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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Progress and outlook of Sn–Pb mixed perovskite solar cells

Abstract Organic–inorganic hybrid perovskites have revolutionized solar cell research owing to their excellent material properties. Most previous research has been done on Pb-based perovskites. Recently, efforts to discover a Pb-free or Pb-less perovskite material with an ideal bandgap ranging 1.1–1.3 eV have led researchers to investigate Sn–Pb mixed perovskites. Sn–Pb mixed perovskites have a bandgap of ~ 1.25 eV, which is suitable for high-efficiency single-junction and perovskite/perovskite tandem solar cells. Moreover, the Pb content of Sn–Pb mixed perovskites is 50–60% lower than that of Pb-based perovskites, partially mitigating the Pb toxicity issue. However, incorporating Sn 2+ into the crystal structure also causes various drawbacks, such as inhomogeneous thin film morphologies, easy oxidation of Sn 2+ , and more vulnerable surface properties. Researchers have made substantial progress in addressing these challenges through improvements in compositional design, structural optimization, precursor design, and surface treatments. In this review, we provide a comprehensive overview of the progress in Sn–Pb mixed perovskite solar cells. Furthermore, we analyze the key variables and trends as well as provide an outlook for future directions in the research on Sn–Pb mixed perovskites. Graphical Abstract

14 SOLAR ENERGY↗
NASA NTRS1990

Results of the 1990 NASA/JPL balloon flight solar cell calibration program

The 1990 solar cell calibration balloon flight consisted of two flights, one on July 20, 1990 and the other on September 6, 1990. A malfunction occurred during the first flight, which resulted in a complete loss of data and a free fall of the payload from 120,000 ft. After the tracker was rebuilt, and several solar cell modules were replaced, the payload was reflown. The September flight was successful and met all the objectives of the program. Forty-six modules were carried to an altitude of 118,000 ft (36.0 km). Data telemetered from the modules was corrected to 28 C and to 1 a.u. The calibrated cells have been returned to the participants and can now be used as reference standards in simulator testing of cells and arrays.

Anspaugh, Bruce E.↗
NASA NTRS1993

Heteroepitaxial InP, and ultrathin, directly glassed, GaAs 3-5 solar cells

The commercial application of Indium Phosphide solar cells in practical space missions is crucially dependent upon achieving a major cost reduction which could be offered by heteroepitaxy on cheaper, more rugged substrates. Furthermore, significant mass reduction, compatibility with mechanically stacked multijunction cells, and elimination of the current loss through glue discoloration, is possible in III-V solar cells by the development of ultrathin, directly glassed cells. The progress of a UK collaborative program to develop high efficiency, homojunction InP solar cells, grown by MOCVD on Si substrates, is described. Results of homoepitaxial cells (is greater than 17 percent 1 Sun AM0) are presented, together with progress in achieving low dislocation density heteroepitaxy. Also, progress in a UK program to develop ultrathin directly-glassed GaAs cells is described. Ultrathin (5 micron) GaAs cells, with 1 Sun AM0 efficiencies up to 19.1 percent, are presented, together with progress in achieving a direct (adhesive-less) bond between the cell and coverglass. Consequential development to, for example, cell grids, are also discussed.

Hardingham, C. M.↗
NASA NTRS1978

Process for utilizing low-cost graphite substrates for polycrystalline solar cells

Low cost polycrystalline silicon solar cells supported on substrates were prepared by depositing successive layers of polycrystalline silicon containing appropriate dopants over supporting substrates of a member selected from the group consisting of metallurgical grade polycrystalline silicon, graphite and steel coated with a diffusion barrier of silica, borosilicate, phosphosilicate, or mixtures thereof such that p-n junction devices were formed which effectively convert solar energy to electrical energy. To improve the conversion efficiency of the polycrystalline silicon solar cells, the crystallite size in the silicon was substantially increased by melting and solidifying a base layer of polycrystalline silicon before depositing the layers which form the p-n junction.

Chu, T. L.↗
NASA NTRS1992

Three-dimensional numerical modeling of indium phosphide Point-Contact Solar Cells

The Point-Contact Solar Cell (PCSC) geometry has proven very effective for silicon cells. To date, it has not been implemented in III-V materials. In addition, modeling such a geometry is very difficult because of its three-dimensional nature. We have developed a three-dimensional finite element modeling code (FIESTA ROC). In this paper, we present results from a three-dimensional modeling study of InP point-contact solar cells.

Clark, Ralph O.↗
NASA NTRS1978

Environmental qualification testing of terrestrial solar cell modules

The placement of solar cell modules in various climates and locations throughout the world results in different degrees and combinations of environmental stresses. Coupled with a design lifetime goal of 20 years, early detection and correction of module design deficiencies can result in significantly better long-term economics. This paper describes an environmental test research program for developing qualification requirements and procedures for flat-plate solar cell modules. A multiple iterative approach for establishing and evaluating test requirements is discussed as well as the rationale for the selection of levels and durations for the current qualification tests. The status of study efforts involving optical surface soiling, encapsulation delamination, and voltage bias-humidity testing is reviewed.

Hoffman, A. R.↗
DOE OSTI2022

Shingled solar cells overlapping along non-linear edges

Solar devices and methods for producing solar devices are disclosed. In some examples, a solar device includes solar cells arranged in a shingled manner such that adjacent long edges of adjacent ones of the solar cells overlap. The adjacent long edges have a non-linear shape that has protruding portions. The solar device includes contact pads arranged in the protruding portions of the adjacent long edges such that the contact pads of the adjacent ones of the solar cells are electrically connected.

Caswell, Nathaniel Alexis↗
NASA NTRS1977

Measurement of material parameters that limit the open-circuit voltage in P-N-junction silicon solar cells

The greatest gains in solar energy conversion efficiency of p-n-junction silicon solar cells come from increasing the open-circuit voltage V sub OC; it is important to understand and characterize the material parameters that limit the V sub OC. Strong experimental evidence exists to support the assertion that either an anomalously large minority carrier charge storage or an anomalously small minority carrier lifetime in the quasi-neutral emitter region limits the open circuit voltage. A method is presented for measuring charge storage and effective lifetime. Static and transient measurements are analyzed using physical models of the solar cell characteristics. This analysis yields the emitter charge storage and life-time, which then can be related to the various physical mechanisms, such as energy band gap shrinkage, that have been proposed earlier as responsible for limiting V sub OC.

Lindholm, F. A.↗
DOE OSTI2020

A review of Sb 2 Se 3 photovoltaic absorber materials and thin-film solar cells

Energy generated from environmentally friendly, cost-effective solar cells is a key aspect for developing a clean renewable-energy economy. Non-toxic and Earth-abundant materials with high absorption coefficient (>10 5 cm -1 ) and optimal bandgap (1-1.5 eV) have received great attention as photovoltaic (PV) absorber layers during the last few decades. Among them, antimony selenide (Sb 2 Se 3 ) has been a promising PV absorