell could improve by incorporating graphene oxide. The efficiency of the TiO2 dye-sensitized solar cell was found to increase from 0.150±0.020% to 0.361±0.009% by incorporating graphene oxide into purple cabbage dye.

  20. Improved photovoltaic performance of silicon nanowire/organic hybrid solar cells by incorporating silver nanoparticles

    PubMed Central

    2013-01-01

    Silicon nanowire (SiNW) arrays show an excellent light-trapping characteristic and high mobility for carriers. Surface plasmon resonance of silver nanoparticles (AgNPs) can be used to increase light scattering and absorption in solar cells. We fabricated a new kind of SiNW/organic hybrid solar cell by introducing AgNPs. Reflection spectra confirm the improved light scattering of AgNP-decorated SiNW arrays. A double-junction tandem structure was designed to manufacture our hybrid cells. Both short-circuit current and external quantum efficiency measurements show an enhancement in optical absorption of organic layer, especially at lower wavelengths. PMID:23418988

  1. Improvement of a Si solar cell efficiency using pure and Fe3+ doped PVA films

    NASA Astrophysics Data System (ADS)

    Khalifa, N.; Kaouach, H.; Chtourou, R.

    2015-07-01

    One of the most important key driving the economic viability of solar cells is the high efficiency. This research focuses on the enhancement of commercial Si solar cell performance by deposing a pure and Fe3+ doped polyvinyl alcohol (PVA) layer on the top of the Si wafer of the considered cells. The use of such polymer to improve solar cells efficiency is actually a first. The authors will rely on the optical characteristics of the pure and doped PVA films including absorption and emission properties to justify the effect on Si cells. Commercial monocrystalline silicon solar cells of 15 cm2 (0.49 V/460 mA) are used in this work. Films of almost 80 μm of the ferric polymer are deposed on the cells. Films with the same thickness are characterized by UV-Vis spectroscopy and photoluminescent emission of the films is then investigated. The electrical properties of the cells with and without the organometallic layer are evaluated. It will be deduced an important improvement of all electrical parameters, including short-circuit current, open-circuit voltage, fill factor and spatially the conversion efficiency by almost 3%.

  2. Interlaced semi-ellipsoid nanostructures for improving light trapping of ultrathin crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Ge; Li, Juntao; Wang, Xuehua

    2015-10-01

    Ultrathin crystalline silicon (c-Si) solar cells, which are of several micrometers thick, have attracted much attention in recent years, since it can greatly save raw materials than the traditional ones. To enhance the absorption, as well as to improve the cell efficiency, of the ultrathin c-Si, light trapping nanostructures are used to increase the effective absorption length to close to the 4n2 of the materials thickness, which is determined by the Lambertian limit. Here, we propose a novel interlaced semi-ellipsoid nanostructures (ISENs) to improve the performance of ultrathin c-Si solar cells. In this structure, the large and small periods in x and y direction can improve the light trapping capability at long and short wavelengths respectively. Meanwhile, the graded refractive index of the surface can act as the antireflection coating. By optimizing the ISENs, the short circuit current density of 30.15mA/cm2 was achieved by simulations for a 2 μm thick c-Si solar cell with rx = 500 nm, ry = 200 nm, rz= 550 nm and without antireflection coating and metal back reflector. The absorption is close to 87% of the Lambertian limit with equivalent thickness. We expect this structure can be fabricated by low cost nanosphere lithography technology and used to improve the efficiency of the ultrathin c-Si solar cells.

  3. Development of an improved high efficiency thin silicon solar cell

    NASA Technical Reports Server (NTRS)

    Wrigley, C.; Storti, G.

    1978-01-01

    Efforts were directed towards investigating means of producing more effective high-low junctions at the back of the cell. Cells with output power up to 77 mW (AM0 efficiency of 14.2 percent) were fabricated. Some reflectivity studies were also made. Deliveries of 2 cm x 2 cm experimental cells included a number having AM0 outputs greater than 70 mW.

  4. Improving the performance of P3HT/PCBM solar cells with squaraine dye

    NASA Astrophysics Data System (ADS)

    Huang, Jing-Shun; Goh, Tenghooi; Li, Xiaokai; Sfeir, Matthew Y.; Bielinski, Elizabeth A.; Tomasulo, Stephanie; Lee, Minjoo L.; Hazari, Nilay; Taylor, André D.

    2013-10-01

    Expanding the spectral absorption breadth and efficiently harvesting excitons are crucial towards creating highly efficient polymer solar cells. Here we describe a strategy to realize broad-band light harvesting in poly(3-hexylthiophene) (P3HT)-based solar cells. We introduce the use of squaraine dye molecules that play a dual role towards improving P3HT-based solar cells. The first benefit is an increase in the spectral absorption in the near infrared region. The second advantage is the collection of excitons close to the interfacial heterojunctions via Förster resonance energy transfer (FRET). Unlike traditional multi-blend systems, where each donor works independently in separate spectral responses, FRET-based systems enable the effective use of multiple donors with significant improvements in light absorption and conversion. Ultrafast transient absorption experiments show that the excitation energy from P3HT can be transferred rapidly (within a few picoseconds) and efficiently (up to 96%) to the squaraine via FRET. As a result, the overall power conversion efficiency is improved. This architecture opens up a new paradigm towards transformative improvements of polymer solar cells.

  5. Development of an Improved High Efficiency Thin Silicon Solar Cell

    NASA Technical Reports Server (NTRS)

    Storti, G.; Wrigley, C.

    1979-01-01

    Breakage and front contact failure in high efficiency, textured ultrathin cells was reduced as a consequence of the introduction of process modifications. In a small production run, over one hundred ultrathin cells, having an average AMO efficiency of 13%, were fabricated from 10-25 ohm cm silicon. An in-house aluminum paste for back surface field formation was developed that resulted in cell efficiencies equivalent to those from commercial pastes. The quality of the back surface field was found to be dependent on the orientation of the silicon slice during alloying.

  6. Improved Transparent Conducting Oxides Boost Performance of Thin-Film Solar Cells (Fact Sheet)

    SciTech Connect

    Not Available

    2011-02-01

    Today?s thin-film solar cells could not function without transparent conducting oxides (TCOs). TCOs act as a window, both protecting the cell and allowing light to pass through to the cell?s active layers. Until recently, TCOs were seen as a necessary, but static, layer of a thin-film photovoltaic (PV) cell. But a group of researchers at the National Renewable Energy Laboratory (NREL) has identified a pathway to producing improved TCO films that demonstrate higher infrared transparency. To do so, they have modified the TCOs in ways that did not seem possible a few years ago.

  7. Improving solar cell efficiencies by down-conversion of high-energy photons

    NASA Astrophysics Data System (ADS)

    Trupke, T.; Green, M. A.; Wurfel, P.

    2002-08-01

    One of the major loss mechanisms leading to low energy conversion efficiencies of solar cells is the thermalization of charge carriers generated by the absorption of high-energy photons. These losses can largely be reduced in a solar cell if more than one electron-hole pair can be generated per incident photon. A method to realize multiple electron-hole pair generation per incident photon is proposed in this article. Incident photons with energies larger than twice the band gap of the solar cell are absorbed by a luminescence converter, which transforms them into two or more lower energy photons. The theoretical efficiency limit of this system for nonconcentrated sunlight is determined as a function of the solar cell's band gap using detailed balance calculations. It is shown that a maximum conversion efficiency of 39.63% can be achieved for a 6000 K blackbody spectrum and for a luminescence converter with one intermediate level. This is a substantial improvement over the limiting efficiency of 30.9%, which a solar cell exposed directly to nonconcentrated radiation may have under the same assumption of radiative recombination only.

  8. Small-molecule organic solar cells with improved stability

    NASA Astrophysics Data System (ADS)

    Song, Q. L.; Li, F. Y.; Yang, H.; Wu, H. R.; Wang, X. Z.; Zhou, W.; Zhao, J. M.; Ding, X. M.; Huang, C. H.; Hou, X. Y.

    2005-11-01

    A stable small-molecule organic photovoltaic device with structure of ITO⧹donor⧹acceptor⧹buffer⧹cathode is presented. A thin layer (˜60 Å) of tris-8-hydroxy-quinolinato aluminum (Alq 3) instead of bathocuproine (BCP) is adopted as the buffer of the device, resulting in 150 times longer lifetime. The power conversion efficiency of the device is 2.11% under 75 mW/cm 2 AM1.5G simulated illumination, and no perceptible efficiency degradation is observed for long-term storage of the device in vacuum or nitrogen-filled glove box. More effective blocking of Alq 3 than BCP against diffusion of cathode atoms and permeation of oxygen and/or water molecules is considered as the main reason for the improved performance of the new device.

  9. Solar cells

    NASA Astrophysics Data System (ADS)

    Cuquel, A.; Roussel, M.

    The physical and electronic characteristics of solar cells are discussed in terms of space applications. The principles underlying the photovoltaic effect are reviewed, including an analytic model for predicting the performance of individual cells and arrays of cells. Attention is given to the effects of electromagnetic and ionizing radiation, micrometeors, thermal and mechanical stresses, pollution and degassing encountered in space. The responses of different types of solar cells to the various performance-degrading agents are examined, with emphasis on techniques for quality assurance in the manufacture and mounting of Si cells.

  10. Improvement of Electrical Properties of Silicon Quantum Dot Superlattice Solar Cells with Diffusion Barrier Layers

    NASA Astrophysics Data System (ADS)

    Yamada, Shigeru; Kurokawa, Yasuyoshi; Miyajima, Shinsuke; Konagai, Makoto

    2013-04-01

    We investigate the effects of a niobium-doped titanium dioxide (TiO2:Nb) diffusion barrier layer on the performance of silicon quantum dot superlattice (Si-QDSL) solar cells. The insertion of a 2-nm-thick TiO2:Nb layer significantly reduces phosphorus diffusion from a highly doped n-type layer into a Si-QDSL layer during thermal annealing at 900 °C. The phosphorous concentration in the Si-QDSL layer of the solar cell with the TiO2:Nb diffusion barrier layer was found to be less than 1018 cm-3, which is approximately two orders of magnitude lower than that of the solar cell without the diffusion barrier layer. The reduction in phosphorous concentration leads to the improvement of photo-generated carrier collection in the Si-QDSL layer. The short circuit current density of the solar cell with the diffusion barrier layer was dramatically improved to 1.6 mA/cm2 without the degradation of open circuit voltage and fill factor.

  11. Polymer TiO2 solar cells: TiO2 interconnected network for improved cell performance

    NASA Astrophysics Data System (ADS)

    Oey, C. C.; Djurisic, A. B.; Wang, H.; Man, K. K. Y.; Chan, W. K.; Xie, M. H.; Leung, Y. H.; Pandey, A.; Nunzi, J.-M.; Chui, P. C.

    2006-02-01

    A titanium dioxide porous network structure was synthesized using a poly(styrene-block-polyethylene oxide) diblock copolymer template. The influence of the titanium precursor concentration and annealing temperature on the obtained morphology was studied. Heterojunction solar cells consisting of TiO2 porous network structure and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) were fabricated. The influence of the MEH-PPV layer thickness and device architecture on the solar cell performance was investigated. For an optimized device structure, a short-circuit current as high as 3.3 mA cm-2 is obtained under simulated solar illumination with an air mass AM 1.5 filter. The improved higher short-circuit current compared to other reports on MEH-PPV /TiO2 heterojunction cells can be attributed to improved morphology of the TiO2 layer.

  12. Improving efficiency of silicon heterojunction solar cells by surface texturing of silicon wafers using tetramethylammonium hydroxide

    NASA Astrophysics Data System (ADS)

    Wang, Liguo; Wang, Fengyou; Zhang, Xiaodan; Wang, Ning; Jiang, Yuanjian; Hao, Qiuyan; Zhao, Ying

    2014-12-01

    Texturing of silicon surfaces is an effective method for improving the efficiency of silicon solar cells. Etching by using tetramethylammonium hydroxide (TMAH) is more attractive than other texturing processes because TMAH is non-toxic, and high-quality anisotropic features can be realized without any metal ion contaminants. In this study, TMAH texturing conditions are varied to optimize the surface morphology of silicon wafers. Excellent optical properties are obtained. This is because of the formation of pyramidal structures with different random sizes but uniform shapes; in fact, when the optimal etching conditions (2% TMAH, 10% isopropyl alcohol (IPA) at 80 °C) are used, the reflectance is only 10.7%. In comparison with NaOH texturing, the TMAH process described here yields smaller pyramids with smoother (111) facets, leading to improved performance in silicon heterojunction solar cells, with a conversion efficiency of 17.8%.

  13. Tailoring the Interface to Improve Voc in Dye-Sensitized Solar Cells

    SciTech Connect

    Neale, N. R.; Kopidakis, N.; van de Lagemaat, J.; Frank, A. J.

    2005-01-01

    Adding certain adsorbents in conjunction with the sensitizing dye employed in high-efficiency TiO2 nanoparticle solar cells has been shown to increase the photovoltage. It is has been speculated that the increased photovoltage is due to these hydrophobic adsorbents passivating surface states that mitigate the recombination of photoinjected electrons with redox species in the electrolyte. In collaboration with the DOE Office of Science Program, we are conducting transient-photovoltage measurements to determine the mechanism for the improved photovoltage.

  14. Improved performance of polymer solar cells by using inorganic, organic, and doped cathode buffer layers

    NASA Astrophysics Data System (ADS)

    Taohong, Wang; Changbo, Chen; Kunping, Guo; Guo, Chen; Tao, Xu; Bin, Wei

    2016-03-01

    The interface between the active layer and the electrode is one of the most critical factors that could affect the device performance of polymer solar cells. In this work, based on the typical poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) polymer solar cell, we studied the effect of the cathode buffer layer (CBL) between the top metal electrode and the active layer on the device performance. Several inorganic and organic materials commonly used as the electron injection layer in an organic light-emitting diode (OLED) were employed as the CBL in the P3HT:PCBM polymer solar cells. Our results demonstrate that the inorganic and organic materials like Cs2CO3, bathophenanthroline (Bphen), and 8-hydroxyquinolatolithium (Liq) can be used as CBL to efficiently improve the device performance of the P3HT:PCBM polymer solar cells. The P3HT:PCBM devices employed various CBLs possess power conversion efficiencies (PCEs) of 3.0%-3.3%, which are ca. 50% improved compared to that of the device without CBL. Furthermore, by using the doped organic materials Bphen:Cs2CO3 and Bphen:Liq as the CBL, the PCE of the P3HT:PCBM device will be further improved to 3.5%, which is ca. 70% higher than that of the device without a CBL and ca. 10% increased compared with that of the devices with a neat inorganic or organic CBL. Project supported by the National Natural Science Foundation of China (Grant No. 61204014), the “Chenguang” Project (13CG42) supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation, China, and the Shanghai University Young Teacher Training Program of Shanghai Municipality, China.

  15. Realization of improved efficiency on nanostructured multicrystalline silicon solar cells for mass production.

    PubMed

    Lin, X X; Zeng, Y; Zhong, S H; Huang, Z G; Qian, H Q; Ling, J; Zhu, J B; Shen, W Z

    2015-03-27

    We report the realization of both excellent optical and electrical properties of nanostructured multicrystalline silicon solar cells by a simple and industrially compatible technique of surface morphology modification. The nanostructures are prepared by Ag-catalyzed chemical etching and subsequent NaOH treatment with controllable geometrical parameters and surface area enhancement ratio. We have examined in detail the influence of different surface area enhancement ratios on reflectance, carrier recombination characteristics and cell performance. By conducting a quantitative analysis of these factors, we have successfully demonstrated a higher-than-traditional output performance of nanostructured multicrystalline silicon solar cells with a low average reflectance of 4.93%, a low effective surface recombination velocity of 6.59 m s(-1), and a certified conversion efficiency of 17.75% on large size (156 × 156 mm(2)) silicon cells, which is ∼0.3% higher than the acid textured counterparts. The present work opens a potential prospect for the mass production of nanostructured solar cells with improved efficiencies. PMID:25736199

  16. Improving the efficiency of organic solar cells by varying the material concentration in the photoactive layer

    NASA Astrophysics Data System (ADS)

    Latimer, Kevin Anthony

    Polymer-fullerene bulk heterojunction solar cells have been a rapidly improving technology over the past decade. To further improve the relatively low energy conversion efficiencies of these solar cells, several modifications need to be made to the overall device structure. Emerging technologies include cells that are fabricated with interfacial layers to facilitate charge transport, and tandem structures are being introduced to harness the absorption spectrum of polymers with varying bandgap energies. When new structures are implemented, each layer of the cell must be optimized in order for the entire device to function efficiently. The most volatile layer of these devices is the photoactive layer solution of poly-3(hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC 61BM). Even slight variations in pre-application and post-treatment will lead to large variations in the electrical, physical, and optical properties of the solar cell module. To improve the effectiveness of the photoactive layer, the material concentration of P3HT and PC61BM in the liquid phase, prior to application, was altered. The weight ratio of P3HT to PC61BM was kept at a constant 1 to 0.8, while the amounts of each dissolved in 2 mL of chlorobenzene were varied. Solar cells were fabricated, and J-V characterizations were performed to determine the electrical traits of the devices. Atomic force microscopy (AFM) measurements were done on the photoactive layer films to determine the physical characteristics of the films such as overall surface topology and RMS roughness. Also, variable angle spectroscopic ellipsometry (VASE) was used to determine film thickness and extinction coefficient of the active layers. To further understand the optical properties of the polymer-fullerene blend, the absorption spectrum of the films were calculated through UV-VIS spectrophotometry. It was found that an increased concentration of the polymer-fullerene blend prior to application

  17. InP solar cell improvement by inverse delta-doping

    SciTech Connect

    Piprek, J.; Boeer, K.W.

    1994-12-31

    Recombination loss mechanisms in InP homojunction solar cells are analyzed using numerical modeling. To reduce the junction leakage current, it is proposed to introduce a thin undoped layer with low recombination center density near the pn-junction. This inverse delta-doping is found to be most beneficial in low efficiency p{sup +}n-InP cells, improving the open circuit voltage by 50 mV, the fill factor by 0.09, and the efficiency by 2 percentage points.

  18. Improving charge transport property and energy transfer with carbon quantum dots in inverted polymer solar cells

    SciTech Connect

    Liu, Chunyu; Chang, Kaiwen; Guo, Wenbin E-mail: chenwy@jlu.edu.cn Li, Hao; Shen, Liang; Chen, Weiyou E-mail: chenwy@jlu.edu.cn; Yan, Dawei E-mail: chenwy@jlu.edu.cn

    2014-08-18

    Carbon quantum dots (Cdots) are synthesized by a simple method and introduced into active layer of polymer solar cells (PSCs). The performance of doped devices was apparently improved, and the highest power conversion efficiency of 7.05% was obtained, corresponding to a 28.2% enhancement compared with that of the contrast device. The charge transport properties, resistance, impedance, and transient absorption spectrum are systematically investigated to explore how the Cdots affect on PSCs performance. This study reveals the importance of Cdots in enhancing the efficiency of PSCs and gives insight into the mechanism of charge transport improvement.

  19. Improving optical absorptivity of natural dyes for fabrication of efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hemmatzadeh, Reza; Mohammadi, Ahmad

    2013-11-01

    Efficient and cheap dye-sensitized solar cells (DSSCs) were fabricated using natural dyes from Pastinaca sativa and Beta vulgaris. Natural dyes are environmentally and economically superior to ruthenium-based dyes because they are nontoxic and cheap. However, the conversion efficiency of dye-sensitized solar cells based on natural dyes is low. One way to improve the DSSC performance is to enhance the absorptivity of extracted dyes. We investigated the influence of various factors in the extraction process, such as utilization of different extraction approaches, the acidity of extraction solvent, and different compounds of solvents on the optical absorption spectra. It was found that we could considerably enhance the optical absorptivity of dye and consequently the performance of DSSC by choosing a proper mixture of ethanol and water for extracting solvent and also the acidity of dye solution.

  20. Multi-scale surface texture to improve blue response of nanoporous black silicon solar cells

    NASA Astrophysics Data System (ADS)

    Toor, Fatima; Branz, Howard M.; Page, Matthew R.; Jones, Kim M.; Yuan, Hao-Chih

    2011-09-01

    We characterize the optical and carrier-collection physics of multi-scale textured p-type black Si solar cells with conversion efficiency of 17.1%. The multi-scale texture is achieved by combining density-graded nanoporous layer made by metal-assisted etching with micron-scale pyramid texture. We found that (1) reducing the thickness of nanostructured Si layer improves the short-wavelength spectral response and (2) multi-scale texture permits thinning of the nanostructured layer while maintaining low surface reflection. We have reduced the nanostructured layer thickness by 60% while retaining a solar-spectrum-averaged black Si reflectance of less than 2%. Spectral response at 450 nm has improved from 57% to 71%.

  1. All-silicon tandem solar cells: Practical limits for energy conversion and possible routes for improvement

    NASA Astrophysics Data System (ADS)

    Jia, Xuguang; Puthen-Veettil, Binesh; Xia, Hongze; Yang, Terry Chien-Jen; Lin, Ziyun; Zhang, Tian; Wu, Lingfeng; Nomoto, Keita; Conibeer, Gavin; Perez-Wurfl, Ivan

    2016-06-01

    Silicon nanocrystals (Si NCs) embedded in a dielectric matrix is regarded as one of the most promising materials for the third generation photovoltaics, owing to their tunable bandgap that allows fabrication of optimized tandem devices. Previous work has demonstrated fabrication of Si NCs based tandem solar cells by sputter-annealing of thin multi-layers of silicon rich oxide and SiO2. However, these device efficiencies were much lower than expected given that their theoretical values are much higher. Thus, it is necessary to understand the practical conversion efficiency limits for these devices. In this article, practical efficiency limits of Si NC based double junction tandem cells determined by fundamental material properties such as minority carrier, mobility, and lifetime are investigated. The practical conversion efficiency limits for these devices are significantly different from the reported efficiency limits which use Shockley-Queisser assumptions. Results show that the practical efficiency limit of a double junction cell (1.6 eV Si NC top cell and a 25% efficient c-Si PERL cell as the bottom cell) is 32%. Based on these results suggestions for improvement to the performance of Si nanocrystal based tandem solar cells in terms of the different parameters that were simulated are presented.

  2. Improving the performance of perovskite solar cells with glycerol-doped PEDOT:PSS buffer layer

    NASA Astrophysics Data System (ADS)

    Jian-Feng, Li; Chuang, Zhao; Heng, Zhang; Jun-Feng, Tong; Peng, Zhang; Chun-Yan, Yang; Yang-Jun, Xia; Duo-Wang, Fan

    2016-02-01

    In this paper, we investigate the effects of glycerol doping on transmittance, conductivity and surface morphology of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)) (PEDOT:PSS) and its influence on the performance of perovskite solar cells. . The conductivity of PEDOT:PSS is improved obviously by doping glycerol. The maximum of the conductivity is 0.89 S/cm when the doping concentration reaches 6 wt%, which increases about 127 times compared with undoped. The perovskite solar cells are fabricated with a configuration of indium tin oxide (ITO)/PEDOT:PSS/CH3NH3PbI3/PC61BM/Al, where PEDOT:PSS and PC61BM are used as hole and electron transport layers, respectively. The results show an improvement of hole charge transport as well as an increase of short-circuit current density and a reduction of series resistance, owing to the higher conductivity of the doped PEDOT:PSS. Consequently, it improves the whole performance of perovskite solar cell. The power conversion efficiency (PCE) of the device is improved from 8.57% to 11.03% under AM 1.5 G (100 mW/cm2 illumination) after the buffer layer has been modified. Project supported by the National Natural Science Foundation of China (Grant Nos. 61264002, 61166002, 91333206, and 51463011), the Natural Science Foundation of Gansu Province, China (Grant No. 1308RJZA159), the New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0840), the Research Project of Graduate Teacher of Gansu Province, China (Grant No. 2014A-0042), and the Postdoctoral Science Foundation from Lanzhou Jiaotong University, China.

  3. Solar cells

    NASA Astrophysics Data System (ADS)

    Treble, F. C.

    1980-11-01

    The history, state of the art, and future prospects of solar cells are reviewed. Solar cells are already competitive in a wide range of low-power applications, and during the 1980's they are expected to become cheaper to run than diesel or gasoline generators, the present mainstay of isolated communities. At this stage they will become attractive for water pumping, irrigation, and rural electrification, particularly in developing countries. With further cost reduction, they may be used to augment grid supplies in domestic, commercial, institutional, and industrial premises. Cost reduction to the stage where photovoltaics becomes economic for large-scale power generation in central stations depends on a technological breakthrough in the development of thin-film cells. DOE aims to reach this goal by 1990, so that by the end of the century about 20% of the estimated annual additions to their electrical generating capacity will be photovoltaic.

  4. Potential improvement of polysilicon solar cells by grain boundary and intragrain diffusion of aluminum

    SciTech Connect

    Sundaresan, R.; Burk, D.E.; Fossum, J.G.

    1984-02-15

    Experimental results are presented that imply potential improvements afforded by aluminum diffusion in both bulk and thin-film polysilicon solar cells. For bulk cells, a high-temperature aluminum diffusion (alloying) is shown to increase the minority-carrier diffusion length by gettering intragrain impurities. The role of the grain boundaries in this process and the influence of a light bias on the carrier lifetime are discussed. For thin-film cells, a low-temperature aluminum diffusion is shown to substantially passivate grain boundaries and hence decrease the recombination velocity. The decrease is evaluated using electron-beam-induced-current (EBIC) measurements interpreted via numerical analysis of the underlying carrier-transport problem. The actual benefit of the grain-boundary passivation to the open-circuit voltage of a thin-film cell is discussed.

  5. Micro-textures for efficient light trapping and improved electrical performance in thin-film nanocrystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Tan, Hairen; Psomadaki, Efthymia; Isabella, Olindo; Fischer, Marinus; Babal, Pavel; Vasudevan, Ravi; Zeman, Miro; Smets, Arno H. M.

    2013-10-01

    Micro-textures with large opening angles and smooth U-shape are applied to nanocrystalline silicon (nc-Si:H) solar cells. The micro-textured substrates result in higher open-circuit-voltage (Voc) and fill-factor (FF) than nano-textured substrates. For thick solar cells, high Voc and FF are maintained. Particularly, the Voc only drops from 564 to 541 mV as solar cell thickness increases from 1 to 5 μm. The improvement in electrical performance of solar cells is ascribed to the growth of dense nc-Si:H layers free from defective filaments on micro-textured substrates. Thereby, micromorph tandem solar cells with an initial efficiency of 13.3%, Voc = 1.464 V, and FF = 0.759 are obtained.

  6. Advanced nanostructured materials and their application for improvement of sun-light harvesting and efficiency of solar cells

    NASA Astrophysics Data System (ADS)

    Dimova-Malinovska, D.

    2016-02-01

    This review describes the application of different nanostructured materials in solar cells technology for improvement of sun-light harvesting and their efficiency. Several approaches have recently been proposed to increase the efficiency of solar cells above the theoretical limit which are based on a “photon management” concept that employs such phenomena as: (i) down-conversion, and (ii) surface plasmon resonance effect (iii) decreasing of the loss due to the reflection of the radiation, (iv) increasing of the reflection from the back contact, v) increasing of the effective solar cells surface, etc. The results demonstrate the possibility for to increasing of light harvesting, short circuit current and efficiency by application of nanomaterials in thin film and hetero-junction (HJ) solar cells. The first promising results allow an expectation for application of advanced nanomaterials in the 3d generation solar cells.

  7. A futuristic approach towards interface layer modifications for improved efficiency in inverted organic solar cells

    SciTech Connect

    Tiwari, J. P. E-mail: tiwarijp@mail.nplindia.org; Ali, Farman; Sharma, Abhishek; Chand, Suresh; Pillai, Sriraj; Parakh, Sonal

    2014-01-27

    Inverted polymer Solar Cells of the classical poly (3-hexylthiophene) (P3HT):(6,6)-phenyl-C{sub 61}butyric acid methyl ester (PC{sub 61}BM) blend on indium tin oxide substrates were fabricated, which shows improved device performance, by using a facile solution–processed ZnO-polyelectrolytes [poly (diallyldimethylammonium chloride) (PDADMAC), Poly (acrylic acid sodium salt) (PAS), poly (4-styrenesulfonic acid) (PSS), and Polyvinylpyrrolidone (PVP)] nanocomposite as a cathode interface layer compared to devices using pristine ZnO as cathode buffer layer in ambient conditions. The devices with different combinations of polyelectrolyte with ZnO show different improvements in the device efficiency. The combinations of ZnO with PVP and PDADMAC show highest amount of improvements in the efficiency by a factor of ∼17–19. The improvement of the efficiency may be due to various phenomena, such as the passivation of ZnO surface as well as bulk traps, work function modification, improved energy level alignment, improved electronic coupling of the inorganic/organic interface, improved light harvesting, and decrease of surface as well as bulk charge recombination in the device. The introduction of polyelectrolyte into ZnO inhibits the aggregation of ZnO nanoparticles yielding the large area ZnO nanoclusters; and hence, forming the uniform film of ZnO resulting in the modifications of morphology as well as electronic structure of ZnO-polyelectrolyte nano-composite favouring better electronic coupling between cathode and active layer and hence enhancing the current and, consequently, the efficiency. This simple low temperature ZnO-polyelectrolyte nanocomposite based protocol proposed for cathode interface layer modification may be very much useful for roll to roll industrial manufacturing of organic solar cells.

  8. A futuristic approach towards interface layer modifications for improved efficiency in inverted organic solar cells

    NASA Astrophysics Data System (ADS)

    Tiwari, J. P.; Pillai, Sriraj; Parakh, Sonal; Ali, Farman; Sharma, Abhishek; Chand, Suresh

    2014-01-01

    Inverted polymer Solar Cells of the classical poly (3-hexylthiophene) (P3HT):(6,6)-phenyl-C61butyric acid methyl ester (PC61BM) blend on indium tin oxide substrates were fabricated, which shows improved device performance, by using a facile solution-processed ZnO-polyelectrolytes [poly (diallyldimethylammonium chloride) (PDADMAC), Poly (acrylic acid sodium salt) (PAS), poly (4-styrenesulfonic acid) (PSS), and Polyvinylpyrrolidone (PVP)] nanocomposite as a cathode interface layer compared to devices using pristine ZnO as cathode buffer layer in ambient conditions. The devices with different combinations of polyelectrolyte with ZnO show different improvements in the device efficiency. The combinations of ZnO with PVP and PDADMAC show highest amount of improvements in the efficiency by a factor of ˜17-19. The improvement of the efficiency may be due to various phenomena, such as the passivation of ZnO surface as well as bulk traps, work function modification, improved energy level alignment, improved electronic coupling of the inorganic/organic interface, improved light harvesting, and decrease of surface as well as bulk charge recombination in the device. The introduction of polyelectrolyte into ZnO inhibits the aggregation of ZnO nanoparticles yielding the large area ZnO nanoclusters; and hence, forming the uniform film of ZnO resulting in the modifications of morphology as well as electronic structure of ZnO-polyelectrolyte nano-composite favouring better electronic coupling between cathode and active layer and hence enhancing the current and, consequently, the efficiency. This simple low temperature ZnO-polyelectrolyte nanocomposite based protocol proposed for cathode interface layer modification may be very much useful for roll to roll industrial manufacturing of organic solar cells.

  9. Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging.

    PubMed

    Pedersen, E B L; Angmo, D; Dam, H F; Thydén, K T S; Andersen, T R; Skjønsfjell, E T B; Krebs, F C; Holler, M; Diaz, A; Guizar-Sicairos, M; Breiby, D W; Andreasen, J W

    2015-08-28

    Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced. PMID:26220159

  10. Improvement in efficiency of micromorph tandem silicon solar cells by designing proper interfaces.

    PubMed

    Shen, Xiangqian; Wang, Qingkang; Wangyang, Peihua; Huang, Kun; Chen, Le; Liu, Daiming

    2015-11-15

    Efficient light management for micromorph tandem solar cells is achieved in this Letter by the combined application of TiO(2) and SiO(x) interlayers. Here, TiO(2) is incorporated into a ZnO/a-Si interface as an antireflection layer and SiO(x) is incorporated into an a-Si/μc-Si interface as an intermediate reflecting layer. Solar cells with such architecture not only increase the light absorption but also reduce the mismatch losses of current between the top and bottom cells. The key results, as evidenced by the spectral response measurements, are that the total photocurrent increases from 22.62 to 24.35 mA/cm(2), as well as the short circuit current density of the two component cells is reached to a delicate balance. The influences of the interlayer thickness and morphology on the improvement have been investigated using an electromagnetic simulation in order to take full advantage of this design. PMID:26565829

  11. Improved performance of microcrystalline silicon solar cell with graded-band-gap silicon oxide buffer layer

    NASA Astrophysics Data System (ADS)

    Shi, Zhen-Liang; Ji, Yun; Yu, Wei; Yang, Yan-Bin; Cong, Ri-Dong; Chen, Ying-Juan; Li, Xiao-Wei; Fu, Guang-Sheng

    2015-07-01

    Microcrystalline silicon (μc-Si:H) solar cell with graded band gap microcrystalline silicon oxide (μc-SiOx:H) buffer layer is prepared by plasma enhanced chemical vapor deposition and exhibits improved performance compared with the cell without it. The buffer layer moderates the band gap mismatch by reducing the barrier of the p/i interface, which promotes the nucleation of the i-layer and effectively eliminates the incubation layer, and then enhances the collection efficiency of the cell in the short wavelength region of the spectrum. The p/i interface defect density also decreases from 2.2 × 1012 cm-2 to 5.0 × 1011 cm-2. This graded buffer layer allows to simplify the deposition process for the μc-Si:H solar cell application. Project supported by the Key Basic Research Project of Hebei Province, China (Grant Nos. 12963930D and 12963929D), the Natural Science Foundation of Hebei Province, China (Grant Nos. F2013201250 and E2012201059), and the Science and Technology Research Projects of the Education Department of Hebei Province, China (Grant No. ZH2012030).

  12. Improvement of organic solar cells by flexible substrate and ITO surface treatments

    NASA Astrophysics Data System (ADS)

    Cheng, Yuang-Tung; Ho, Jyh-Jier; Wang, Chien-Kun; Lee, William; Lu, Chih-Chiang; Yau, Bao-Shun; Nain, Jhen-Liang; Chang, Shun-Hsyung; Chang, Chiu-Cheng; Wang, Kang L.

    2010-10-01

    In this paper, surface treatments on polyethylene terephthalate with polymeric hard coating (PET-HC) substrates are described. The effect of the contact angle on the treatment is first investigated. It has been observed that detergent is quite effective in removing organic contamination on the flexible PET-HC substrates. Next, using a DC-reactive magnetron sputter, indium tin oxide (ITO) thin films of 90 nm are grown on a substrate treated by detergent. Then, various ITO surface treatments are made for improving the performance of the finally developed organic solar cells with structure Al/P3HT:PCBM/PEDOT:PSS/ITO/PET. It is found that the parameters of the ITO including resistivity, carrier concentration, transmittance, surface morphology, and work function depended on the surface treatments and significantly influence the solar cell performance. With the optimal conditions for detergent treatment on flexible PET substrates, the ITO film with a resistivity of 5.6 × 10 -4 Ω cm and average optical transmittance of 84.1% in the visible region are obtained. The optimal ITO surface treated by detergent for 5 min and then by UV ozone for 20 min exhibits the best WF value of 5.22 eV. This improves about 8.30% in the WF compared with that of the untreated ITO film. In the case of optimal treatment with the organic photovoltaic device, meanwhile, 36.6% enhancement in short circuit current density ( Jsc) and 92.7% enhancement in conversion efficiency ( η) over the untreated solar cell are obtained.

  13. Towards a CdS/Cu2ZnSnS4 solar cell efficiency improvement: A theoretical approach

    NASA Astrophysics Data System (ADS)

    Courel, Maykel; Andrade-Arvizu, J. A.; Vigil-Galán, O.

    2014-12-01

    In this work, a device model for Cu2ZnSnS4 (CZTS) solar cell with certified world record efficiency is presented. A study of the most important loss mechanisms and its effect on solar cell performance was carried out. The trap-assisted tunneling and CdS/CZTS interface recombination are introduced as the most important loss mechanisms. Detailed comparison of the simulation results to the measured device parameters shows that our model is able to reproduce the experimental observations (quantum efficiency, efficiency, Jsc, FF, and Voc) reported under normal operating conditions. Finally, a discussion about a further solar cell efficiency improvement is addressed.

  14. Improved hole-transporting property via HAT-CN for perovskite solar cells without lithium salts.

    PubMed

    Ma, Yingzhuang; Chung, Yao-Hsien; Zheng, Lingling; Zhang, Danfei; Yu, Xiao; Xiao, Lixin; Chen, Zhijian; Wang, Shufeng; Qu, Bo; Gong, Qihuang; Zou, Dechun

    2015-04-01

    A nonadditive hole-transporting material (HTM) of a triphenylamine derivative of N,N'-di(3-methylphenyl)-N,N'-diphenyl-4,4'-diaminobiphenyl (TPD) is used for the organic-inorganic hybrid perovskite solar cells. The power conversion efficiency (PCE) can be significantly enhanced by inserting a thin layer of 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) without adding an ion additive because the hole-transporting properties improve. The short-circuit current density (J(sc)) increases from 8.5 to 13.1 mA/cm(2), the open-circuit voltage (V(oc)) increases from 0.84 to 0.92 V, and the fill-factor (FF) increases from 0.45 to 0.59, which corresponds to the increase in PCE from 3.2% to 7.1%. Moreover, the PCE decreases by only 10% after approximately 1000 h without encapsulation, which suggests an alternative method to improve the stability of perovskite solar cells. PMID:25761404

  15. Improving performance of inverted organic solar cells using ZTO nanoparticles as cathode buffer layer

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Yen; Cheng, Wen-Hui; Jeng, Jiann-Shing; Chen, Jen-Sue

    2016-06-01

    In this study, a low-temperature solution-processed zinc tin oxide (ZTO) films are successfully utilized as the cathode buffer layer in the inverted organic P3HT:PCBM bulk heterojunction solar cells. ZTO film cathode buffer layer with an appropriate Sn-doping concentration outperforms the zinc oxide (ZnO) film with an improved power conversion efficiency (1.96% (ZTO film) vs. 1.56% (ZnO film)). Furthermore, ZTO nanoparticles (NPs) are also synthesized via low-temperature solution route and the device with ZTO NPs buffer layer exhibits a significant improvement in device performance to reach a PCE of 2.60%. The crystallinity of the cathode buffer layer plays an influential factor in the performance. From impedance spectroscopy analysis, a correlation between short circuit current (Jsc), carrier life time (τavg) and, thus, PCE is observed. The interplay between composition and crystallinity of the cathode buffer layers is discussed to find their influences on the solar cell performance.

  16. New Fabrication Method Improves the Efficiency and Economics of Solar Cells (Fact Sheet)

    SciTech Connect

    Not Available

    2012-07-01

    Synthetic fabrication strategy optimizes the illumination geometry and transport properties of dye-sensitized solar cells. Using oriented titanium oxide (TiO{sub 2}) nanotube (NT) arrays has shown promise for dye-sensitized solar cells (DSSCs). High solar conversion efficiency requires that the incident light enters the cell from the photoelectrode side. However, for NT-based DSSCs, the light normally enters the cell through the counter electrode because a nontransparent titanium foil is typically used as the substrate for forming the aligned NTs and for making electrical contact with them. It has been synthetically challenging to prepare transparent TiO{sub 2} NT electrodes by directly anodizing Ti metal films on transparent conducting oxide (TCO) substrates because it is difficult to control the synthetic conditions. National Renewable Energy Laboratory (NREL) researchers have developed a general synthetic strategy for fabricating transparent TiO{sub 2} NT films on TCO substrates. With the aid of a conducting Nb-doped TiO{sub 2} (NTO) layer between the Ti film and TCO substrate, the Ti film can be anodized completely without degrading the TCO. The NTO layer protects the TCO from degradation through a self-terminating mechanism by arresting the electric field-assisted dissolution process at the NT-NTO interface. NREL researchers found that the illumination direction and wavelength of the light incident on the DSSCs strongly influenced the incident photon-to-current conversion efficiency, light-harvesting, and charge-collection properties, which, in turn, affect the photocurrent density, photovoltage, and solar energy conversion efficiency. Researchers also examined the effects of NT film thickness on the properties and performance of DSSCs and found that illuminating the cell from the photoelectrode side substantially increased the conversion efficiency compared with illuminating it from the counter-electrode side. This method solves a key challenge in fabricating

  17. Solar cell modules with improved backskin and methods for forming same

    DOEpatents

    Hanoka, Jack I.

    1998-04-21

    A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the module for contacting the first surface of the front support layer to form an edge seal. A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the

  18. Nanosphere lithography for improved absorption in thin crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Chang, Yuanchih; Payne, David N. R.; Pollard, Michael E.; Pillai, Supriya; Bagnall, Darren M.

    2015-12-01

    Over the last decade, plasmonic nanoparticle arrays have been extensively studied for their light trapping potential in thin film solar cells. However, the commercial use of such arrays has been limited by complex and expensive fabrication techniques such as e-beam lithography. Nanosphere lithography (NSL) is a promising low-cost alternative for forming regular arrays of nanoscale features. Here, we use finite-difference time-domain (FDTD) simulations to determine the optical enhancement due to nanosphere arrays embedded at the rear of a complete thin film device. Array parameters including the nanosphere pitch and diameter are explored, with the FDTD model itself first validated by comparing simulations of Ag nanodisc arrays with optical measurements of pre-existing e-beam fabricated test structures. These results are used to guide the development of a nanosphere back-reflector for 20 μm thin crystalline silicon cells. The deposition of polystyrene nanosphere monolayers is optimized to provide uniform arrays, which are subsequently incorporated into preliminary, proof of concept device structures. Absorption and photoluminescence measurements clearly demonstrate the potential of nanosphere arrays for improving the optical response of a solar cell using economical and scalable methods.

  19. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers

    NASA Astrophysics Data System (ADS)

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang (Michael); Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiOx and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiOx/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%.

  20. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers.

    PubMed

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang Michael; Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiO(x) and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiO(x)/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%. PMID:26457966

  1. Flattened light-scattering substrate in thin film silicon solar cells for improved infrared response

    NASA Astrophysics Data System (ADS)

    Sai, Hitoshi; Kanamori, Yoshiaki; Kondo, Michio

    2011-03-01

    Surface texturing is a technique commonly used to enhance light absorption in thin film silicon solar cells; it should be noted that highly textured substrates often induce structural defects in the active layer, which deteriorates the photovoltaic performance. In this paper, we propose a flattened light-scattering substrate (FLiSS) with a large refractive index contrast in plane as an approach to overcome this trade-off. A FLiSS composed of a two-dimensional ZnO grating and a Ag reflector is applied to μc-Si:H cells, in order to improve the spectral response in the infrared region while maintaining a high VOC and FF.

  2. Unravelling the working junction of aqueous-processed polymer-nanocrystal solar cells towards improved performance.

    PubMed

    Chen, Zhaolai; Du, Xiaohang; Jin, Gan; Zeng, Qingsen; Liu, Fangyuan; Yang, Bai

    2016-06-21

    Hybrid solar cells (HSCs) based on aqueous polymers and nanocrystals are attractive due to their environmental friendliness and cost effectiveness. In this study, HSCs are fabricated from a series of water-soluble polymers with different highest occupied molecular orbital (HOMO) levels and nanocrystals with different Fermi levels. We demonstrate that the working principle of the aqueous-processed HSCs follows a p-n junction instead of a type-II heterojunction. The function of the polymer is to provide an interface dipole which can improve the build-in potential of the HSCs. Subsequently, the aqueous-processed HSCs are optimized following a p-n junction and an improved PCE of 5.41% is achieved, which is the highest for aqueous-processed HSCs. This study will provide instructive guidelines for the development of aqueous-processed HSCs. PMID:27229447

  3. Improved dye-sensitized solar cells by composite ionic liquid electrolyte incorporating layered titanium phosphate

    SciTech Connect

    Cheng, Ping; Lan, Tian; Wang, Wanjun; Wu, Haixia; Yang, Haijun; Guo, Shouwu

    2010-05-15

    We reported a composite electrolyte prepared by incorporating layered {alpha}-titanium phosphate ({alpha}-TiP) into a binary ionic liquid of 1-propyl-3-methylimidazolium iodide (PMII) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF{sub 4}) (volume ratio, 13:7) electrolyte. The addition of {alpha}-TiP markedly improved the photovoltaic properties of dye-sensitized solar cells (DSSCs) compared to that without {alpha}-TiP. The enhancement was explained by improved diffusion of tri-iodide (I{sub 3}{sup -}) ions, suppressed electron recombination with I{sub 3}{sup -} in the electrolyte and increased lifetime of electrons in mesoscopic TiO{sub 2} film. (author)

  4. Modified surface loading process for achieving improved performance of the quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Jin, Zhongxiu; Zhu, Jun; Xu, Yafeng; Zhou, Li; Dai, Songyuan

    2016-06-01

    Achieving high surface coverage of the colloidal quantum dots (QDs) on TiO2 films has been challenging for quantum dot-sensitized solar cells (QDSCs). Herein, a general surface engineering approach was proposed to increase the loading of these QDs. It was found that S2- treatment/QD re-uptake process can significantly improve the attachment of the QDs on TiO2 films. Surface concentration of the QDs was improved by ∼60%, which in turn greatly enhances light absorption and decreases carrier recombination in QDSCs. Ensuing QDSCs with optimized QD loading exhibit a power conversion efficiency of 3.66%, 83% higher than those fabricated with standard procedures.

  5. A study of improvements in silicon solar cell efficiency due to various geometrical and doping modifications

    NASA Technical Reports Server (NTRS)

    Dunbar, P. M.; Hauser, J. R.

    1976-01-01

    This paper presents the results of continued studies of silicon solar cell operation and limitations. The objective of this paper is to report on geometrical and doping changes in silicon solar cells which result in predictions of high efficiencies. Efficiencies as high as 20 per cent (uncorrected for metal coverage and ohmic sheet resistance) have been calculated for optimized cells. The conditions required to achieve these efficiency values are discussed.

  6. Acetate Salts as Nonhalogen Additives To Improve Perovskite Film Morphology for High-Efficiency Solar Cells.

    PubMed

    Wu, Qiliang; Zhou, Pengcheng; Zhou, Weiran; Wei, Xiangfeng; Chen, Tao; Yang, Shangfeng

    2016-06-22

    A two-step method has been popularly adopted to fabricate a perovskite film of planar heterojunction organo-lead halide perovskite solar cells (PSCs). However, this method often generates uncontrollable film morphology with poor coverage. Herein, we report a facile method to improve perovskite film morphology by incorporating a small amount of acetate (CH3COO(-), Ac(-)) salts (NH4Ac, NaAc) as nonhalogen additives in CH3NH3I solution used for immersing PbI2 film, resulting in improved CH3NH3PbI3 film morphology. Under the optimized NH4Ac additive concentration of 10 wt %, the best power conversion efficiency (PCE) reaches 17.02%, which is enhanced by ∼23.2% relative to that of the pristine device without additive, whereas the NaAc additive does not lead to an efficiency enhancement despite the improvement of the CH3NH3PbI3 film morphology. SEM study reveals that NH4Ac and NaAc additives can both effectively improve perovskite film morphology by increasing the surface coverage via diminishing pinholes. The improvement on CH3NH3PbI3 film morphology is beneficial for increasing the optical absorption of perovskite film and improving the interfacial contact at the perovskite/spiro-OMeTAD interface, leading to the increase of short-circuit current and consequently efficiency enhancement of the PSC device for NH4Ac additive only. PMID:27253082

  7. Improved radiation resistant properties of electron irradiated c-Si solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Khuram; Khan, Sohail A.; MatJafri, M. Z.

    2016-08-01

    This work investigates the radiation tolerance of c-Si solar cells under electron energy of 9 MeV with fluence of 5.09×1016 cm-2. The solar cells were fabricated and characterized before and after electron irradiation through current-voltage (I-V), capacitance-voltage (C-V), and frequency dependent conductance (Gp) measurements. The results revealed that all the output parameters such as short circuit current (Isc), open circuit voltage (Voc), series resistance (Rs), and efficiency (η) were degraded after electron irradiation. Capacitance-Voltage measurements show that there is a slight decrease in the base carrier concentration (ND), while a small increase in depletion layer width (WD) was due to an increase in the base carrier concentration. Enhancements in the density of interface states (Nss), and trap time constant (τ) have been observed after electron irradiation. The results has revealed that back surface field (BSF) solar cell with front surface passivation (FSP) presented lowest efficiency degradation ratio of 11.3% as compared to 15.3% of the solar cell without FSP. The subsequent annealing of irradiated Si solar cell devices revealed that the Si solar cell with FSP demonstrated high efficiency recovery ratio of 94% as compared to non-FSP solar cell.

  8. Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging

    NASA Astrophysics Data System (ADS)

    Pedersen, E. B. L.; Angmo, D.; Dam, H. F.; Thydén, K. T. S.; Andersen, T. R.; Skjønsfjell, E. T. B.; Krebs, F. C.; Holler, M.; Diaz, A.; Guizar-Sicairos, M.; Breiby, D. W.; Andreasen, J. W.

    2015-08-01

    Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced.Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing

  9. Role of hydrogen plasma pretreatment in improving passivation of the silicon surface for solar cells applications.

    PubMed

    Wang, Fengyou; Zhang, Xiaodan; Wang, Liguo; Jiang, Yanjian; Wei, Changchun; Sun, Jian; Zhao, Ying

    2014-09-10

    We have investigated the role of hydrogen plasma pretreatment in promoting silicon surface passivation, in particular examining its effects on modifying the microstructure of the subsequently deposited thin hydrogenated amorphous silicon (a-Si:H) passivation film. We demonstrate that pretreating the silicon surface with hydrogen plasma for 40 s improves the homogeneity and compactness of the a-Si:H film by enhancing precursor diffusion and thus increasing the minority carrier lifetime (τ(eff)). However, excessive pretreatment also increases the density of dangling bond defects on the surface due to etching effects of the hydrogen plasma. By varying the duration of hydrogen plasma pretreatment in fabricating silicon heterojunction solar cells based on textured substrates, we also demonstrate that, although the performance of the solar cells shows a similar tendency to that of the τ(eff) on polished wafers, the optimal duration is prolonged owing to the differences in the surface morphology of the substrates. These results suggest that the hydrogen plasma condition must be carefully regulated to achieve the optimal level of surface atomic hydrogen coverage and avoid the generation of defects on the silicon wafer. PMID:25141300

  10. Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance

    NASA Astrophysics Data System (ADS)

    Desta, Derese; Ram, Sanjay K.; Rizzoli, Rita; Bellettato, Michele; Summonte, Caterina; Jeppesen, Bjarke R.; Jensen, Pia B.; Tsao, Yao-Chung; Wiggers, Hartmut; Pereira, Rui N.; Balling, Peter; Larsen, Arne Nylandsted

    2016-06-01

    A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering. The n-i-p amorphous silicon thin-film solar cells grown on such a back-reflector show enhanced light absorption resulting in improved external quantum efficiency. The benefit of the light trapping in those solar cells is evidenced by the gains in short-circuit current density and efficiency up to 15.6% and 19.3% respectively, compared to the reference flat solar cells. This improvement in the current generation in the solar cells grown on the flat-topped (buried pyramid) back-reflector is observed even when the irradiation takes place at large oblique angles of incidence. Finite-difference-time-domain simulation results of optical absorption and ideal short-circuit current density values agree well with the experimental findings. The proposed approach uses a low cost and simple fabrication technique and allows effective light manipulation by utilizing the optical properties of micro-scale structures and nanoscale constituent particles.

  11. Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance.

    PubMed

    Desta, Derese; Ram, Sanjay K; Rizzoli, Rita; Bellettato, Michele; Summonte, Caterina; Jeppesen, Bjarke R; Jensen, Pia B; Tsao, Yao-Chung; Wiggers, Hartmut; Pereira, Rui N; Balling, Peter; Larsen, Arne Nylandsted

    2016-06-01

    A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering. The n-i-p amorphous silicon thin-film solar cells grown on such a back-reflector show enhanced light absorption resulting in improved external quantum efficiency. The benefit of the light trapping in those solar cells is evidenced by the gains in short-circuit current density and efficiency up to 15.6% and 19.3% respectively, compared to the reference flat solar cells. This improvement in the current generation in the solar cells grown on the flat-topped (buried pyramid) back-reflector is observed even when the irradiation takes place at large oblique angles of incidence. Finite-difference-time-domain simulation results of optical absorption and ideal short-circuit current density values agree well with the experimental findings. The proposed approach uses a low cost and simple fabrication technique and allows effective light manipulation by utilizing the optical properties of micro-scale structures and nanoscale constituent particles. PMID:27244247

  12. Nanocrystal Solar Cells

    SciTech Connect

    Gur, Ilan

    2006-12-15

    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.

  13. Efficiency Improvement of Crystalline Solar Cells: Final Subcontract Report, 1 January 2002 - 30 September 2006

    SciTech Connect

    Weber, E. R.

    2007-11-01

    UC-Berkeley study of transition metal related defects in PV-grade mc-Si to understand their pathways into solar cells; chemical state/distribution; interaction with structural defects; defect engineering.

  14. Pulsed laser deposition of Mn doped CdSe quantum dots for improved solar cell performance

    SciTech Connect

    Dai, Qilin; Wang, Wenyong E-mail: jtang2@uwyo.edu; Tang, Jinke E-mail: jtang2@uwyo.edu; Sabio, Erwin M.

    2014-05-05

    In this work, we demonstrate (1) a facile method to prepare Mn doped CdSe quantum dots (QDs) on Zn{sub 2}SnO{sub 4} photoanodes by pulsed laser deposition and (2) improved device performance of quantum dot sensitized solar cells of the Mn doped QDs (CdSe:Mn) compared to the undoped QDs (CdSe). The band diagram of photoanode Zn{sub 2}SnO{sub 4} and sensitizer CdSe:Mn QD is proposed based on the incident-photon-to-electron conversion efficiency (IPCE) data. Mn-modified band structure leads to absorption at longer wavelengths than the undoped CdSe QDs, which is due to the exchange splitting of the CdSe:Mn conduction band by the Mn dopant. Three-fold increase in the IPCE efficiency has also been observed for the Mn doped samples.

  15. Improve the operational stability of the inverted organic solar cells using bilayer metal oxide structure.

    PubMed

    Chang, Jingjing; Lin, Zhenhua; Jiang, Changyun; Zhang, Jie; Zhu, Chunxiang; Wu, Jishan

    2014-11-12

    Operational stability is a big obstacle for the application of inverted organic solar cells (OSCs), however, less talked about in the research reports. Due to photoinduced degradation of the metal oxide interlayer, which can cause shunts generation and degeneration in ZnO interlayer, a significant degradation of open circuit voltage (Voc) and fill factor (FF) has been observed by in situ periodic measurements of the device current density-voltage (J-V) curves with light illumination. By combining TiOx and ZnO to form bilayer structures on ITO, the photovoltaic performance is improved and the photoinduced degradation is reduced. It was found that the device based on ZnO/TiOx bilayer structure achieved better operational stability as compared to that with ZnO or TiOx interlayer. PMID:25299062

  16. 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.

  17. Simulation of high-efficiency n[sup +]p indium phosphide solar cell results and future improvements

    SciTech Connect

    Jain, R.K.; Flood, D.J. )

    1994-12-01

    A simulation of the highest efficiency (19.1% AM0) n[sup +]p indium phosphide (InP) solar cell was made using a computer code PC-1D in order to understand it and suggest future improvements to it. Available cell design and process data was used in the simulation. Minority carrier diffusion lengths in the emitter and base have been varied to match the experimental cell I-V characteristics with the calculated results. To further understand and improve the InP cell efficiency, simulations were performed using improved values of cell material and process parameters. The authors show that the efficiency of this cell could be increased to more than 23% AM0 by incorporating the suggested cell material, design and process improvements. At these high efficiencies InP cell technology will be very attractive for space use.

  18. Improving solar cell efficiencies by up-conversion of sub-band-gap light

    NASA Astrophysics Data System (ADS)

    Trupke, T.; Green, M. A.; Würfel, P.

    2002-10-01

    A system for solar energy conversion using the up-conversion of sub-band-gap photons to increase the maximum efficiency of a single-junction conventional, bifacial solar cell is discussed. An up-converter is located behind a solar cell and absorbs transmitted sub-band-gap photons via sequential ground state absorption/excited state absorption processes in a three-level system. This generates an excited state in the up-converter from which photons are emitted which are subsequently absorbed in the solar cell and generate electron-hole pairs. The solar energy conversion efficiency of this system in the radiative limit is calculated for different cell geometries and different illumination conditions using a detailed balance model. It is shown that in contrast to an impurity photovoltaic solar cell the conditions of photon selectivity and of complete absorption of high-energy photons can be met simultaneously in this system by restricting the widths of the bands in the up-converter. The upper limit of the energy conversion efficiency of the system is found to be 63.2% for concentrated sunlight and 47.6% for nonconcentrated sunlight.

  19. Application of Vacancy Injection Gettering to Improve Efficiency of Solar Cells Produced by Millinet Solar: Cooperative Research and Development Final Report, CRADA Number CRD-10-417

    SciTech Connect

    Sopori, B.

    2012-07-01

    NREL will apply vacancy injection gettering (VIG) to Millinet solar cells and evaluate the performance improvement produced by this process step. The VIG will be done in conjunction with the formation of a back, Al-alloyed, contact. Millinet Solar will provide NREL with cells having AR coating on the front side and screen-printed Al on the backside, which will be processed in the NREL's optical furnace to perform simultaneous VIG and back contact alloying with deep BSF. These cells will be sent back to Millinet solar for a screen-printed front/side contact mask, followed by a second firing at NREL. Detailed analyses will be performed to determine improvements due to BSF and VIG.

  20. Improved light trapping in microcrystalline silicon solar cells by plasmonic back reflector with broad angular scattering and low parasitic absorption

    NASA Astrophysics Data System (ADS)

    Tan, Hairen; Sivec, Laura; Yan, Baojie; Santbergen, Rudi; Zeman, Miro; Smets, Arno H. M.

    2013-04-01

    We show experimentally that the photocurrent of thin-film hydrogenated microcrystalline silicon (μc-Si:H) solar cells can be enhanced by 4.5 mA/cm2 with a plasmonic back reflector (BR). The light trapping performance is improved using plasmonic BR with broader angular scattering and lower parasitic absorption loss through tuning the size of silver nanoparticles. The μc-Si:H solar cells deposited on the improved plasmonic BR demonstrate a high photocurrent of 26.3 mA/cm2 which is comparable to the state-of-the-art textured Ag/ZnO BR. The commonly observed deterioration of fill factor is avoided by using μc-SiOx:H as the n-layer for solar cells deposited on plasmonic BR.

  1. Polymer Solar Cells: Understanding Solvent Interactions and Morphology, and Strategies for Efficiency Improvements

    NASA Astrophysics Data System (ADS)

    Chang, Lilian

    Organic solar cells have the potential to be unrivaled in terms of processing cost, speed, and simplicity. The simplest of such devices consists of a single bulk-heterojunction (BHJ) active layer, in which the electron donor (conjugated polymer) and electron acceptor (fullerene) are deposited from a common solvent. The performance of BHJ solar cells is strongly correlated with the nanoscale structure of the active layer. Various processing techniques have been explored to improve the nanoscale morphology of the BHJ layer, e.g. by varying the casting solvent, thermal annealing, solvent annealing, and solvent additives. An understanding of the role of residual solvent in the BHJ layer is imperative in order to develop strategies for morphology stabilization and preserve the longevity of the device. This work highlights the effect of residual solvents on acceptor, (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) diffusion and ultimately the stability of the morphology. We first show that solvent is retained within the BHJ film despite prolonged heat treatment, leading to extensive phase separation between poly(3-hexylthiophene) (P3HT) and PCBM. We then show that the addition of a small volume fraction of nitrobenzene to the casting solution inhibits the diffusion of PCBM in the film and improves the fill factor of the BHJ device without further tempering. Other commonly used additives for morphology improvement were also investigated, i.e. 1,8-diiodooctane and 1-chloronaphthalene. We show that the choice of solvent additives has direct implications on morphological evolution, i.e. P3HT:PCBM BHJ films processed with a small amount of 1,8-diiodooctane or 1-chloronaphthalene have more crystalline PCBM domains compared to crystalline P3HT domains, while the opposite is true for films cast with nitrobenzene additive and films cast purely from chlorobenzene. The BHJ film cross-links when annealed at 300°C in the presence of 1,8-diiodooctane. Cross-linking is found to

  2. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode

    NASA Astrophysics Data System (ADS)

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-01

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PEDOT:PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  3. Efficiency improvement of flexible a-SiGe:H solar cells decorated by SiNx composite nanostructures

    NASA Astrophysics Data System (ADS)

    Wang, Yanyan; Ye, Xiaojun; Zhu, Jian; Zhang, Zhen; Yang, Junkun; Wu, Xuemei; Qiu, Bocang; Zhang, Ruiying

    2015-05-01

    We report on the experimental demonstration of the efficiency improvement of flexible a-SiGe:H solar cells decorated by SiNx composite nanostructures. The structures, which are composed of SiNx nanodome structures and a thin SiNx film that is underneath the nanodome structures, were implemented via sequential processes using inductance-coupled plasma chemical vapor deposition (ICP-CVD), nanosphere lithography (NSL), and reactive ion etching (RIE). Compared with the a-SiGe:H solar cells without the SiNx composite nanostructures, solar cells with SiNx composite nanostructures exhibit that the surface reflectivity reduces down to less than 5% over the spectrum range of 200-700 nm, and the open circuit voltage (Voc) and fill factor (FF) increase up to 0.76 V from 0.70 V and 52.4% from 38.4% respectively, although the short circuit current density (Jsc) reduces down to 11.6 mA/cm2 from 14.7 mA/cm2. The improvement for Voc and FF indicates that a-SiGe:H solar cells were well passivated by using such SiNx composite structures, which results in the overall enhancement of the conversion efficiency from 4.38% to 5.13% finally. If the absorption of the dielectric composite nanostructures decreases, the higher conversion efficiency should be promisingly achieved in these Si-based thin film solar cells decorated by dielectric composite nanostructures.

  4. Optimization of oxidation processes to improve crystalline silicon solar cell emitters

    SciTech Connect

    Shen, L.; Liang, Z. C. Liu, C. F.; Long, T. J.; Wang, D. L.

    2014-02-15

    Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 Ω/□ performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 Ω/□ that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 10{sup 20} cm{sup −3} and 7.78 × 10{sup 20} cm{sup −3} and with junction depths between 0.46 μm and 0.55 μm possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%{sub abs} compared to conventional emitters with 50 Ω/□ sheet resistance.

  5. Improved defect analysis of Gallium Arsenide solar cells using image enhancement

    NASA Technical Reports Server (NTRS)

    Kilmer, Louis C.; Honsberg, Christiana; Barnett, Allen M.; Phillips, James E.

    1989-01-01

    A new technique has been developed to capture, digitize, and enhance the image of light emission from a forward biased direct bandgap solar cell. Since the forward biased light emission from a direct bandgap solar cell has been shown to display both qualitative and quantitative information about the solar cell's performance and its defects, signal processing techniques can be applied to the light emission images to identify and analyze shunt diodes. Shunt diodes are of particular importance because they have been found to be the type of defect which is likely to cause failure in a GaAs solar cell. The presence of a shunt diode can be detected from the light emission by using a photodetector to measure the quantity of light emitted at various current densities. However, to analyze how the shunt diodes affect the quality of the solar cell the pattern of the light emission must be studied. With the use of image enhancement routines, the light emission can be studied at low light emission levels where shunt diode effects are dominant.

  6. Circle chain embracing donor-acceptor organic dye: simultaneous improvement of photocurrent and photovoltage for dye-sensitized solar cells.

    PubMed

    Liu, Jian; Numata, Youhei; Qin, Chuanjiang; Islam, Ashraful; Yang, Xudong; Han, Liyuan

    2013-09-01

    We demonstrate for the first time that employing a circle chain embracing π-conjugated backbone is a promising strategy to construct superior organic sensitizers for dye-sensitized solar cells (DSCs), with simultaneous improvement of photocurrent and photovoltage. A DSC based on one circle chain embracing dye produced a high conversion efficiency of 8.34%. PMID:23604204

  7. Improvement of Charge Transportation in Si Quantum Dot-Sensitized Solar Cells Using Vanadium Doped TiO2.

    PubMed

    Seo, Hyunwoong; Ichida, Daiki; Hashimoto, Shinji; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Nam, Sang-Hun; Boo, Jin-Hyo

    2016-05-01

    The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells. PMID:27483838

  8. Moth-Eye TiO2 Layer for Improving Light Harvesting Efficiency in Perovskite Solar Cells.

    PubMed

    Kang, Seong Min; Jang, Segeun; Lee, Jong-Kwon; Yoon, Jungjin; Yoo, Dong-Eun; Lee, Jin-Wook; Choi, Mansoo; Park, Nam-Gyu

    2016-05-01

    A moth-eye nanostructured mp-TiO2 film using conventional lithography, nano-imprinting and polydimethyl-siloxane (PDMS) stamping methods is demonstrated for the first time. Power conversion efficiency of the moth-eye patterned perovskite solar cell is improved by ≈11%, which mainly results from increasing light harvesting efficiency by structural optical property. PMID:26990492

  9. Optimization of nanoparticle structure for improved conversion efficiency of dye solar cell

    SciTech Connect

    Mohamed, Norani Muti; Zaine, Siti Nur Azella

    2014-10-24

    Heavy dye loading and the ability to contain the light within the thin layer (typically ∼12 μm) are the requirement needed for the photoelectrode material in order to enhance the harvesting efficiency of dye solar cell. This can be realized by optimizing the particle size with desirable crystal structure. The paper reports the investigation on the dependency of the dye loading and light scattering on the properties of nanostructured photoelectrode materials by comparing 4 different samples of TiO{sub 2} in the form of nanoparticles and micron-sized TiO{sub 2} aggregates which composed of nanocrystallites. Their properties were evaluated by using scanning electron microscopy, X-ray diffraction and UVVis spectroscopy while the performance of the fabricated test cells were measured using universal photovoltaic test system (UPTS) under 1000 W/cm{sup 2} intensity of radiation. Nano sized particles provide large surface area which allow for greater dye adsorption but have no ability to retain the incident light in the TiO{sub 2} film. In contrast, micron-sized particles in the form of aggregates can generate light scattering allowing the travelling distance of the light to be extended and increasing the interaction between the photons and dye molecules adsorb on TiO{sub 2}nanocrystallites. This resulted in an improvement in the conversion efficiency of the aggregates that demonstrates the close relation between light scattering effect and the structure of the photolectrode film.

  10. Improved Efficiency of Silicon Nanoholes/Gold Nanoparticles/Organic Hybrid Solar Cells via Localized Surface Plasmon Resonance

    NASA Astrophysics Data System (ADS)

    Lu, Ronghua; Xu, Ling; Ge, Zhaoyun; Li, Rui; Xu, Jun; Yu, Linwei; Chen, Kunji

    2016-03-01

    Silicon is the most widely used material for solar cells due to its abundance, non-toxicity, reliability, and mature fabrication process. In this paper, we fabricated silicon nanoholes (SiNHS)/gold nanoparticles (AuNPS)/organic hybrid solar cells and investigated their spectral and opto-electron conversion properties. SiNHS nanocomposite films were fabricated by metal-assisted electroless etching (EE) method. Then, we modified the surface of the nanocomposite films by exposing the samples in the air. After that, polymer poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) blended with AuNPS were spin-coated on the surface of the SiNHS nanocomposite films as a hole-transporting layer. The external quantum efficiency (EQE) values of the solar cells with AuNPS are higher than that of the samples without AuNPS in the spectral region of 600-1000 nm, which were essential to achieve high performance photovoltaic cells. The power conversion efficiency (PCE) of the solar cells incorporating AuNPS exhibited an enhancement of 27 %, compared with that of the solar cells without AuNPS. We thought that the improved efficiency were attributed to localized surface plasmon resonance (LSPR) triggered by gold nanoparticles in SiNHS nanocomposite films.

  11. Performance and stability improvements for dye-sensitized solar cells in the presence of luminescent coatings

    NASA Astrophysics Data System (ADS)

    Bella, Federico; Griffini, Gianmarco; Gerosa, Matteo; Turri, Stefano; Bongiovanni, Roberta

    2015-06-01

    Here we present how the sunlight radiation incident on a dye-sensitized solar cell (DSSC) can be shifted of a few tens of nanometers by means of an economical, easy to prepare and multifunctional photocurable fluoropolymeric light-shifting (LS) coating, to achieve both improved efficiency and device stability. By the introduction of a very small amount of a luminescent agent in the LS coating, the down-shifting of near-UV photons to higher wavelengths easily harvestable by the organic dye of a DSSC is successfully demonstrated. This optical effect not only results in an over 60% improvement of the power conversion efficiency of DSSC devices, but the UV light filtering action promoted by the luminescent agent also provides protection to the photosensitive DSSC components. This aspect, combined with a potential thermal shielding effect and the easy-cleaning behavior imparted to the coating by its fluorinated nature, leads to excellent device stability as evidenced from an aging test performed outdoors under real operating conditions for more than 2000 h. Our study demonstrates that the use of light-cured multifunctional coatings with light management characteristics at the nanometer scale represents a new promising strategy to simultaneously increase the performance and durability of DSSC devices.

  12. Device lifetime improvement of polymer-based bulk heterojunction solar cells by incorporating copper oxide layer at Al cathode

    NASA Astrophysics Data System (ADS)

    Wang, Mingdong; Xie, Fangyan; Xie, Weiguang; Zheng, Shizhao; Ke, Ning; Chen, Jian; Zhao, Ni; Xu, J. B.

    2011-05-01

    Organic solar cells are commonly susceptible to degradation in air. We present that insertion of a thin layer of thermally evaporated copper oxide (CuOx) between the organic active layer and the Al cathode can greatly extend the lifetime of P3HT:PCBM based bulk heterojunction solar cells. The performance can be further improved by applying an interfacial bilayer of CuOx/LiF. Our results suggest that the CuOx functions not only as a charge transport layer but also as a protection layer, which prevents formation of thick organic-Al interdiffusion area. This leads to a more air-resistive cathode/organic interface.

  13. Plasmonic effects in ultrathin amorphous silicon solar cells: performance improvements with Ag nanoparticles on the front, the back, and both.

    PubMed

    Winans, Joshua D; Hungerford, Chanse; Shome, Krishanu; Rothberg, Lewis J; Fauchet, Philippe M

    2015-02-01

    Thin-film hydrogenated amorphous silicon (a-Si:H) solar cells that are free-standing over a 2x2 mm area have been fabricated with thicknesses of 150 nm, 100 nm, and 60 nm. Silver nanoparticles (NPs) created on the front and/or back surfaces of the solar cells led to improvement in performance measures such as current density, overall efficiency, and external quantum efficiency. The effect of changing silver nanoparticle size and incident light angle was tested. Finite-Difference Time-Domain simulations are presented as a way to understand the experimental results as well as guide future research efforts. PMID:25836257

  14. Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

    PubMed Central

    2014-01-01

    To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively. PMID:25276101

  15. Role of 2-D periodic symmetrical nanostructures in improving efficiency of thin film solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jiang, Liyong; Li, Xiangyin

    2016-01-01

    We systematically investigated several different nanostructures in crystalline silicon (c-Si) thin film solar cells and then proposed a brand-new structure with two dimensional (2-D) periodic dielectric cylinders on the top and annular metal columns on bottom surface to enhance the optical harvesting. The periodic symmetrical nanostructures affect the solar cell efficiency due to the grating diffraction effect of dielectric columns and surface plasmon polaritons (SPPs) effect induced by metal nanostructures at the dielectric-metal interface. About 52.1% more optical absorption and 33.3% more power conversion efficiency are obtained, and the maximum short current reaches to 33.24 mA/cm2.

  16. Substantial improvement of perovskite solar cells stability by pinhole-free hole transport layer with doping engineering

    PubMed Central

    Jung, Min-Cherl; Raga, Sonia R.; Ono, Luis K.; Qi, Yabing

    2015-01-01

    We fabricated perovskite solar cells using a triple-layer of n-type doped, intrinsic, and p-type doped 2,2′,7,7′-tetrakis(N,N′-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) (n-i-p) as hole transport layer (HTL) by vacuum evaporation. The doping concentration for n-type doped spiro-OMeTAD was optimized to adjust the highest occupied molecular orbital of spiro-OMeTAD to match the valence band maximum of perovskite for efficient hole extraction while maintaining a high open circuit voltage. Time-dependent solar cell performance measurements revealed significantly improved air stability for perovskite solar cells with the n-i-p structured spiro-OMeTAD HTL showing sustained efficiencies even after 840 h of air exposure. PMID:25985417

  17. Improving Performance via Blocking Layers in Dye-Sensitized Solar Cells Based on Nanowire Photoanodes.

    PubMed

    Li, Luping; Xu, Cheng; Zhao, Yang; Chen, Shikai; Ziegler, Kirk J

    2015-06-17

    Electron recombination in dye-sensitized solar cells (DSSCs) results in significant electron loss and performance degradation. However, the reduction of electron recombination via blocking layers in nanowire-based DSSCs has rarely been investigated. In this study, HfO2 or TiO2 blocking layers are deposited on nanowire surfaces via atomic layer deposition (ALD) to reduce electron recombination in nanowire-based DSSCs. The control cell consisting of ITO nanowires coated with a porous shell of TiO2 by TiCl4 treatment yields an efficiency of 2.82%. The efficiency increases dramatically to 5.38% upon the insertion of a 1.3 nm TiO2 compact layer between the nanowire surface and porous TiO2 shell. This efficiency enhancement implies that porous sol-gel coatings on nanowires (e.g., via TiCl4 treatment) result in significant electron recombination in nanowire-based DSSCs, while compact coatings formed by ALD are more advantageous because of their ability to act as a blocking layer. By comparing nanowire-based DSSCs with their nanoparticle-based counterparts, we find that the nanowire-based DSSCs suffer more severe electron recombination from ITO due to the much higher surface area exposed to the electrolyte. While the insertion of a high band gap compact layer of HfO2 between the interface of the conductive nanowire and TiO2 shell improves performance, a comparison of the cell performance between TiO2 and HfO2 compact layers indicates that charge collection is suppressed by the difference in energy states. Consequently, the use of high band gap materials at the interface of conductive nanowires and TiO2 is not recommended. PMID:26010178

  18. Improvement of device performance by using zinc oxide in hybrid organic-inorganic solar cells

    NASA Astrophysics Data System (ADS)

    Hayakawa, Akinobu; Sagawa, Takashi

    2016-02-01

    Zinc oxide (ZnO) nanopowder was applied to hybrid solar cells in combination with poly(3-hexylthiophene). Stability tests of the hybrid solar cell with or without encapsulation with glass and UV cut-off films were performed under 1 sun at 63 °C at a relative humidity of 50%. It was found that the sealed cell showed worse device performance in terms of the loss of the open-circuit voltage (Voc), whereas the unsealed cell exposed to air retained an almost constant Voc for more than 3 d under dark and atmospheric conditions. Placement in O2 atmosphere in the dark led to the recovery of Voc. Cation (Sn4+) doping into ZnO was performed, and the loss of Voc was effectively suppressed through the restraint of the supply of the excited electron from the valence band to the conduction band.

  19. Disorder improves nanophotonic light trapping in thin-film solar cells

    SciTech Connect

    Paetzold, U. W. Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Carius, R.; Rau, U.; Michaelis, D.; Waechter, C.

    2014-03-31

    We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500 nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500 nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures.

  20. Utilizing insulating nanoparticles as the spacer in laminated flexible polymer solar cells for improved mechanical stability.

    PubMed

    Lu, Yunzhang; Alexander, Clement; Xiao, Zhengguo; Yuan, Yongbo; Zhang, Runyu; Huang, Jinsong

    2012-08-31

    Roll-to-roll lamination is one promising technique to produce large-area organic electronic devices such as solar cells with a large through output. One challenge in this process is the frequent electric point shorting of the cathode and anode by the excess or concentrated applied stress from many possible sources. In this paper, we report a method to avoid electric point shorting by incorporating insulating and hard barium titanate (BaTiO(3)) nanoparticles (NPs) into the active layer to work as a spacer. It has been demonstrated that the incorporated BaTiO(3) NPs in poly(3-hexylthiophene):[6,6]-phenyl-c-61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction solar cells cause no deleterious effect to the power conversion process of this type of solar cell. The resulting laminated devices with NPs in the active layer display the same efficiency as the devices without NPs, while the laminated devices with NPs can sustain a ten times higher lamination stress of over 6 MPa. The flexible polymer solar cell device with incorporated NPs shows a much smaller survivable curvature radius of 4 mm, while a regular flexible device can only sustain a bending curvature radius of 8 mm before fracture. PMID:22886059

  1. Improving Light Harvesting in Dye-Sensitized Solar Cells Using Hybrid Bimetallic Nanostructures

    DOE PAGESBeta

    Zarick, Holly F.; Erwin, William R.; Boulesbaa, Abdelaziz; Hurd, Olivia K.; Webb, Joseph A.; Puretzky, Alexander A.; Geohegan, David B.; Bardhan, Rizia

    2016-01-25

    In this paper, we demonstrate improved light trapping in dye-sensitized solar cells (DSSCs) with hybrid bimetallic gold core/silver shell nanostructures. Silica-coated bimetallic nanostructures (Au/Ag/SiO2 NSs) integrated in the active layer of DSSCs resulted in 7.51% power conversion efficiency relative to 5.97% for reference DSSCs, giving rise to 26% enhancement in device performance. DSSC efficiencies were governed by the particle density of Au/Ag/SiO2 NSs with best performing devices utilizing only 0.44 wt % of nanostructures. We performed transient absorption spectroscopy of DSSCs with variable concentrations of Au/Ag/SiO2 NSs and observed an increase in amplitude and decrease in lifetime with increasing particlemore » density relative to reference. Finally, we attributed this trend to plasmon resonant energy transfer and population of the singlet excited states of the sensitizer molecules at the optimum concentration of NSs promoting enhanced exciton generation and rapid charge transfer into TiO2.« less

  2. Laser Induced Forward Transfer for front contact improvement in silicon heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Colina, M.; Morales-Vilches, A.; Voz, C.; Martín, I.; Ortega, P.; Orpella, A.; López, G.; Alcubilla, R.

    2015-05-01

    In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms occurs when a sequence of laser pulses impinging onto the doped layer propels the material toward the substrate. The laser irradiation not only transfers the doping material but also produces a local heating that promotes its diffusion into the substrate. The laser employed was a 1064 nm, lamp-pumped system, working at pulse durations of 100 and 400 ns. In order to obtain a good electrical performance a comprehensive optimization of the applied laser fluency and number of pulses was carried out. Subsequently, arrays of n + p local junctions were created by LIFT and the resulting J-V curves demonstrated the formation of good quality n+ regions. These structures were finally incorporated to enhance the front contact in conventional silicon heterojunction solar cells leading to an improvement of conversion efficiency.

  3. High molecular weight insulating polymers can improve the performance of molecular solar cells

    NASA Astrophysics Data System (ADS)

    Huang, Ye; Wen, Wen; Kramer, Edward; Bazan, Guillermo

    2014-03-01

    Solution-processed molecular semiconductors for the fabrication of solar cells have emerged as a competitive alternative to their conjugated polymer counterparts, primarily because such materials systems exhibit no batch-to-batch variability, can be purified to a greater extent and offer precisely defined chemical structures. Highest power conversion efficiencies (PCEs) have been achieved through a combination of molecular design and the application of processing methods that optimize the bulk heterojunction (BHJ) morphology. However, one finds that the methods used for controlling structural order, for example the use of high boiling point solvent additives, have been inspired by examination of the conjugated polymer literature. It stands to reason that a different class of morphology modifiers should be sought that address challenges unique to molecular films, including difficulties in obtaining thicker films and avoiding the dewetting of active photovoltaic layers. Here we show that the addition of small quantities of high molecular weight polystyrene (PS) is a very simple to use and economically viable additive that improves PCE. Remarkably, the PS spontaneously accumulates away from the electrodes as separate domains that do not interfere with charge extraction and collection or with the arrangement of the donor and acceptor domains in the BHJ blend.

  4. Improved Performance of Electroplated CZTS Thin-Film Solar Cells with Bifacial Configuration.

    PubMed

    Ge, Jie; Yu, Yue; Ke, Weijun; Li, Jian; Tan, Xinxuan; Wang, Zhiwei; Chu, Junhao; Yan, Yanfa

    2016-08-23

    Annealing in S vapor greatly improves the performance of electroplated Cu2 ZnSnS4 (CZTS) solar cells based on the bifacial configuration of Al-doped ZnO (AZO, front contact)/ZnO/CdS/CZTS/indium tin oxide (ITO, back contact), as compared to H2 S annealing in our previous works. S-vapor annealing does not cause severe damage to the conductivity of the ITO back contact. The highest device efficiency of 5.8 % was reached under 1 sun illumination from the AZO side. The well-preformed devices based on the ITO back contact demonstrate smaller series resistances and better fill factors, as compared to our substrate-type devices using Mo back contacts. An interfacial reaction at the ITO back contact has been revealed in experiments, which contributes to the formation of SnO2 -enriched interfacial layer and diffusion of In from ITO into CZTS through the Sn sites. Incorporation of In does not significantly change the optical and structural properties or the grain size of CZTS absorbers. PMID:27400033

  5. Interface Engineering through Atomic Layer Deposition towards Highly Improved Performance of Dye-Sensitized Solar Cells

    PubMed Central

    Lu, Hao; Tian, Wei; Guo, Jun; Li, Liang

    2015-01-01

    A composite photoanode comprising ultralong ZnO nanobelts and TiO2 nanoparticles was prepared and its performance in dye-sensitized solar cells (DSSCs) was optimized and compared to the photoanode consisting of conventional TiO2 nanoparticles. The ultralong ZnO nanobelts were synthesized in high yield by a facile solution approach at 90 oC followed by annealing at 500 oC. The effect of the ratio of ZnO nanobelts to TiO2 nanoparticles on the light scattering, specific surface area, and interface recombination were investigated. An optimum amount of ZnO nanobelts enhanced the photon-conversion efficiency by 61.4% compared to that of the conventional TiO2 nanoparticles. To further reduce the recombination rate and increase the carrier lifetime, Atomic Layer Deposition (ALD) technique was utilized to coat a continuous TiO2 film surrounding the ZnO nanobelts and TiO2 nanoparticles, functioning as a barrier-free access of all electrons to conductive electrodes. This ALD treatment improved the interface contact within the whole photoanode system, finally leading to significant enhancement (137%) in the conversion efficiency of DSSCs. PMID:26238737

  6. 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.

  7. Performance Improvement of Polymer Solar Cells by Surface-Energy-Induced Dual Plasmon Resonance.

    PubMed

    Yao, Mengnan; Shen, Ping; Liu, Yan; Chen, Boyuan; Guo, Wenbin; Ruan, Shengping; Shen, Liang

    2016-03-01

    The surface plasmon resonance (SPR) effect of metal nanoparticles (MNPs) is effectively applied on polymer solar cells (PSCs) to improve power conversion efficiency (PCE). However, universality of the reported results mainly focused on utilizing single type of MNPs to enhance light absorption only in specific narrow wavelength range. Herein, a surface-energy-induced dual MNP plasmon resonance by thermally evaporating method was presented to achieve the absorption enhancement in wider range. The differences of surface energy between silver (Ag), gold (Au), and tungsten trioxide (WO3) compared by contact angle images enable Ag and Au prefer to respectively aggregate into isolated islands rather than films at the initial stage of the evaporation process, which was clearly demonstrated in the atomic force microscopy (AFM) measurement. The sum of plasmon-enhanced wavelength range induced by both Ag NPs (350-450 nm) and Au NPs (450-600 nm) almost cover the whole absorption spectra of active layers, which compatibly contribute a significant efficiency improvement from 4.57 ± 0.16 to 6.55 ± 0.12% compared to the one without MNPs. Besides, steady state photoluminescence (PL) measurements provide strong evidence that the SPR induced by the Ag-Au NPs increase the intensity of light absorption. Finally, ultraviolet photoelectron spectroscopy (UPS) reveals that doping Au and Ag causes upper shift of both the work function and valence band of WO3, which is directly related to hole collection ability. We believe the surface-energy-induced dual plasmon resonance enhancement by simple thermally evaporating technique might pave the way toward higher-efficiency PSCs. PMID:26900763

  8. Fabrication of heterojunction solar cells by improved tin oxide deposition on insulating layer

    DOEpatents

    Feng, Tom; Ghosh, Amal K.

    1980-01-01

    Highly efficient tin oxide-silicon heterojunction solar cells are prepared by heating a silicon substrate, having an insulating layer thereon, to provide a substrate temperature in the range of about 300.degree. C. to about 400.degree. C. and thereafter spraying the so-heated substrate with a solution of tin tetrachloride in a organic ester boiling below about 250.degree. C. Preferably the insulating layer is naturally grown silicon oxide layer.

  9. Improved performance and stability in quantum dot solar cells through band alignment engineering

    NASA Astrophysics Data System (ADS)

    Chuang, Chia-Hao M.; Brown, Patrick R.; Bulović, Vladimir; Bawendi, Moungi G.

    2014-08-01

    Solution processing is a promising route for the realization of low-cost, large-area, flexible and lightweight photovoltaic devices with short energy payback time and high specific power. However, solar cells based on solution-processed organic, inorganic and hybrid materials reported thus far generally suffer from poor air stability, require an inert-atmosphere processing environment or necessitate high-temperature processing, all of which increase manufacturing complexities and costs. Simultaneously fulfilling the goals of high efficiency, low-temperature fabrication conditions and good atmospheric stability remains a major technical challenge, which may be addressed, as we demonstrate here, with the development of room-temperature solution-processed ZnO/PbS quantum dot solar cells. By engineering the band alignment of the quantum dot layers through the use of different ligand treatments, a certified efficiency of 8.55% has been reached. Furthermore, the performance of unencapsulated devices remains unchanged for over 150 days of storage in air. This material system introduces a new approach towards the goal of high-performance air-stable solar cells compatible with simple solution processes and deposition on flexible substrates.

  10. Improved performance and stability in quantum dot solar cells through band alignment engineering.

    PubMed

    Chuang, Chia-Hao M; Brown, Patrick R; Bulović, Vladimir; Bawendi, Moungi G

    2014-08-01

    Solution processing is a promising route for the realization of low-cost, large-area, flexible and lightweight photovoltaic devices with short energy payback time and high specific power. However, solar cells based on solution-processed organic, inorganic and hybrid materials reported thus far generally suffer from poor air stability, require an inert-atmosphere processing environment or necessitate high-temperature processing, all of which increase manufacturing complexities and costs. Simultaneously fulfilling the goals of high efficiency, low-temperature fabrication conditions and good atmospheric stability remains a major technical challenge, which may be addressed, as we demonstrate here, with the development of room-temperature solution-processed ZnO/PbS quantum dot solar cells. By engineering the band alignment of the quantum dot layers through the use of different ligand treatments, a certified efficiency of 8.55% has been reached. Furthermore, the performance of unencapsulated devices remains unchanged for over 150 days of storage in air. This material system introduces a new approach towards the goal of high-performance air-stable solar cells compatible with simple solution processes and deposition on flexible substrates. PMID:24859641

  11. Investigation of the magnetic nickel nanoparticle on performance improvement of P3HT:PCBM solar cell

    NASA Astrophysics Data System (ADS)

    Gong, Xiu; Jiang, Yurong; Zhang, Congcong; Yang, Lei; Li, Meng; Ma, Heng

    2016-04-01

    This work reports an investigation on the performance improvement of bulk heterojunction polymer solar cells made of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) blend system by introducing nickel nanoparticles (Ni NPs). Using the simplest cell structure, the addition ratio of 2 % of Ni NPs results in a remarkable increase in the light absorption and the short current, which brings an enhancement on power conversion efficiency with 25 % compared with the reference device. The analysis indicates that the electromagnetic surface wave generated from Ni NPs coupled with the photoactive layer forms surface plasmon resonance, which can result in a light trapping effect to increase the light absorption. As a conclusion, the inexpensive Ni NPs may provide an effect and alternative process on the performance improvement of the polymer solar devices.

  12. Improvement in the performance of inverted organic solar cell using electric field assisted spray deposited ZnO layer

    NASA Astrophysics Data System (ADS)

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2015-06-01

    ZnO film was deposited using spray technique. The application of electric field (applying a DC voltage = 700V to the nozzle) during spray deposition provide compact nanostructured film of ZnO as compared to agglomerated ZnO film deposited using spray process. The ZnO film deposited after applying DC voltage during spray process showed good crystallinity as well as transmittance in the visible range. Use of this crystalline, compact layer of ZnO in inverted organic solar cell (ITO/ZnO/P3HT: PCBM/Ag) provide improved efficiency of 2.8% with JSC of 14.0 mA/cm2, VOC of 0.55V and FF of 36%. Thus the process remove the need of any post deposition treatment to improve the film quality as well as solar cell performance.

  13. Improvement in open circuit voltage of MEHPPV-FeS2 nanoparticle based organic inorganic hybrid solar cell

    NASA Astrophysics Data System (ADS)

    Layek, Animesh; Middya, Somnath; Ray, Partha Pratim

    2013-02-01

    In this study we have synthesized high quality FeS2 nanoparticles by solvothermal route and was applied as semiconducting acceptor in MEHPPV:FeS2 nanoparticle based organic inorganic hybrid solar cells. The open circuit voltage improved from 0.64V to 0.72V of the device due to modification of band gap of donor material by introducing nanoparticles.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  15. 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

  16. Improved Energy Conversion Efficiency in Wide-Bandgap Cu(In,Ga)Se2 Solar Cells: Preprint

    SciTech Connect

    Contreras, M.; Mansfield, L.; Egaas, B.; Li, J.; Romero, M.; Noufi, R.; Rudiger-Voigt, E.; Mannstadt, W.

    2011-07-01

    This report outlines improvements to the energy conversion efficiency in wide bandgap (Eg>1.2 eV) solar cells based on CuIn1-xGaxSe2. Using (a) alkaline containing high temperature glass substrates, (b) elevated substrate temperatures 600˚C-650˚C and (c) high vacuum evaporation from elemental sources following NREL's three-stage process, we have been able to improve the performance of wider bandgap solar cells with 1.218% for absorber bandgaps ~1.30 eV and efficiencies ~16% for bandgaps up to ~1.45 eV. In comparing J-V parameters in similar materials, we establish gains in the open-circuit voltage and, to a lesser degree, the fill factor value, as the reason for the improved performance. The higher voltages seen in these wide gap materials grown at high substrate temperatures may be due to reduced recombination at the grain boundary of such absorber films. Solar cell results, absorber materials characterization, and experimental details are reported.

  17. Performance improvement of CdS/Cu(In,Ga)Se2 solar cells after rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Chen, Dong-Sheng; Yang, Jie; Xu, Fei; Zhou, Ping-Hua; Du, Hui-Wei; Shi, Jian-Wei; Yu, Zheng-Shan; Zhang, Yu-Hong; Brian, Bartholomeusz; Ma, Zhong-Quan

    2013-01-01

    In this paper, we investigated the effect of rapid thermal annealing (RTA) on solar cell performance. An opto-electric conversion efficiency of 11.75% (Voc = 0.64 V, Jsc = 25.88 mA/cm2, FF=72.08%) was obtained under AM 1.5G when the cell was annealed at 300 °C for 30 s. The annealed solar cell showed an average absolute efficiency 1.5% higher than that of the as-deposited one. For the microstructure analysis and the physical phase confirmation, X-ray diffraction (XRD), Raman spectra, front surface reflection (FSR), internal quantum efficiency (IQE), and X-ray photoelectron spectroscopy (XPS) were respectively applied to distinguish the causes inducing the efficiency variation. All experimental results implied that the RTA eliminated recombination centers at the p-n junction, reduced the surface optical losses, enhanced the blue response of the CdS buffer layer, and improved the ohmic contact between Mo and Cu(In, Ga)Se2 (CIGS) layers. This leaded to the improved performance of CIGS solar cell.

  18. 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.

  19. Carbon nanotube-amorphous silicon hybrid solar cell with improved conversion efficiency.

    PubMed

    Funde, Adinath M; Nasibulin, Albert G; Syed, Hashmi Gufran; Anisimov, Anton S; Tsapenko, Alexey; Lund, Peter; Santos, J D; Torres, I; Gandía, J J; Cárabe, J; Rozenberg, A D; Levitsky, Igor A

    2016-05-01

    We report a hybrid solar cell based on single walled carbon nanotubes (SWNTs) interfaced with amorphous silicon (a-Si). The high quality carbon nanotube network was dry transferred onto intrinsic a-Si forming Schottky junction for metallic SWNT bundles and heterojunctions for semiconducting SWNT bundles. The nanotube chemical doping and a-Si surface treatment minimized the hysteresis effect in current-voltage characteristics allowing an increase in the conversion efficiency to 1.5% under an air mass 1.5 solar spectrum simulator. We demonstrated that the thin SWNT film is able to replace a simultaneously p-doped a-Si layer and transparent conductive electrode in conventional amorphous silicon thin film photovoltaics. PMID:27005494

  20. Carbon nanotube-amorphous silicon hybrid solar cell with improved conversion efficiency

    NASA Astrophysics Data System (ADS)

    Funde, Adinath M.; Nasibulin, Albert G.; Gufran Syed, Hashmi; Anisimov, Anton S.; Tsapenko, Alexey; Lund, Peter; Santos, J. D.; Torres, I.; Gandía, J. J.; Cárabe, J.; Rozenberg, A. D.; Levitsky, Igor A.

    2016-05-01

    We report a hybrid solar cell based on single walled carbon nanotubes (SWNTs) interfaced with amorphous silicon (a-Si). The high quality carbon nanotube network was dry transferred onto intrinsic a-Si forming Schottky junction for metallic SWNT bundles and heterojunctions for semiconducting SWNT bundles. The nanotube chemical doping and a-Si surface treatment minimized the hysteresis effect in current-voltage characteristics allowing an increase in the conversion efficiency to 1.5% under an air mass 1.5 solar spectrum simulator. We demonstrated that the thin SWNT film is able to replace a simultaneously p-doped a-Si layer and transparent conductive electrode in conventional amorphous silicon thin film photovoltaics.

  1. 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…

  2. Indium-tin oxide films obtained by DC magnetron sputtering for improved Si heterojunction solar cell applications

    NASA Astrophysics Data System (ADS)

    Gu, Jin-Hua; Si, Jia-Le; Wang, Jiu-Xiu; Feng, Ya-Yang; Gao, Xiao-Yong; Lu, Jing-Xiao

    2015-11-01

    The indium-tin oxide (ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction (HJ) solar cells. To obtain high transmittance and low resistivity ITO films by direct-current (DC) magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4×10-4 Ω·m and average transmittance of 89% in the wavelength range of 380-780 nm were obtained under the optimized conditions: oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si:H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage (Voc) of 0.626 V, a filling factor (FF) of 0.50, and a short circuit current density (Jsc) of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si:H layer was inserted between the (p) a-Si:H and (n) c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si:H. Project supported by the National High Technology Research and Development Program of China (Grant No. 2011AA050501).

  3. Improved solar heating systems

    DOEpatents

    Schreyer, J.M.; Dorsey, G.F.

    1980-05-16

    An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

  4. Comprehensive Insights into Charge Dynamics and Improved Photoelectric Properties of Well-Designed Solar Cells.

    PubMed

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong

    2016-08-17

    Here, Zn2SnO4 nanorods/Cu4Bi4S9 (ZTO/CBS) and ZTO nanorods/CBS-graphene nanosheets (ZTO/CBS-GNs), as well as two types of bulk heterojunction (BHJ) solar cells with high flexibility were fabricated on stainless steel meshes (SSMs). The excellent photovoltaic responses of CBS-GNs and ZTO/CBS-GNs with incorporation of GNs were determined using surface photovoltage spectroscopy (SPS). The signals of time-resolved fluorescence response (TFR) and transient surface photovoltage (TPV) can provide more detailed information for transition, separation, and transport of photoinduced carriers. Besides, the ZTO nanorods/CBS-GNs cell exhibits the superior performance and the highest efficiency is 11.2%. The multichannel separation process from the TPVs indicates that the macro-photoelectric signals can be attributed to the photogenerated charges separated at the interface of CBS/GNs, rather than CBS/ZTO. The multi-interfacial recombination is the major carrier loss with electrical impedance spectroscopy (EIS) and the hole selective NiO can efficiently accelerate the charge extraction to the external circuit. The comprehensive signals of SPS, EIS, TFR, and TPV provide insights into transition, separation, recombination and shifting of carriers. Importantly, the BHJ flexible solar cells with high efficiency and facile, scalable production present a potential for application. PMID:27455131

  5. Improving Performance of Dye-Sensitized Solar Cell by Multi-Emission Effect of Phosphors.

    PubMed

    Kim, Young Moon; Kim, Chang Seob; Choi, Hyung Wook

    2015-10-01

    Generally, the N-719 dye, used in dye-sensitized solar cells (DSSCs), only absorbs visible light in the wavelength range from 400 to 700 nm. Consequently, most of the ultraviolet and infrared rays from the sun are not utilized by this dye. However, ultraviolet and infrared rays can be converted to visible light by upconversion luminescence. Such visible light can then be reabsorbed by the dye, allowing for a larger range of solar irradiation to be utilized in DSSCs. Phosphor (ZnGa2O4, Y2O3:Er(3+)), acting as a luminescence medium, was added to the TiO2 electrode of DSSCs, and owing to the effect of upconversion, it increased their photocurrent density and efficiency. Phosphor (ZnGa2O4, Y2O3:Er(3+)) co-doped TiO2 electrode cells showed better performance than phosphor-free cells. In fact, the highest efficiency observed for a DSSC containing five phosphor layers was 7.03% with a short-circuit current density (Jsc) of 15.62 mA/cm2, an open circuit voltage (Voc) of 0.661 V, and a fill factor (FF) of 68.17%. PMID:26726482

  6. Post-black etching on emitter to improve performance of multi-scale texture silicon solar cells

    NASA Astrophysics Data System (ADS)

    Jiang, Yurong; Yang, Haigang; Cao, Weiwei; Wang, Guangna; Ma, Heng; Chang, Fanggao

    2014-09-01

    A simple, low-cost, post-black etching process atop the random pyramidal emitter has been proposed and investigated. The multi-scale texture is achieved by combining nanoporous layer formed by the post-black etching with micron-scale pyramid texture. Compared to the pre-black etched Si solar cells, our experiments clearly show the advantage of post-black etched texturing: it enables high blue response and improved conversion efficiency. As a result, the enhancement of 7.1 mA/cm2 on the short-circuit current density and improvement of 31 % in the conversion efficiency have been reached.

  7. Study program to improve the open-circuit voltage of low resistivity single crystal silicon solar cells

    NASA Technical Reports Server (NTRS)

    Minnucci, J. A.; Matthei, K. W.

    1980-01-01

    The results of a 14 month program to improve the open circuit voltage of low resistivity silicon solar cells are described. The approach was based on ion implantation in 0.1- to 10.0-ohm-cm float-zone silicon. As a result of the contract effort, open circuit voltages as high as 645 mV (AMO 25 C) were attained by high dose phosphorus implantation followed by furnace annealing and simultaneous SiO2 growth. One key element was to investigate the effects of bandgap narrowing caused by high doping concentrations in the junction layer. Considerable effort was applied to optimization of implant parameters, selection of furnace annealing techniques, and utilization of pulsed electron beam annealing to minimize thermal process-induced defects in the completed solar cells.

  8. Improving scattering layer through mixture of nanoporous spheres and nanoparticles in ZnO-based dye-sensitized solar cells

    PubMed Central

    2014-01-01

    A scattering layer is utilized by mixing nanoporous spheres and nanoparticles in ZnO-based dye-sensitized solar cells. Hundred-nanometer-sized ZnO spheres consisting of approximately 35-nm-sized nanoparticles provide not only effective light scattering but also a large surface area. Furthermore, ZnO nanoparticles are added to the scattering layer to facilitate charge transport and increase the surface area as filling up large voids. The mixed scattering layer of nanoparticles and nanoporous spheres on top of the nanoparticle-based electrode (bilayer geometry) improves solar cell efficiency by enhancing both the short-circuit current (Jsc) and fill factor (FF), compared to the layer consisting of only nanoparticles or nanoporous spheres. PMID:24982606

  9. Improvement of power efficiency of polymer solar cell based on P3HT: PCBM blends

    NASA Astrophysics Data System (ADS)

    Li, Weimin; Guo, Jinchuan; Sun, Xiuquan; Zhou, Bin

    2008-03-01

    The effect of interlayer on the performance of a poly[2-methoxy-5-(3',7'-dimethylocty)-1,4-phenylenevinylene] (MDMO-PPV)/1-(3-methoxycarbony 1)-propy1-1 phney1-(6-6)C 61 (PCBM) composite solar cell device has been reported recently. Herein we report bulk heterojunction organic solar cell with efficiency enhanced by interlayer made from blend film of regioregular poly(3-hexylthiophene)(P3HT) and PCBM. The interlayer, poly(9,9-dioctylfluorene)-co-N-(1,4-butylphenyl)diphenylamine)(TFB), was inserted between the poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic acid)(PEDOT:PPS) and the active layer. With the interlayer, the efficiency was enhanced due to the increased short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) obtained from testing and calculation. According to the analysis, the interlayer TFB, acting as an effective exciton-blocking layer, prevented the severe quenching of radiative excitons between the interface of PEDOT:PSS. In the study, the interlayer increased Jsc from 0.891 mA/cm2 to 1.025 mA/cm -2, Voc from 0.478 V to 0.526 V, and FF from 0.327 to 0.416, under illumination by white light from a solar simulator with an incident intensity of 80mW/cm2; the power conversion efficiency of the device reached higher value 0.280% comparing with 0.174% with no interlayer.

  10. Material growth and characterization directed toward improving III-V heterojunction solar cells

    NASA Technical Reports Server (NTRS)

    Stefanakos, E. K.; Alexander, W. E.; Collis, W.; Abul-Fadl, A.

    1979-01-01

    In addition to the existing materials growth laboratory, the photolithographic facility and the device testing facility were completed. The majority of equipment for data acquisition, solar cell testing, materials growth and device characterization were received and are being put into operation. In the research part of the program, GaAs and GaA1As layers were grown reproducibly on GaAs substrates. These grown layers were characterized as to surface morphology, thickness and thickness uniformity. The liquid phase epitaxial growth process was used to fabricate p-n junctions in Ga(1-x)A1(x)As. Sequential deposition of two alloy layers was accomplished and detailed analysis of the effect of substrate quality and dopant on the GaA1As layer quality is presented. Finally, solar cell structures were formed by growing a thin p-GaA1As layer upon an epitaxial n-GaA1As layer. The energy gap corresponding to the long wavelength cutoff of the spectral response characteristic was 1.51-1.63 eV. Theoretical calculations of the spectral response were matched to the measured response.

  11. Improvement in light harvesting in a dye sensitized solar cell based on cascade charge transfer.

    PubMed

    Yang, Lijun; Leung, Wallace Woon-Fong; Wang, Jingchuan

    2013-08-21

    Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future. PMID:23831867

  12. Toward Better Understanding and Improved Performance of Silicon Heterojunction Solar Cells: Preprint

    SciTech Connect

    Wang, T. H.; Page, M. R.; Iwaniczko, E.; Levi, D. H.; Yan, Y.; Branz, H. M.; Yelundur, V.; Rohatgi, A.; Bunea, G.; Terao, A.; Wang, Q.

    2004-08-01

    The double-sided silicon heterojunction (SHJ) solar cell is more appropriate for n-type crystal silicon (c-Si) wafers than for p-type c-Si wafers because there is a larger band offset to the valence band edge of hydrogenated amorphous silicon than to the conduction band edge. Thin intrinsic and doped hydrogenated amorphous silicon (a Si:H) double layers by hot-wire chemical vapor deposition (HWCVD) are investigated as passivation layers, emitters, and back-surface-field (BSF) contacts to both p- and n-type wafers. Passivation quality is studied by characterizing the SHJ solar cells and by photoconductive decay (PCD) minority-carrier lifetime measurements. The crystal-amorphous heterointerface is studied with real-time spectroscopic ellipsometry (RTSE) and high-resolution transmission electron microscopy (HRTEM) to detect phase change and material evolution, with a focus on better understanding the factors determining passivation effectiveness. A common feature in effective passivation, emitter, and BSF layers is immediate a-Si:H deposition and an abrupt and flat interface to the c-Si substrate. In this case, good wafer passivation or an excellent heterojunction is obtained, with a low interface recombination velocity (S) or a high open-circuit voltage (Voc). Voc greater than 640 mV, S less than 15 cm/sec, and efficiency of 14.8% have been achieved on polished p type Czochralski-grown (CZ) Si wafers. Collaboration between NREL and Georgia Tech resulted in a 15.7%-efficient HWCVD-deposited SHJ cell on non-textured FZ-Si with a screen-printed Al back surface field (BSF), the highest reported HWCVD SHJ cell. Collaboration between NREL and SunPower demonstrated that HWCVD a-Si:H passivation can be better than the conventional oxides, with a low surface recombination velocity of 42 cm/sec on textured n-type FZ-Si.

  13. Nanowire Solar Cells

    NASA Astrophysics Data System (ADS)

    Garnett, Erik C.; Brongersma, Mark L.; Cui, Yi; McGehee, Michael D.

    2011-08-01

    The nanowire geometry provides potential advantages over planar wafer-based or thin-film solar cells in every step of the photoconversion process. These advantages include reduced reflection, extreme light trapping, improved band gap tuning, facile strain relaxation, and increased defect tolerance. These benefits are not expected to increase the maximum efficiency above standard limits; instead, they reduce the quantity and quality of material necessary to approach those limits, allowing for substantial cost reductions. Additionally, nanowires provide opportunities to fabricate complex single-crystalline semiconductor devices directly on low-cost substrates and electrodes such as aluminum foil, stainless steel, and conductive glass, addressing another major cost in current photovoltaic technology. This review describes nanowire solar cell synthesis and fabrication, important characterization techniques unique to nanowire systems, and advantages of the nanowire geometry.

  14. Catalytic Improvement on Counter Electrode of Dye-Sensitized Solar Cells Using Electrospun Pt Nano-Fibers.

    PubMed

    Seol, Hyunwoong; Shiratani, Masaharu; Seneekatima, Kannanut; Pornprasertsuk, Rojana

    2016-04-01

    A dye-sensitized solar cell is one of cost-competitive photovoltaic devices. For higher performance, all components have been actively studied and improved. However, Pt is still a dominant catalyst since first development although some catalytic materials were studied so far. Catalytic materials of counter electrode play an important role in the performance because it supplies electrons from counter electrode to electrolyte. Therefore, the catalytic activation of counter electrode is closely connected with the performance enhancement. In this work, Pt nano-fiber was fabricated by electrospinning and applied for the counter electrode. Its wide surface area is advantageous for good conductivity and catalytic activation. Morphological characteristics of nano-fibers were analyzed according to electrospinning conditions. Photovoltaic properties, cyclic voltammetry, impedance analysis verified the catalytic activation. Consequently, dye-sensitized solar cell with Pt nano-fiber electrospun at 5.0 kV of applied voltage had higher performance than conventional dye-sensitized solar cell with Pt thin film. This work is significant for related researches because all nano-fibers counter electrode material proposed so far never exceeded the performance of conventional Pt counter electrode. PMID:27451627

  15. New strategies in laser processing of TCOs for light management improvement in thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Lauzurica, S.; Lluscà, M.; Canteli, D.; Sánchez-Aniorte, M. I.; López-Vidrier, J.; Hernández, S.; Bertomeu, J.; Molpeceres, C.

    2014-10-01

    Light confinement strategies play a crucial role in the performance of thin-film (TF) silicon solar cells. One way to reduce the optical losses is the texturing of the transparent conductive oxide (TCO) that acts as the front contact. Other losses arise from the mismatch between the incident light spectrum and the spectral properties of the absorbent material that imply that low energy photons (below the bandgap value) are not absorbed, and therefore can not generate photocurrent. Up-conversion techniques, in which two sub-bandgap photons are combined to give one photon with a better matching with the bandgap, were proposed to overcome this problem. In particular, this work studies two strategies to improve light management in thin film silicon solar cells using laser technology. The first one addresses the problem of TCO surface texturing using fully commercial fast and ultrafast solid state laser sources. Aluminum doped Zinc Oxide (AZO) samples were laser processed and the results were optically evaluated by measuring the haze factor of the treated samples. As a second strategy, laser annealing experiments of TCOs doped with rare earth ions are presented as a potential process to produce layers with up-conversion properties, opening the possibility of its potential use in high efficiency solar cells.

  16. 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%).

  17. Bilayer Polymer Solar Cells with Improved Power Conversion Efficiency and Enhanced Spectrum Coverage

    SciTech Connect

    Kekuda, Dhananjaya; Chu, Chih-Wei

    2011-10-20

    We demonstrate the construction of an efficient bilayer polymer solar cell comprising of Poly(3-hexylthiophene)(P3HT) as a p-type semiconductor and asymmetric fullerene (C{sub 70}) as n-type counterparts. The bilayer configuration was very efficient compared to the individual layer performance and it behaved like a regular p-n junction device. The photovoltaic characteristic of the bilayers were studied under AM 1.5 solar radiation and the optimized device parameters are the following: Voc = 0.5V, Jsc = 10.1 mA/cm{sup 2}, FF = 0.60 and power conversion efficiency of 3.6 %. A high fill factor of {approx}0.6 was achieved, which is only slightly reduced at very intense illumination. Balanced mobility between p-and n-layers is achieved which is essential for achieving high device performance. Correlation between the crystallinity, morphology and the transport properties of the active layers is established. The External quantum efficiency (EQE) spectral distribution of the bilayer devices with different processing solvents correlates well with the trends of short circuit current densities (J{sub sc}) measured under illumination. Efficiency of the bilayer devices with rough P3HT layer was found to be about 3 times higher than those with a planar P3HT surface. Hence it is desirable to have a larger grains with a rough surface of P3HT layer for providing larger interfacial area for the exciton dissociation.

  18. Boron Doped Nanocrystalline Film with Improved Work Function as a Buffer Layer in Thin Film Silicon Solar Cells.

    PubMed

    Park, Jinjoo; Shin, Chonghoon; Park, Hyeongsik; Jung, Junhee; Lee, Youn-Jung; Bong, Sungjae; Dao, Vinh Ai; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    We investigated thin film silicon solar cells with boron doped hydrogenated nanocrystalline silicon/ hydrogenated amorphous silicon oxide [p-type nc-Si:H/a-SiOx:H] layer. First, we researched the bandgap engineering of diborane (B2H6) doped wide bandgap hydrogenated nanocryslline silicon (p-type nc-Si:H) films, which have excellent electrical properties of high dark conductivity, and low activation energy. The films prepared with lower doping ratio and higher hydrogen dilution ratio had higher optical gap (Eg), with higher dark conductivity (σ(d)), and lower activation energy (Ea). We controlled Eg from 2.10 eV to 1.75 eV, with σ(d) from 1.1 S/cm to 7.59 x 10(-3) S/cm, and Ea from 0.040 eV to 0.128 eV. Next, we focused on the fabrication of thin film silicon solar cells. By inserting p-type nc-Si:H film into the thin film silicon solar cells, we achieved a remarkable increase in the built-in potential from 0.803 eV to 0.901 eV. By forming p-type nc-Si:H film between SnO2:F/ZnO:Al (30 nm) and p-type a-SiOx:H layer, the solar cell properties of open circuit voltage (Voc), short circuit current density (Jsc), and efficiency (η) were improved by 3.7%, 9.2%, and 9.8%, respectively. PMID:26413646

  19. 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.

  20. Improved efficiency of electrodeposited p-CuO/n-Cu2O heterojunction solar cell

    NASA Astrophysics Data System (ADS)

    Jayathilaka, Charith; Kapaklis, Vassilios; Siripala, Withana; Jayanetti, Sumedha

    2015-06-01

    We report electrodeposition of n-type cuprous oxide (Cu2O) films on p-type CuO films electrodeposited on Ti substrates for forming p-CuO/n-Cu2O heterostructures. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed that the films had good structural quality, with substrates being well-covered by the films. The p-CuO/n-Cu2O heterojunctions exhibited good photovoltaic properties and diode characteristics. The surfaces of Cu2O films subject to ammonium sulfide treatment exhibited enhanced photocurrents. Under AM 1.5 illumniation, the obtained sulfur-treated and annealed Ti/p-CuO/n-Cu2O/Au solar cell structure yielded energy conversion efficiency of 0.64%, with Voc = 220 mV and Jsc = 6.8 mA cm-2.

  1. Thylakoid direct photobioelectrocatalysis: utilizing stroma thylakoids to improve bio-solar cell performance.

    PubMed

    Rasmussen, Michelle; Minteer, Shelley D

    2014-08-28

    Thylakoid membranes from spinach were separated into grana and stroma thylakoid fractions which were characterized by several methods (pigment content, protein gel electrophoresis, photosystem activities, and electron microscopy analysis) to confirm that the intact thylakoids were differentiated into the two domains. The results of photoelectrochemical experiments showed that stroma thylakoid electrodes generate photocurrents more than four times larger than grana thylakoids (51 ± 4 nA cm(-2) compared to 11 ± 1 nA cm(-2)). A similar trend was seen in a bio-solar cell configuration with stroma thylakoids giving almost twice the current (19 ± 3 μA cm(-2)) as grana thylakoids (11 ± 2 μA cm(-2)) with no change in open circuit voltage. PMID:25019197

  2. Improved performance of carbon nanotubes—manganese doped cadmium sulfide quantum dot nanocomposite based solar cell

    NASA Astrophysics Data System (ADS)

    Kaur, Rajnish; Priya, Nidhi; Deep, Akash

    2016-01-01

    The nanocomposites of carbon nanotubes with quantum dots (MWCNT-QDS) display the capability of light induced charge dissociation and transport, which make them suitable for photovoltaic applications. The present work reports the coupling of multiwalled CNT (MWCNT) with L-cysteine (2-amino 3-mercaptopropionic acid) capped manganese doped cadmium sulfide QDs (CdS:Mn). The confirmation of the MWCNT-CdS:Mn nanocomposite formation is done with various instrumental techniques. Current-voltage studies of the MWCNT-CdS:Mn thin film indicate their semiconducting behavior. Further, cyclic voltammetry and frequency response analyses of the above MWCNT-CdS:Mn thin film have highlighted their potential application as a photoanode material in dye sanitized solar cells. It has been demonstrated that the use of MWCNT-CdS:Mn nanocomposite as a photoanode material offer better photocurrent characteristics as compared to QDS alone.

  3. Improvements in contact resistivity and thermal stability of Au-contacted InP solar cells

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1991-01-01

    Specific contact resistivities for as-fabricated Au contacts on n-p InP solar cells are typically in the 10(exp -3) ohm/sq cm range, but contact resistivities in the 10(exp -6) ohm/sq cm range can be obtained if the cells are heat treated at 400 C for a few minutes. This heat treatment, however, results in a dramatic drop in the open circuit voltage of the cell due to excessive dissolution of the emitter into the metallization. It was found that low values of contact resistivity can be secured without the accompanying drop in the open circuit voltage by adding Ga and In in the Au metallization. It is shown that Au contacts containing as little as 1 percent atomic Ga can suppress the reaction that takes place at the metal-InP interface during heat treatment, while exhibiting contact resistivity values in the low 10(exp -5) ohm/sq cm. Detailed explanations for the observed superior thermal stability of these contacts are presented.

  4. Dysprosium, holmium and erbium ions doped indium oxide nanotubes as photoanodes for dye sensitized solar cells and improved device performance.

    PubMed

    Miao, Chuang; Chen, Cong; Dai, Qilin; Xu, Lin; Song, Hongwei

    2015-02-15

    In this work, rare earth (RE) ion RE(3+) (RE(3+)=Dy(3+), Ho(3+) and Er(3+)) doped and undoped In2O3 nanotubes are synthesized by the electrospinning method and the band gap of In2O3 is systemically controlled, depending on the order of doped elements. Dye-sensitized solar cells (DSSCs) based on In2O3:RE(3+) nanotubes are also fabricated, and significantly improved performance of In2O3-DSSC is observed due to the modulation of the band gap, larger recombination charge transfer resistance and longer electron lifetime. PMID:25460702

  5. Highly Asymmetric n(+) -p Heterojunction Quantum-Dot Solar Cells with Significantly Improved Charge-Collection Efficiencies.

    PubMed

    Choi, Min-Jae; Kim, Sunchuel; Lim, Hunhee; Choi, Jaesuk; Sim, Dong Min; Yim, Soonmin; Ahn, Byung Tae; Kim, Jin Young; Jung, Yeon Sik

    2016-03-01

    The depletion region width of metal-oxide/quantum-dot (QD) heterojunction solar cells is increased by a new method in which heavily boron-doped n(+) -ZnO is employed. It is effectively increased in the QD layer by 30% compared to the counterpart with conventional n-ZnO, and provides 41% and 37% improvement of Jsc (16.7 mA cm(-2) to 23.5 mA cm(-2) ) and power conversion efficiency (5.52% to 7.55%), respectively. PMID:26689133

  6. Solar cell device

    SciTech Connect

    Nishiura, M.; Haruki, H.; Miyagi, M.; Sakai, H.; Uchida, Y.

    1984-06-26

    A solar cell array is equipped with serially or parallel connected reverse polarity diodes formed simultaneously with the array. The diodes are constituted by one or more solar cells of the array which may be shaded to prevent photoelectric conversion, and which are electrically connected in reverse polarity with respect to the remaining cells.

  7. 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.

  8. 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.

  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. Interfacial quality improvement of Cu(In,Ga)Se2 thin film solar cells by Cu-depletion layer formation

    NASA Astrophysics Data System (ADS)

    Nishimura, Takahito; Toki, Soma; Sugiura, Hiroki; Nakada, Kazuyoshi; Yamada, Akira

    2016-09-01

    Se irradiation with time, t Se, was introduced after the second stage of a three-stage process to control the Cu2Se layer during Cu(In,Ga)Se2 (CIGS) deposition. Open circuit voltage and fill factor of CIGS solar cells could be improved by introducing Se irradiation. We concluded that the control of the Cu2Se layer led to the formation of a Cu-depletion CIGS layer (CDL), which improved conversion efficiency owing to suppression of interfacial recombination by a valence band offset formed between CIGS and the CDL. Finally, highest efficiency of 19.8% was achieved with t Se of 5 min. This very simple and new technique is promising for the improvement of photovoltaic performance.

  11. Improved amorphous Si solar cells. Quarterly progress report No. 5, February 1-April 30, 1981

    SciTech Connect

    Dalal, V.

    1981-11-01

    Both n and p-type a-Si:H films with very high conductivities have been grown by diluting SiH/sub 4/ in Ar or H/sub 2/. These films have Fermi levels close to the conduction and valence bands (0.03 eV). The use of these heavily doped films as p/sup +/ and n/sup +/ junction layers in a p/sup +/in/sup +/ cell should increase the diffusion voltage of the diode, thereby increasing both J/sub sc/ and V/sub oc/. The analysis of conductivity and thermoelectric power on films of diverse thickness have revealed no systematic changes. However, the drift mobility shows a systematic increase with thickness. The analysis of cells by studying quantum efficiency vs. applied voltage has revealed the electron (..mu.. tau) product is limiting transport in nip cells and not the hole (..mu.. tau) product. Analysis reveals that typically (..mu.. tau)/sub eta/ = 10/sup -9/ cm/sup 2//V. A new device design, Tandem parallel-connected cells, has been evolved to improve the current collection in a-Si cells. This design may help increase J/sub sc/ to 15 to 16 mA/cm/sup 2/ in a-Si:H.

  12. Lanthanum Hexaboride As Novel Interlayer for Improving the Thermal Stability of P3HT:PCBM Organic Solar Cells.

    PubMed

    Chambon, Sylvain; Murat, Yolande; Wantz, Guillaume; Hirsch, Lionel; Tardy, Pascal

    2015-11-18

    For efficient organic photovoltaic (OPV) solar cells, a low work function electrode is necessary to enhance the built-in voltage of the active layer, thereby improving the overall efficiency. Calcium is often used for this purpose in the laboratory; however, its development on a larger scale is impaired by its high reactivity with oxygen and water and the resulting low stability of solar cells under operation. The influence of a novel interlayer, lanthanum hexaboride (LaB6), on the electronic properties of OPV is studied in this work. Similarly to calcium, when LaB6 is used as an interlayer, it enhances the built-in voltage in the device, leading to a higher fill factor (FF) and optimal open circuit voltage (V(oc)). As a result, optimized LaB6-based devices present significantly improved power conversion efficiencies. More importantly, while calcium/aluminum (Ca/Al) and aluminum (Al) cathodes lose their capacity to enhance the internal electrical field during thermal aging, the LaB6/aluminum (LaB6/Al) electrode remains stable. This remarkable effect results in a highly stable V(oc) and flat-band potential during aging. PMID:26540482

  13. Improvement of performance of InAs quantum dot solar cell by inserting thin AlAs layers

    PubMed Central

    2011-01-01

    A new measure to enhance the performance of InAs quantum dot solar cell is proposed and measured. One monolayer AlAs is deposited on top of InAs quantum dots (QDs) in multistack solar cells. The devices were fabricated by molecular beam epitaxy. In situ annealing was intended to tune the QD density. A set of four samples were compared: InAs QDs without in situ annealing with and without AlAs cap layer and InAs QDs in situ annealed with and without AlAs cap layer. Atomic force microscopy measurements show that when in situ annealing of QDs without AlAs capping layers is investigated, holes and dashes are present on the device surface, while capping with one monolayer AlAs improves the device surface. On unannealed samples, capping the QDs with one monolayer of AlAs improves the spectral response, the open-circuit voltage and the fill factor. On annealed samples, capping has little effect on the spectral response but reduces the short-circuit current, while increasing the open-circuit voltage, the fill factor and power conversion efficiency. PMID:21711628

  14. 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.

  15. Improved Performance in CuInSe2 and Surface-Modified CuGaSe2 Solar Cells

    SciTech Connect

    AbuShama, J.; Noufi, R.; Johnston, S.

    2005-01-01

    In this paper, we present an update and review on the progress made in the development of low-bandgap CuInSe2 (CIS) and wide-bandgap CuGaSe2 (CGS) solar cells. Our research project is primarily concerned with the optimization of the bottom and top cells of the tandem solar cell. This past year, we achieved new world record total-area efficiencies of 15.0% and 10.2% for CIS and surface-modified CGS solar cells, respectively. These achievements were possible by modifying the growth process for CIS and CGS absorbers. We attempt to modify the surface region of the CGS absorber to be CIGS-like in composition. In the mean time, we are designing a mechanical-stacked tandem solar cell where the CIS cell serves as the bottom cell.

  16. Polycrystalline Silicon Sheets for Solar Cells by the Improved Spinning Method

    NASA Technical Reports Server (NTRS)

    Maeda, Y.; Yokoyama, T.; Hide, I.

    1984-01-01

    Cost reduction of silicon materials in the photovoltaic program of materials was examined. The current process of producing silicon sheets is based entirely on the conventional Czochralski ingot growth and wafering used in the semiconductor industry. The current technology cannot meet the cost reduction demands for producing low cost silicon sheets. Alternative sheet production processes such as unconventional crystallization are needed. The production of polycrystalline silicon sheets by unconventional ingot technology is the casting technique. Though large grain sheets were obtained by this technique, silicon ribbon growth overcomes deficiencies of the casting process by obtaining the sheet directly from the melt. The need to solve difficulties of growth stability and impurity effects are examined. The direct formation process of polycrystalline silicon sheets with large grain size, smooth surface, and sharp edges from the melt with a high growth rate which will yield low cost silicon sheets for solar cells and the photovoltaic characteristics associated with this type of sheet to include an EBIC study of the grain boundaries are described.

  17. Improvement in passivation quality and open-circuit voltage in silicon heterojunction solar cells by the catalytic doping of phosphorus atoms

    NASA Astrophysics Data System (ADS)

    Tsuzaki, Shogo; Ohdaira, Keisuke; Oikawa, Takafumi; Koyama, Koichi; Matsumura, Hideki

    2015-07-01

    We apply phosphorus (P) doping to amorphous silicon (a-Si)/crystalline silicon (c-Si) heterojunction solar cells realized by exposing c-Si to P-related radicals generated by the catalytic cracking of PH3 molecules (Cat-doping). An ultrathin n+-layer formed by P Cat-doping acts to improve the effective minority carrier lifetime (τeff) and implied open-circuit voltage (implied Voc) owing to its field effect by which minority holes are sent back from an a-Si/c-Si interface. An a-Si/c-Si heterojunction solar cell with a P Cat-doped layer shows better solar cell performance, particularly in Voc, than the cell without P Cat-doping. This result demonstrates the feasibility of applying Cat-doping to a-Si/c-Si heterojunction solar cells, owing to the advantage of the low-temperature (<200 °C) process of Cat-doping.

  18. Improving efficiency of silicon solar cells using europium-doped silicate-phosphor layer by spin-on film coating

    NASA Astrophysics Data System (ADS)

    Ho, Wen-Jeng; Yang, Guo-Chang; Shen, Yu-Tang; Deng, Yu-Jie

    2016-03-01

    This paper reports impressive enhancements in the efficiency of crystalline silicon solar cells through the application of a Eu-doped silicate phosphor luminescent downshifting (LDS) layer controlled by spin-on film technique. Surface morphology was examined using scanning electron microscope (SEM), chemical composition was analyzed using energy dispersive spectroscopy (EDS), and fluorescence emission was characterized using photoluminescence (PL) measurements at room temperature. The optical reflectance, absorbance, and external quantum efficiency (EQE) response of SiO2-coated cells with and without Eu-doped silicate phosphor were measured and compared. An 18.77% improvement in efficiency was achieved, as determined by photovoltaic current-voltage measurement under one-sun AM 1.5 G illuminations.

  19. AC solar cell

    SciTech Connect

    Schutten, H.P.; Benjamin, J.A.; Lade, R.W.

    1986-03-18

    An AC solar cell is described comprising: a pair of PN junction type solar cells connected in antiparallel between a pair of main terminals; and means for electrically directing light alternatingly without mechanical movement on the PN junctions to generate an alternating potential across the main terminals.

  20. 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.

  1. Development of large area nanostructured silicon-hydrogen alloy material with improved stability for solar cell application by argon dilution method

    NASA Astrophysics Data System (ADS)

    Dey, Arka; Das, Mrinmay; Datta, Joydeep; Jana, Rajkumar; Dhar, Joydeep; Sil, Sayantan; Biswas, Debasish; Banerjee, Chandan; Ray, Partha Pratim

    2016-07-01

    Here we have presented the results of large area (30 × 30 cm2) silicon-hydrogen alloy material and solar cell by argon dilution method. As an alternative to hydrogen dilution, argon dilution method has been applied to develop single junction solar cell with appreciable stability. Optimization of deposition conditions revealed that 95% argon dilution gives a nanostructured material with improved transport property and less light induced degradation. The minority carrier diffusion length (L d ) and mobility-lifetime (μτ) product of the material with 95% argon dilution degrades least after light soaking. Also the density of states (DOS) below conduction level reveals that this material is less defective. Solar cell with this argon diluted material has been fabricated with all the layers deposited by argon dilution method. Finally we have compared the argon diluted solar cell results with the optimized hydrogen diluted solar cell. Light soaking study proves that it is possible to develop stable solar cell on large area by argon dilution method and that the degradation of argon diluted solar cell is less than that of hydrogen diluted one. [Figure not available: see fulltext.

  2. Efficiency-improvement study for GaAs solar cells. Final report, March 31, 1980-September 30, 1981

    SciTech Connect

    Cape, J.A.; Oliver, J.R.; Zehr, S.W.

    1982-04-01

    High-yield fabrication of good quality AlGaAs/GaAs concentration solar cells has been a limiting factor in widespread utilization of these high conversion efficiency (22 to 24%) photovoltaic cells. Reported is a series of investigations to correlate solar cell yield with substrate quality, growth techniques, layer composition, and metallization processes. In addition, several diagnostic techniques are described to aid in device characterization.

  3. Eutectic Contact Inks for Solar Cells

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1985-01-01

    Low-resistance electrical contacts formed on solar cells by melting powders of eutectic composition of semiconductor and dopant. Process improves cell performance without subjecting cell to processing temperatures high enough to degrade other characteristics.

  4. Carbon Nanotube Solar Cells

    PubMed Central

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

  5. 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.

  6. Improved conversion efficiency of InN/p-GaN heterostructure solar cells with embedded InON quantum dots

    NASA Astrophysics Data System (ADS)

    Ke, Wen-Cheng; Liang, Zhong-Yi; Yang, Cheng-Yi; Chan, Yu-Teng; Jiang, Chi-Yung

    2016-02-01

    An indium oxynitride (InON) quantum dot (QD) layer was inserted between the indium nitride (InN) and p-type gallium nitride (GaN) films for improving the conversion efficiency of the heterostructure solar cells. The InN/InON QD/p-GaN heterostructure solar cells exhibited a high open-circuit voltage of 2.29 V, short-circuit current density of 1.64 mA/cm2, and conversion efficiency of 1.12% under AM 1.5G illumination. Compared with samples without InON QDs, the power conversion efficiency of sample with InON QDs increased twofold; this increase was attributed to the increase in short-current density. The external quantum efficiency of 250-nm-thick InN/p-GaN heterostructure solar cells has a highest value of 6.5% in the wavelength range of 700-1100 nm. The photogenerated holes separated in the depletion region of InN thin films is difficult to transport across the energy barrier between the InN and p-GaN layers. The oxygen vacancy assisted carrier transport in the InN/InON QD/p-GaN sample, which was evidenced in its current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The dark I-V characteristic curves in the bias range of -2 to 2 V exhibited ohmic behavior, which indicated the absence of a transport barrier between the InN and p-GaN layers. In addition, a shoulder peak at -0.08 V was observed in the high-frequency (60-100 kHz) C-V characteristic curves corresponding to carrier capture and emission in the shallow defect state of oxygen vacancy in the InON QDs. The oxygen vacancy exists inside the InON QDs and generates the interface states in the InON QD/p-GaN interface to form a carrier transport path. Thus, more photogenerated holes can transport via the InON QDs into the p-GaN layer, contributing to the photocurrent and resulting in high conversion efficiency for the InN/InON QD/p-GaN heterostructure solar cells.

  7. Efficiency Improvement by Transparent Contact Layer in InGaN-Based p-i-n Solar Cells

    NASA Astrophysics Data System (ADS)

    Shim, J. P.; Jeon, S. R.; Lee, D. S.

    2011-12-01

    InGaN/GaN p-i-n solar cells with 10.8% indium composition were fabricated with different current spreading layers and metal-grid electrodes. Ni/Au (5nm/5nm) and ITO (150 nm) were used as a spreading layer for comparison. The solar cell with the ITO current spreading layer showed better results than Ni/Au, a 79.5% fill factor and 1% conversion efficiency. Optimization of the metal-gird electrodes also affected on solar cell efficiency.

  8. Design and development of back reflectors for improved light coupling and absorption enhancement in thin MQW solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Freundlich, Alex

    2015-03-01

    Optimization of non-planar antireflective coating and back- (or front-) surface texturing are widely studied to further reduce the reflection losses and increase the sunlight absorption path in solar cells. Back reflectors have been developed from perfect mirror to textured mirror in order to further increase light path, which can significantly improve the efficiency and allow for much thinner devices. A Lambertian surface, which has the most random texture, can theoretically raise the light path to 4n2 times that of a smooth surface. It's a challenge however to fabricate ideal Lambertian texture, especially in a fast and low cost way. In this work we have developed a method to overcome this challenge that combines the use of laser interference lithography (LIL) and selective wet etching. The approach allows for a rapid wafer scale texture processing with sub-wavelength (nano)- scale control of the pattern and the pitch. The technique appears as being particularly attractive for the development of ultra-thin III-V devices, or in overcoming the weak sub-bandgap absorption in devices incorporating quantum dots or quantum wells. Preliminary results on the application of the technique for the development of back reflector for 1-1.3 eV (MQW bearing) GaAs solar cells are presented.

  9. Perovskite Solar Cells: Moth-Eye TiO2 Layer for Improving Light Harvesting Efficiency in Perovskite Solar Cells (Small 18/2016).

    PubMed

    Kang, Seong Min; Jang, Segeun; Lee, Jong-Kwon; Yoon, Jungjin; Yoo, Dong-Eun; Lee, Jin-Wook; Choi, Mansoo; Park, Nam-Gyu

    2016-05-01

    A moth-eye patterned mesoporous (mp) TiO2 layer is fabricated in the form of submicron scale by using lithography, nano-imprinting and polydimethyl siloxane (PDMS) stamping methods. On page 2443, M. Choi, N.-G. Park, and co-workers demonstrate an excellent light harvesting property of perovskite solar cell by employing the moth-eye nanostructured mp-TiO2 film. These novel fabrication methods are expected to be optically beneficial to opto-electronic devices. PMID:27151831

  10. Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices

    NASA Astrophysics Data System (ADS)

    Li, Zhe; Ho Chiu, Kar; Shahid Ashraf, Raja; Fearn, Sarah; Dattani, Rajeev; Cheng Wong, Him; Tan, Ching-Hong; Wu, Jiaying; Cabral, João T.; Durrant, James R.

    2015-10-01

    Morphological stability is a key requirement for outdoor operation of organic solar cells. We demonstrate that morphological stability and lifetime of polymer/fullerene based solar cells under thermal stress depend strongly on the substrate interface on which the active layer is deposited. In particular, we find that the stability of benchmark PCDTBT/PCBM solar cells under modest thermal stress is substantially increased in inverted solar cells employing a ZnO substrate compared to conventional devices employing a PEDOT:PSS substrate. This improved stability is observed to correlate with PCBM nucleation at the 50 nm scale, which is shown to be strongly influenced by different substrate interfaces. Employing this approach, we demonstrate remarkable thermal stability for inverted PCDTBT:PC70BM devices on ZnO substrates, with negligible (<2%) loss of power conversion efficiency over 160 h under 85 °C thermal stress and minimal thermally induced “burn-in” effect. We thus conclude that inverted organic solar cells, in addition to showing improved environmental stability against ambient humidity exposure as widely reported previously, can also demonstrate enhanced morphological stability. As such we show that the choice of suitable substrate interfaces may be a key factor in achieving prolonged lifetimes for organic solar cells under thermal stress conditions.

  11. Data supporting the role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells.

    PubMed

    Scuto, Andrea; Valenti, Luca; Pierro, Silvio; Foti, Marina; Gerardi, Cosimo; Battaglia, Anna; Lombardo, Salvatore

    2015-09-01

    Hydrogenated amorphous Si (a-Si:H) solar cells are strongly affected by the well known Staebler-Wronski effect. This is a worsening of solar cell performances under light soaking which results in a substantial loss of cell power conversion efficiency compared to time zero performance. It is believed not to be an extrinsic effect, but rather a basic phenomenon related to the nature of a-Si:H and to the stability and motion of H-related species in the a-Si:H lattice. This work has been designed in support of the research article entitled "Role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells" in Solar Energy Materials & Solar Cells (Scuto et al. [1]), which discusses an electrical method based on reverse bias stress to improve the solar cell parameters, and in particular the effect of temperature, electric field intensity and illumination level as a function of the stress time. Here we provide a further set of the obtained experimental data results. PMID:26966715

  12. Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices

    PubMed Central

    Li, Zhe; Ho Chiu, Kar; Shahid Ashraf, Raja; Fearn, Sarah; Dattani, Rajeev; Cheng Wong, Him; Tan, Ching-Hong; Wu, Jiaying; Cabral, João T.; Durrant, James R.

    2015-01-01

    Morphological stability is a key requirement for outdoor operation of organic solar cells. We demonstrate that morphological stability and lifetime of polymer/fullerene based solar cells under thermal stress depend strongly on the substrate interface on which the active layer is deposited. In particular, we find that the stability of benchmark PCDTBT/PCBM solar cells under modest thermal stress is substantially increased in inverted solar cells employing a ZnO substrate compared to conventional devices employing a PEDOT:PSS substrate. This improved stability is observed to correlate with PCBM nucleation at the 50 nm scale, which is shown to be strongly influenced by different substrate interfaces. Employing this approach, we demonstrate remarkable thermal stability for inverted PCDTBT:PC70BM devices on ZnO substrates, with negligible (<2%) loss of power conversion efficiency over 160 h under 85 °C thermal stress and minimal thermally induced “burn-in” effect. We thus conclude that inverted organic solar cells, in addition to showing improved environmental stability against ambient humidity exposure as widely reported previously, can also demonstrate enhanced morphological stability. As such we show that the choice of suitable substrate interfaces may be a key factor in achieving prolonged lifetimes for organic solar cells under thermal stress conditions. PMID:26468676

  13. Improved efficiency and stability of flexible dye sensitized solar cells on ITO/PEN substrates using an ionic liquid electrolyte.

    PubMed

    Han, Yu; Pringle, Jennifer M; Cheng, Yi-Bing

    2015-01-01

    Flexible dye-sensitized solar cells (DSSCs) built on plastic substrates have attracted great interest as they are lightweight and can be roll-to-roll printed to accelerate production and reduce cost. However, plastic substrates such as PEN and PET are permeable to water, oxygen and volatile electrolyte solvents, which is detrimental to the cell stability. Therefore, to address this problem, in this work, an ionic liquid (IL) electrolyte is used to replace the volatile solvent electrolyte. The initial IL-based devices only achieved around 50% of the photovoltaic conversion efficiency of the cells using the solvent electrolyte. Current-voltage and electrochemical impedance spectroscopy (EIS) analysis of the cells in the dark indicated that this lower efficiency mainly originated from (i) a lack of blocking layer to reduce recombination, and (ii) a lower charge collection efficiency. To combat these problems, cells were developed using a 12 nm thick blocking layer, produced by atomic layer deposition, and 1 μm thick P25 TiO2 film sensitized with the hydrophobic MK-2 dye. These flexible DSSCs utilizing an IL electrolyte exhibit significantly improved efficiencies and a <10% drop in performance after 1000 h aging at 60°C under continuous light illumination. PMID:25476521

  14. 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

  15. Bilayer film electrode of brookite TiO2 particles with different morphology to improve the performance of pure brookite-based dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Jinlei; Wu, Shufang; Ri, Jin Hyok; Jin, Jingpeng; Peng, Tianyou

    2016-09-01

    A novel bilayer brookite TiO2 film photoanode consisting of quasi nanocube film as underlayer and rice-like submicrometer particle film as overlayer are fabricated for improving the photovoltaic properties of the pure brookite-based dye-sensitized solar cells (DSSCs). The brookite TiO2 nanocubes have a mean size of ∼50 nm, and the brookite TiO2 rice-like particles have diameter of ∼600 nm and length of ∼1100 nm. An optimal photovoltaic conversion efficiency of 5.51% is obtained from the bilayer brookite-based solar cell, with ∼41% improvement in the efficiency as compared to the single brookite nanocube film-based one (3.91%) under AM 1.5G one sun irradiation. The bilayer brookite-based solar cell shows not only reduced charge recombination and dark current, but also prolonged electron lifetime compared to the single brookite nanocube film-based one. All these lead to a higher photocurrent and voltage, and then to the improved efficiency of the brookite-based solar cell. The present results demonstrate a clear advance towards efficient improvement of the photovoltaic performance of pure brookite-based solar cells.

  16. Crystalline Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Green, Martin A.

    2015-10-01

    The following sections are included: * Overview * Silicon cell development * Substrate production * Cell processing * Cell costs * Opportunities for improvement * Silicon-supported thin films * Summary * Acknowledgement * References

  17. Solar cell activation system

    SciTech Connect

    Apelian, L.

    1983-07-05

    A system for activating solar cells involves the use of phosphorescent paint, the light from which is amplified by a thin magnifying lens and used to activate solar cells. In a typical system, a member painted with phosphorescent paint is mounted adjacent a thin magnifying lens which focuses the light on a predetermined array of sensitive cells such as selenium, cadmium or silicon, mounted on a plastic board. A one-sided mirror is mounted adjacent the cells to reflect the light back onto said cells for purposes of further intensification. The cells may be coupled to rechargeable batteries or used to directly power a small radio or watch.

  18. Towards stable silicon nanoarray hybrid solar cells

    PubMed Central

    He, W. W.; Wu, K. J.; Wang, K.; Shi, T. F.; Wu, L.; Li, S. X.; Teng, D. Y.; Ye, C. H.

    2014-01-01

    Silicon nanoarray hybrid solar cells benefit from the ease of fabrication and the cost-effectiveness of the hybrid structure, and represent a new research focus towards the utilization of solar energy. However, hybrid solar cells composed of both inorganic and organic components suffer from the notorious stability issue, which has to be tackled before the hybrid solar cells could become a viable alternative for harvesting solar energy. Here we show that Si nanoarray/PEDOT:PSS hybrid solar cells with improved stability can be fabricated via eliminating the water inclusion in the initial formation of the heterojunction between Si nanoarray and PEDOT:PSS. The Si nanoarray hybrid solar cells are stable against rapid degradation in the atmosphere environment for several months without encapsulation. This finding paves the way towards the real-world applications of Si nanoarray hybrid solar cells. PMID:24430057

  19. 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

  20. Dye sensitized solar cells.

    PubMed

    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 TiO(2), 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

    SciTech Connect

    Tada, H.Y.; Carter, J.R. Jr.; Anspaugh, B.E.

    1982-11-01

    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. 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.

  3. Data supporting the role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells

    PubMed Central

    Scuto, Andrea; Valenti, Luca; Pierro, Silvio; Foti, Marina; Gerardi, Cosimo; Battaglia, Anna; Lombardo, Salvatore

    2015-01-01

    Hydrogenated amorphous Si (a­Si:H) solar cells are strongly affected by the well known Staebler–Wronski effect. This is a worsening of solar cell performances under light soaking which results in a substantial loss of cell power conversion efficiency compared to time zero performance. It is believed not to be an extrinsic effect, but rather a basic phenomenon related to the nature of a­Si:H and to the stability and motion of H­related species in the a­Si:H lattice. This work has been designed in support of the research article entitled “Role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells” in Solar Energy Materials & Solar Cells (Scuto et al. [1]), which discusses an electrical method based on reverse bias stress to improve the solar cell parameters, and in particular the effect of temperature, electric field intensity and illumination level as a function of the stress time. Here we provide a further set of the obtained experimental data results. PMID:26966715

  4. Improvement of Si Adhesion and Reduction of Electron Recombination for Si Quantum Dot-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Wang, Yuting; Sato, Muneharu; Uchida, Giichiro; Kamataki, Kunihiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2013-01-01

    Quantum dots (QDs) based on multiple exciton generation have attracted much attention. They are capable of generating multiple electrons by single-photon absorption. Si is one of the good QD sources and its nontoxicity and abundance are advantageous for photovoltaics. In this work, Si QDs were fabricated by multihollow discharge plasma chemical vapor deposition, and they were applied to Si QD-sensitized solar cells. Their initial performance was poor because of the weak adhesion of Si and charge recombination. In this work, we solved these problems through the functionalization of Si QDs and a ZnO barrier. Functionalized Si QDs were more adsorbed on TiO2 with strengthened adhesion and the ZnO barrier prevented the contact between TiO2 and the redox electrolyte. Consequently, the improved adhesion and the reduced electron recombination led to the enhancement of overall photovoltaic characteristics.

  5. Dye decorated ZnO-NWs /CdS-NPs heterostructures for efficiency improvement of quantum dots sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Nayeri, Fatemeh Dehghan; Akbarnejad, Elaheh; Ghoranneviss, Mahmood; Soleimani, Ebrahim Asl; Hashemizadeh, S. A.

    2016-03-01

    High density vertically aligned ZnO nanowire was coated with CdS nanocrystals of different thicknesses by the RF magnetron sputtering process and applied as photoanode in CdS quantum dot sensitized solar cells. Field emission scanning electron microscopy (FESEM), photoluminescence, and X-Ray diffraction (XRD) were utilized to characterize the samples and study their properties. Results demonstrated that, after dye decoration co-sensitized process, the ZnO/CdS heterostructures showed an overall power conversion efficiency of 2.68%, which is 76.3% improvement over that of pristine ZnO/CdS-QDSSC. Thereby, the QDSSC was assembled with modified ZnO/CdS heterostructures by Dye exhibited high performance.

  6. Improved hole mobility and suppressed trap density in polymer-polymer dual donor based highly efficient organic solar cells

    NASA Astrophysics Data System (ADS)

    Bharti, Vishal; Sharma, Abhishek; Gupta, Vinay; Sharma, Gauri D.; Chand, Suresh

    2016-02-01

    Here we report, the charge transport properties of polymer-polymer dual donor blended film, viz., polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) and poly [N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'benzothiadiazole) (PCDTBT) in the optimized concentration. Trap density and hole mobility in polymer-polymer (PTB7-PCDTBT) dual donor system have been studied by means of current density-voltage (J-V) characteristics at various temperatures, i.e., 280 K-120 K in hole only device configuration, i.e., indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT:PSS)/Polymer film/gold (Au). The J-V curves exhibit the space charge limited conduction behavior. The corresponding hole mobility for PTB7 and PCDTBT are 3.9 × 10-4 cm2 V-1 s-1 and 2.1 × 10-4 cm2 V-1 s-1, respectively, whereas it is 9.1 × 10-4 cm2 V-1 s-1 in the polymer-polymer blend of PTB7:PCDTBT (0.7:0.3). This enhancement in mobility can be attributed to the suppressed trap density in PTB7:PCDTBT (0.7:0.3) of 7.4 × 1016 cm-3, as compared to the trap density of 1.1 × 1017 cm-3 for PTB7 and 1.6 × 1017 cm-3 for PCDTBT. Atomic force microscopy shows an improvement in the morphology of the blend. The J-V characteristic at various light intensities in the bulk heterojunction (BHJ) solar cell reveals that the blending of PCDTBT in PTB7 suppressed the trap-assisted recombination. The corresponding power conversion efficiencies for PTB7:PC71BM, PCDTBT:PC71BM and PTB7:PCDTBT:PC71BM BHJ solar cells are 6.9%, 6.1% and 9.0%, respectively. This work unravels that the enhanced mobility and suppressed trap density play a significant role in the improvement of efficiency in dual donor based organic solar cells.

  7. Extended Temperature Solar Cell Technology Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Jenkins, Phillip; Scheiman, David; Rafaelle, Ryne

    2004-01-01

    Future NASA missions will require solar cells to operate both in regimes closer to the sun, and farther from the sun, where the operating temperatures will be higher and lower than standard operational conditions. NASA Glenn is engaged in testing solar cells under extended temperature ranges, developing theoretical models of cell operation as a function of temperature, and in developing technology for improving the performance of solar cells for both high and low temperature operation.

  8. N/P GaAs concentrator solar cells with an improved grid and bushbar contact design

    NASA Technical Reports Server (NTRS)

    Desalvo, G. C.; Mueller, E. H.; Barnett, A. M.

    1985-01-01

    The major requirements for a solar cell used in space applications are high efficiency at AMO irradiance and resistance to high energy radiation. Gallium arsenide, with a band gap of 1.43 eV, is one of the most efficient sunlight to electricity converters (25%) when the the simple diode model is used to calculate efficiencies at AMO irradiance, GaAs solar cells are more radiation resistant than silicon solar cells and the N/P GaAs device has been reported to be more radiation resistant than similar P/N solar cells. This higher resistance is probably due to the fact that only 37% of the current is generated in the top N layer of the N/P cell compared to 69% in the top layer of a P/N solar cell. This top layer of the cell is most affected by radiation. It has also been theoretically calculated that the optimized N/P device will prove to have a higher efficiency than a similar P/N device. The use of a GaP window layer on a GaAs solar cell will avoid many of the inherent problems normally associated with a GaAlAs window while still proving good passivation of the GaAs surface. An optimized circular grid design for solar cell concentrators has been shown which incorporates a multi-layer metallization scheme. This multi-layer design allows for a greater current carrying capacity for a unit area of shading, which results in a better output efficiency.

  9. Current status of silicon solar cell technology

    NASA Technical Reports Server (NTRS)

    Brandhorst, H. W., Jr.

    1975-01-01

    In quest of higher efficiency, major progress has occurred in solar cell technology. Cell efficiency has climbed about 50 percent. Technical approaches leading to increased output include back surface fields, shallow junctions, improved antireflection coatings, surface texturizing, and fine grid patterns on the cell surface. The status of current solar cell technology and its incorporation into cell production is discussed. Research and development leading to improved performance and reduced cost are also described.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Lightweight solar cell

    SciTech Connect

    Hotaling, S.P.

    1993-06-22

    A lightweight solar cell is described comprising: (a) an LD aerogel substrate having a density of between 10-1,000 mg/cc, the surface of the substrate being polished (b) a dielectric planarization layer being applied to the polished surface, and (c) at least one layer of PV material deposited thereon. The solar cell having a plurality of PV layers deposited on the planarization layer.

  16. 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…

  17. Sliver solar cells

    NASA Astrophysics Data System (ADS)

    Franklin, Evan; Blakers, Andrew; Everett, Vernie; Weber, Klaus

    2007-12-01

    Sliver solar cells are thin, mono-crystalline silicon solar cells, fabricated using micro-machining techniques combined with standard solar cell fabrication technology. Sliver solar modules can be efficient, low cost, bifacial, transparent, flexible, shadow-tolerant, and lightweight. Sliver modules require only 5 to 10% of the pure silicon and less than 5% of the wafer starts per MW p of factory output when compared with conventional photovoltaic modules. At ANU, we have produced 20% efficient Sliver solar cells using a robust, optimised cell fabrication process described in this paper. We have devised a rapid, reliable and simple method for extracting Sliver cells from a Sliver wafer, and methods for assembling modularised Sliver cell sub-modules. The method for forming these Sliver sub-modules, along with a low-cost method for rapidly forming reliable electrical interconnections, are presented. Using the sub-module approach, we describe low-cost methods for assembling and encapsulating Sliver cells into a range of module designs.

  18. 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.

  19. Screening of solar cells

    SciTech Connect

    Appelbaum, J.; Chait, A.; Thompson, D.A.

    1993-07-01

    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.

  20. Trace surface-clean palladium nanosheets as a conductivity enhancer in hole-transporting layers to improve the overall performances of perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Cao, Jing; Mo, Shiguang; Jing, Xiaojing; Yin, Jun; Li, Jing; Zheng, Nanfeng

    2016-02-01

    Surface-clean Pd nanosheets were synthesized and embedded in a hole transport material (HTM) matrix to improve the conductivity of the HTM layer. Applying only a trace amount of Pd nanosheets readily led to a remarkably enhanced performance of perovskite solar cells (PSCs). This finding provides an effective strategy to build efficient charge-transport materials for improving the overall performance of PSCs.Surface-clean Pd nanosheets were synthesized and embedded in a hole transport material (HTM) matrix to improve the conductivity of the HTM layer. Applying only a trace amount of Pd nanosheets readily led to a remarkably enhanced performance of perovskite solar cells (PSCs). This finding provides an effective strategy to build efficient charge-transport materials for improving the overall performance of PSCs. Electronic supplementary information (ESI) available: Details of the XRD, UV-vis spectra, cross-sectional SEM images and the EQE spectra of the cells. See DOI: 10.1039/c5nr07789c

  1. Silicon concentrator solar cell research

    SciTech Connect

    Green, M.A.; Zhao, J.; Wang, A.; Dai, X.; Milne, A.; Cai, S.; Aberle, A.; Wenham, S.R.

    1993-06-01

    This report describes work conducted between December 1990 and May 1992 continuing research on silicon concentrator solar cells. The objectives of the work were to improve the performance of high-efficiency cells upon p-type substrates, to investigate the ultraviolet stability of such cells, to develop concentrator cells based on n-type substrates, and to transfer technology to appropriate commercial environments. Key results include the identification of contact resistance between boron-defused areas and rear aluminum as the source of anomalously large series resistance in both p- and n-type cells. A major achievement of the present project was the successful transfer of cell technology to both Applied Solar Energy Corporation and Solarex Corporation.

  2. Nanostructured Materials for Solar Cells

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Raffaelle, Ryne; Castro, Stephanie; Fahey, S.; Gennett, T.; Tin, P.

    2003-01-01

    The use of both inorganic and organic nanostructured materials in producing high efficiency photovoltaics is discussed in this paper. Recent theoretical results indicate that dramatic improvements in device efficiency may be attainable through the use of semiconductor quantum dots in an ordinary p-i-n solar cell. In addition, it has also recently been demonstrated that quantum dots can also be used to improve conversion efficiencies in polymeric thin film solar cells. A similar improvement in these types of cells has also been observed by employing single wall carbon nanotubes. This relatively new carbon allotrope may assist both in the disassociation of excitons as well as carrier transport through the composite material. This paper reviews the efforts that are currently underway to produce and characterize these nanoscale materials and to exploit their unique properties.

  3. Development of concentrator solar cells

    SciTech Connect

    Not Available

    1994-08-01

    A limited pilot production run on PESC silicon solar cells for use at high concentrations (200 to 400 suns) is summarized. The front contact design of the cells was modified for operation without prismatic covers. The original objective of the contract was to systematically complete a process consolidation phase, in which all the, process improvements developed during the contract would be combined in a pilot production run. This pilot run was going to provide, a basis for estimating cell costs when produced at high throughput. Because of DOE funding limitations, the Photovoltaic Concentrator Initiative is on hold, and Applied Solar`s contract was operated at a low level of effort for most of 1993. The results obtained from the reduced scope pilot run showed the effects of discontinuous process optimization and characterization. However, the run provided valuable insight into the technical areas that can be optimized to achieve the original goals of the contract.

  4. Improved performance of CuInS2 quantum dot-sensitized solar cells based on a multilayered architecture.

    PubMed

    Chang, Jia-Yaw; Lin, Jie-Mo; Su, Li-Fong; Chang, Chia-Fu

    2013-09-11

    This article describes a CuInS2 quantum dot (QD)-sensitized solar cell (QDSSC) with a multilayered architecture and a cascaded energy-gap structure fabricated using a successive ionic-layer adsorption and reaction process. We initially used different metal chalcogenides as interfacial buffer layers to improve unmatched band alignments between the TiO2 and CuInS2 QD sensitizers. In this design, the photovoltaic performance, in terms of the short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE), was significantly improved. Both JSC and VOC were improved in CuInS2-based QDSSCs in the presence of interfacial buffer layers because of proper band alignment across the heterointerface and the negative band edge movement of TiO2. The PCE of CuInS2-based QDSSCs containing In2Se3 interfacial buffer layers was 1.35%, with JSC=5.83 mA/cm2, VOC=595 mV, and FF=39.0%. We also examined the use of alternative CdS and CdSe hybrid-sensitized layers, which were sequentially deposited onto the In2Se3/CuInS2 configuration for creating favorable cascaded energy-gap structures. Both JSC (11.3 mA cm(-2)) and FF (47.3%) for the CuInS2/CdSe hybrid-sensitized cells were higher than those for CuInS2-based cells (JSC=5.83 mA cm(-2) and FF=39.0%). In addition, the hybrid-sensitized cells had PCEs that were 1.3 times those of cells containing identically pretreated In2Se3 interfacial buffer layers. Additionally, we determined that ZnSe served as a good passivation layer on the surface of CuInS2/CdSe hybrid-sensitized QDs, prevented current leakage from the QDs to electrolytes, and lowered interfacial charge recombination. Under simulated illumination (AM 1.5, 100 mW cm(-2)), multilayered QDSSCs with distinct architectures delivered a maximum external quantum efficiency of 80% at 500 nm and a maximum PCE of 4.55%, approximately 9 times that of QDSSCs fabricated with pristine CuInS2. PMID:23937511

  5. Density-controlled ZnO/TiO2 nanocomposite photoanode for improving dye-sensitized solar cells performance

    NASA Astrophysics Data System (ADS)

    Yao, Jimmy; Lin, Chih-Min; Yin, Stuart (.

    2015-03-01

    Dye-sensitized solar cells (DSSCs) via ZnO/TiO2 nanocomposite photoanode with density-controlled abilities are presented in this paper. This nanocomposite photoanode is composed of TiO2 nanoparticles dispersed into densitycontrolled vertically aligned ZnO-TiO2 core-shell nanorod arrays. The density-controlled ZnO-TiO2 core-shell nanorod arrays were synthesized directly onto fluorine-doped tin oxide (FTO) substrates using an innovative two-step wet chemical route. First, the density-controlled ZnO nanorod arrays were formed by applying a ZnO hydrothermal process from a TiO2 nanocrystals template. Second, the ZnO-TiO2 core-shell nanorod arrays were formed by depositing a TiO2 shell layer from a sol-gel process. The major advantages of a density-controlled ZnO/TiO2 nanocomposite photoanode include (1) providing a better diffusion path from ZnO nanorod arrays and (2) reducing the recombination loss by introducing an energy barrier layer TiO2 conformal shell coating. To validate the advantages of a density-controlled ZnO/TiO2 nanocomposite photoanode, DSSCs based on a ZnO/TiO2 nanocomposite photoanode were fabricated, in which N719 dye was used. The average dimensions of the ZnO nanorod arrays were 20 μm and 650 nm for the length and the diameter, respectively, while the designated spacing between each nanorod was around 5 μm. The performance of the solar cell was tested by using a standard AM 1.5 solar simulator from Newport Corporation. The experimental results confirmed that an open-circuit voltage, 0.93 V, was achieved, which was much higher than the conventional TiO2 nanoparticles thin film structure for the same thickness. Thus, density-controlled ZnO/TiO2 nanocomposite photoanodes could improve the performance of DSSCs by offering a better electron diffusion path.

  6. Rare earth organic complexes as down-shifters to improve Si-based solar cell efficiency

    NASA Astrophysics Data System (ADS)

    Le Donne, A.; Dilda, M.; Crippa, M.; Acciarri, M.; Binetti, S.

    2011-05-01

    This work reports on the optical and electrical characterization of crystalline silicon based solar modules encapsulated with ethylene-vinyl-acetate layers (that is the encapsulating matrix used nowadays by the photovoltaic industry) doped with a single europium complex whose sensitized region is broadened due to the presence of a co-ligand. Such europium doped EVA layers are able to realize down-shifting of photons with wavelength lower than 460 nm without introducing modifications of the industrial process leading to the fabrication of the photovoltaic modules. This effect has been proven under Air Mass 1.5 conditions (simulating terrestrial applications), where a 2.9% relative increase of the total power delivered by the encapsulated modules has been observed, allowing a reduction in the watt-peak price.

  7. Improvement of Charge Collection and Performance Reproducibility in Inverted Organic Solar Cells by Suppression of ZnO Subgap States.

    PubMed

    Wu, Bo; Wu, Zhenghui; Yang, Qingyi; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Cheung, Sin-Hang; So, Shu-Kong

    2016-06-15

    Organic solar cells (OSCs) with inverted structure usually exhibit higher power conversion efficiency (PCE) and are more stable than corresponding devices with regular configuration. Indium tin oxide (ITO) surface is often modified with solution-processed low work function metal oxides, such as ZnO, serving as the transparent cathode. However, the defect-induced subgap states in the ZnO interlayer hamper the efficient charge collection and the performance reproducibility of the OSCs. In this work, we demonstrate that suppression of the ZnO subgap states by modification of its surface with an ultrathin Al layer significantly improves the charge extraction and performance reproducibility, achieving PCE of 8.0%, which is ∼15% higher than that of a structurally identical control cell made with a pristine ZnO interlayer. Light intensity-dependent current density-voltage characteristic, photothermal deflection spectroscopy, and X-ray photoelectron spectroscopy measurements point out the enhancement of charge collection efficiency at the organic/cathode interface, due to the suppression of the subgap states in the ZnO interlayer. PMID:27224960

  8. The improved efficiency of low molecular weight organic solar cells doped with a Cu(I) triplet material

    NASA Astrophysics Data System (ADS)

    Su, Bin; Gao, Lin; Li, Xiuying; Che, Guangbo; Zhu, Enwei; Wang, Bo; Yan, Yongsheng

    2016-08-01

    We developed a method to improve the performance of the copper phthalocyanine (CuPc)/fullerene (C60) organic solar cells (OSCs) by doping CuPc with a long triplet lifetime material. By doping [Cu(bis[2-(diphenylphosphino)phenyl]ether)(benzo[i]dipyrido[3,2-a:2',3'-c]phenazine)]BF4 (CuDB) into CuPc, the enhanced short-circuit current density ( J SC) of 6.213 mA/cm2, open-circuit voltage ( V OC) of 0.39 V and a peak power conversion efficiency (PCE) of 0.92% compared to 0.79% of the standard CuPc/C60 OSCs are achieved under 1 sun AM 1.5 G illumination at an intensity of 100 mW/cm2. The performance improvement is mainly attributed to the long triplet lifetime of CuDB (τ = 70.05 μs) which leads to more effective exciton dissociation.

  9. An organosilane self-assembled monolayer incorporated into polymer solar cells enabling interfacial coherence to improve charge transport.

    PubMed

    Li, Zhiqi; Zhang, Xinyuan; Zhang, Zhihui; Li, Shujun; Liu, Chunyu; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-06-21

    The reproducible silylation of titanium oxide (TiO2) with small molecular (dichloromethyl) dimethylchlorosilane (DCS) as the cathode buffer layer was developed to improve electron extraction. Through incorporating the DCS capping layer into polymer solar cells (PSCs), the interfacial coherence of devices could be enhanced, leading to a shift in nanocrystallite size and a smaller internal charge transport resistance. Furthermore, a TiO2/DCS combined interfacial layer could serve as both an exciton dissociation center and a charge transfer channel, which results in a reduction in the energy barrier and electron loss, improving hole-blocking and surface-state passivation in the TiO2 interfacial layer. The Kelvin probe measurements demonstrate that the employment of the DCS nanolayer decreases conduction band energy of TiO2via forming a dipole layer at the interface of TiO2 and the DCS nanolayer, which tunes the work-function of the device and ulteriorly enhances charge carrier transfer between the electrode and the active layer. As a result, the photocurrent and the fill factor of the PSCs are both increased, resulting in an increased power conversion efficiency (PCE) of 6.959%. PMID:27242077

  10. 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.

  11. Parameterization of solar cells

    NASA Astrophysics Data System (ADS)

    Appelbaum, J.; Chait, A.; Thompson, D.

    1992-10-01

    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.

  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. Improving the efficiency of polymer solar cells based on furan-flanked diketopyrrolopyrrole copolymer via solvent additive and methanol treatment

    NASA Astrophysics Data System (ADS)

    Zhou, Weilong; Chen, Huajie; Lv, Junjie; Chen, Youchun; Zhang, Weifeng; Yu, Gui; Li, Fenghong

    2015-09-01

    We present a furan-flanked DPP copolymer, poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo [3,4-c]pyrrole-1,4-dione-altthienylenevinylene} (PDVF-8), and highlight the improvement in the power conversion efficiency (PCE) of polymer solar cells (PSCs) based on the PDVF-8 as an electron donor via solvent additive and methanol treatment. When 3 vol% 1,8-diiodooctane (DIO) or 1-chloronaphthalene (CN) were used as a solvent additive to the PDVF-8:PC71BM solution in chloroform (CF), the PCE can increase from 0.79% to 3.73% or 4.26%. Methanol treatment (MT) can further enhance the PCE to 4.03% (DIO) and 4.69% (CN). The effect of the solvent additives (DIO and CN) and MT on the phase separation of the PDVF-8:PC71BM thin film has been investigated in detail using atomic force microscopy, transmission electron microscopy (TEM), TEM-energy dispersive spectroscopy and X-ray photoemission spectroscopy depth profiling.We present a furan-flanked DPP copolymer, poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo [3,4-c]pyrrole-1,4-dione-altthienylenevinylene} (PDVF-8), and highlight the improvement in the power conversion efficiency (PCE) of polymer solar cells (PSCs) based on the PDVF-8 as an electron donor via solvent additive and methanol treatment. When 3 vol% 1,8-diiodooctane (DIO) or 1-chloronaphthalene (CN) were used as a solvent additive to the PDVF-8:PC71BM solution in chloroform (CF), the PCE can increase from 0.79% to 3.73% or 4.26%. Methanol treatment (MT) can further enhance the PCE to 4.03% (DIO) and 4.69% (CN). The effect of the solvent additives (DIO and CN) and MT on the phase separation of the PDVF-8:PC71BM thin film has been investigated in detail using atomic force microscopy, transmission electron microscopy (TEM), TEM-energy dispersive spectroscopy and X-ray photoemission spectroscopy depth profiling. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04393j

  14. Improve efficiency of perovskite solar cells by using Magnesium doped ZnO and TiO2 compact layers

    NASA Astrophysics Data System (ADS)

    Baktash, Ardeshir; Amiri, Omid; Sasani, Alireza

    2016-05-01

    Here the effect of Magnesium doped TiO2 and ZnO as hole blocking layers (HBLs) are investigated by using solar cell capacitance simulator (SCAPS). The Impact of Magnesium concentration into the TiO2 and ZnO and effect of operating temperature on the performance of the perovskite solar cell are investigated. Best cell performance for both TiO2 and ZnO HBLs (with cell efficiencies of 19.86% and 19.57% respectively) are concluded for the doping level of 10% of Mg into the structure of HBLs. Increase in operating temperature from 300 K to 400 K are decreased the performance of the perovskite solar cell with both pure and Mg-doped HBLs. However, the cells with pure ZnO layer and with Zn0.9 Mg0.1O layer show the highest (with a decline of 8.88% in efficiency) and the lowest stability (with a decline of 50.49% in efficiency) at higher temperatures respectively. Moreover, the cell with Ti0.9 Mg0.1O2 layer shows better stability (with 21.85% reduction in efficiency) than the cell with pure TiO2 compact layer (with 23.28% reduction in efficiency) at higher operating temperatures.

  15. Towards a CdS/Cu{sub 2}ZnSnS{sub 4} solar cell efficiency improvement: A theoretical approach

    SciTech Connect

    Courel, Maykel Andrade-Arvizu, J. A.; Vigil-Galán, O.

    2014-12-08

    In this work, a device model for Cu{sub 2}ZnSnS{sub 4} (CZTS) solar cell with certified world record efficiency is presented. A study of the most important loss mechanisms and its effect on solar cell performance was carried out. The trap-assisted tunneling and CdS/CZTS interface recombination are introduced as the most important loss mechanisms. Detailed comparison of the simulation results to the measured device parameters shows that our model is able to reproduce the experimental observations (quantum efficiency, efficiency, J{sub sc}, FF, and V{sub oc}) reported under normal operating conditions. Finally, a discussion about a further solar cell efficiency improvement is addressed.

  16. Improved Ga grading of sequentially produced Cu(In,Ga)Se{sub 2} solar cells studied by high resolution X-ray fluorescence

    SciTech Connect

    Schöppe, Philipp; Schnohr, Claudia S.; Oertel, Michael; Kusch, Alexander; Johannes, Andreas; Eckner, Stefanie; Reislöhner, Udo; Ronning, Carsten; Burghammer, Manfred; Martínez-Criado, Gema

    2015-01-05

    There is particular interest to investigate compositional inhomogeneity of Cu(In,Ga)Se{sub 2} solar cell absorbers. We introduce an approach in which focused ion beam prepared thin lamellas of complete solar cell devices are scanned with a highly focused synchrotron X-ray beam. Analyzing the resulting fluorescence radiation ensures high resolution compositional analysis combined with high spatial resolution. Thus, we are able to detect subtle variations of the Ga/(Ga + In) ratio down to 0.01 on a submicrometer scale. We observed that for sequentially processed solar cells a higher selenization temperature leads to absorbers with almost homogenous Ga/(Ga + In) ratio, which significantly improved the conversion efficiency.

  17. Structure, Optical Absorption, and Performance of Organic Solar Cells Improved by Gold Nanoparticles in Buffer Layers.

    PubMed

    Yang, Yingguo; Feng, Shanglei; Li, Meng; Wu, Zhongwei; Fang, Xiao; Wang, Fei; Geng, Dongping; Yang, Tieying; Li, Xiaolong; Sun, Baoquan; Gao, Xingyu

    2015-11-11

    11-Mercaptoundecanoic acid (MUA)-stabilized gold nanoparticles (AuNPs) embedded in copper phthalocyanine (CuPc) were used as a buffer layer between a poly(3-hexyl-thiophene) (P3HT)/[6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction and anodic indium-tin oxide (ITO) substrate. As systematic synchrotron-based grazing incidence X-ray diffraction (GIXRD) experiments demonstrated that the AuNPs present in the buffer layer can improve the microstructure of the active layer with a better lamella packing of P3HT from the surface to the interior, UV-visible absorption spectrum measurements revealed enhanced optical absorption due to the localized surface plasma resonance (LSPR) generated by the AuNPs. The device of ITO/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/CuPc:MUA-stabilized AuNPs/P3HT:PCBM/LiF/Al was found with over 24% enhancement of power conversion efficiency (PCE) in comparison with reference devices without AuNPs. This remarkable improvement in PCE should be partially attributed to LSPR generated by the AuNPs and partially to improved crystallization as well as preferred orientation order of P3HT due to the presence of the AuNPs, which would promote more applications of metal NPs in the organic photovoltaic devices and other organic multilayer devices. PMID:26477556

  18. Characterization of anthocyanin based dye-sensitized organic solar cells (DSSC) and modifications based on bio-inspired ion mobility improvements

    NASA Astrophysics Data System (ADS)

    Mawyin, Jose Amador

    The worldwide electrical energy consumption will increase from currently 10 terawatts to 30 terawatts by 2050. To decrease the current atmospheric CO2 would require our civilization to develop a 20 terawatts non-greenhouse emitting (renewable) electrical power generation capability. Solar photovoltaic electric power generation is thought to be a major component of proposed renewable energy-based economy. One approach to less costly, easily manufactured solar cells is the Dye-sensitized solar cells (DSSC) introduced by Greatzel and others. This dissertation describes the work focused on improving the performance of DSSC type solar cells. In particular parameters affecting dye-sensitized solar cells (DSSC) based on anthocyanin pigments extracted from California blackberries (Rubus ursinus) and bio-inspired modifications were analyzed and solar cell designs optimized. Using off-the-shelf materials DSSC were constructed and tested using a custom made solar spectrum simulator and photoelectric property characterization. This equipment facilitated the taking of automated I-V curve plots and the experimental determination of parameters such as open circuit voltage (V OC), short circuit current (JSC), fill factor (FF), etc. This equipment was used to probe the effect of various modifications such as changes in the annealing time and composition of the of the electrode counter-electrode. Solar cell optimization schemes included novel schemes such as solar spectrum manipulation to increase the percentage of the solar spectrum capable of generating power in the DSSC. Solar manipulation included light scattering and photon upconversion. Techniques examined here focused on affordable materials such as silica nanoparticles embedded inside a TiO2 matrix. Such materials were examined for controlled scattering of visible light and optimize light trapping within the matrix as well as a means to achieve photon up-energy-conversion using the Raman effect in silica nano-particles (due

  19. 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.

  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. 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.

  2. Improvement of Thiolate/Disulfide Mediated Dye-Sensitized Solar Cells through Supramolecular Lithium Cation Assembling of Crown Ether

    PubMed Central

    Liu, Linfeng; Li, Xiong; Chen, Jiangzhao; Rong, Yaoguang; Ku, Zhiliang; Han, Hongwei

    2013-01-01

    A supramolecular lithium cation assemblies of crown ether, [Li⊂12-crown-4]+, has been used to replace conventional tetraalkylammonium counterion in thiolate/disulfide (ET−/BET) mediated dye-sensitized solar cells (DSCs), which exhibit high stability and efficiency of 6.61% under 100 mW·cm−2 simulated sunlight illumination. PMID:23933601

  3. Charge Photogeneration Experiments and Theory in Aggregated Squaraine Donor Materials for Improved Organic Solar Cell Efficiencies

    NASA Astrophysics Data System (ADS)

    Spencer, Susan Demetra

    Fossil fuel consumption has a deleterious effect on humans, the economy, and the environment. Renewable energy technologies must be identified and commercialized as quickly as possible so that the transition to renewables can happen at a minimum of financial and societal cost. Organic photovoltaic cells offer an inexpensive and disruptive energy technology, if the scientific challenges of understanding charge photogeneration in a bulk heterojunction material can be overcome. At RIT, there is a strong focus on creating new materials that can both offer fundamentally important scientific results relating to quantum photophysics, and simultaneously assist in the development of strong candidates for future commercialized technology. In this presentation, the results of intensive materials characterization of a series of squaraine small molecule donors will be presented, as well as a full study of the fabrication and optimization required to achieve >4% photovoltaic cell efficiency. A relationship between the molecular structure of the squaraine and its ability to form nanoscale aggregates will be explored. Squaraine aggregation will be described as a unique optoelectronic probe of the structure of the bulk heterojunction. This relationship will then be utilized to explain changes in crystallinity that impact the overall performance of the devices. Finally, a predictive summary will be given for the future of donor material research at RIT.

  4. 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.

  5. Co-sensitization of natural dyes for improved efficiency in dye-sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Kumar, K. Ashok; Subalakshmi, K.; Senthilselvan, J.

    2016-05-01

    In this paper, a new approach of co-sensitized DSSC based on natural dyes is investigated to explore the possible way to improve the power conversion efficiency. To realize this purpose 10 DSSC devices were fabricated using mono-sensitization and co-sensitization of ethanolic extracts of natural dye sensitizers obtained from Cactus fruit, Jambolana fruit, Curcumin and Bermuda grass. The optical absorption spectrum of the mono and hybrid dye extracts were studied by UV-Visible absorption spectrum. It shows the characteristic absorption peaks in visible region corresponds to the presence of natural pigments of anthocyanin, betacyanin and chlorophylls. Absorption spectrum of hybrid dyes reveals a wide absorption band in visible region with improved extinction co-efficient and it is favorable for increased light harvesting nature. The power conversion efficiency of DSSC devices were calculated using J-V curve and the maximum efficiency achieved in the present work is noted to be ~0.61% for Cactus-Bermuda co-sensitized DSSC.

  6. Improved quantum efficiency of highly efficient perovskite BaSnO₃-based dye-sensitized solar cells.

    PubMed

    Shin, Seong Sik; Kim, Ju Seong; Suk, Jae Ho; Lee, Kee Doo; Kim, Dong Wook; Park, Jong Hoon; Cho, In Sun; Hong, Kug Sun; Kim, Jin Young

    2013-02-26

    Ternary oxides are potential candidates as an electron-transporting material that can replace TiO₂ in dye-sensitized solar cells (DSSCs), as their electronic/optical properties can be easily controlled by manipulating the composition and/or by doping. Here, we report a new highly efficient DSSC using perovskite BaSnO₃ (BSO) nanoparticles. In addition, the effects of a TiCl₄ treatment on the physical, chemical, and photovoltaic properties of the BSO-based DSSCs are investigated. The TiCl₄ treatment was found to form an ultrathin TiO₂ layer on the BSO surface, the thickness of which increases with the treatment time. The formation of the TiO₂ shell layer improved the charge-collection efficiency by enhancing the charge transport and suppressing the charge recombination. It was also found that the TiCl₄ treatment significantly reduces the amount of surface OH species, resulting in reduced dye adsorption and reduced light-harvesting efficiency. The trade-off effect between the charge-collection and light-harvesting efficiencies resulted in the highest quantum efficiency (i.e., short-circuit photocurrent density), leading to the highest conversion efficiency of 5.5% after a TiCl₄ treatment of 3 min (cf. 4.5% for bare BSO). The conversion efficiency could be increased further to 6.2% by increasing the thickness of the BSO film, which is one of the highest efficiencies from non-TiO₂-based DSSCs. PMID:23316913

  7. Improved performance of polymer solar cells using PBDTT-F-TT:PC71BM blend film as active layer

    NASA Astrophysics Data System (ADS)

    Zang, Yue; Gao, Xiumin; Lu, Xinmiao; Xin, Qing; Lin, Jun; Zhao, Jufeng

    2016-07-01

    A detailed study of high-efficiency polymer solar cells (PSCs) based on a low bandgap polymer PBDTT-F-TT and PC71BM as the bulk heterojunction (BHJ) layer is carried out. By using 1,8-diiodooctane (DIO) as solvent additive to control the morphology of active layer and comparing different device architecture to optimize the optical field distribution, the power conversion efficiency (PCE) of the resulted devices can be reached as high as 9.34%. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of DIO and device geometry on photovoltaic performance. It was found that the addition of DIO can significantly improve the nanoscale morphology and increased electron mobility in the BHJ layer. The inverted device architecture was chosen because the results from optical modeling shows that it offers better optical field distribution and exciton generation profile. Based on these results, a low-temperature processed ZnO was finally introduced as an electron transport layer to facility the fabrication on flexible substrates and showed comparable performance with the device based on conventional ZnO interlayer prepared by sol-gel process.

  8. 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.

  9. Low-Reflectance Surfaces For Solar Cells

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Landis, Geoffrey A.; Fatemi, Navid; Jenkins, Phillip P.

    1994-01-01

    Improved method for increasing solar cell efficiency has potential application for space-based and terrestrial solar power systems and optoelectronic devices. Etched low-angle grooves help recover reflected light. Light reflected from v-grooved surface trapped in cover glass and adhesive by total internal reflection. Reflected light redirected onto surface, and greater fraction of incident light absorbed, producing more electrical energy in InP solar photovoltaic cell.

  10. Improved Charge-Collection Efficiency in PCDTBT:PC71BM-Based Solar Cells via CS2 Solvent Vapor Annealing

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Wu, Jiang; Fu, Ying-Ying; Meng, Bin; Xie, Zhi-Yuan; Guo, Shi-Jie

    2013-06-01

    Photo-generated charge collection is strongly correlated with the alignment and connectivity of the individual domains of donor and acceptor in bulk heterojunction polymer solar cells. It is found that CS2 vapor annealing on PCDTBT:PC71BM (1:4) blend effectively improves the hole-transport pathways of PCDTBT domains, which reduces accumulation of photo-generated charges and improves charge collection efficiency. The PCDTBT:PC71BM-based solar cells with the active layer subjected to CS2 vapor annealing demonstrate a high fill factor of 0.71-0.73 and a power conversion efficiency of 6.68%, about a 10% increase in comparison with the control cell.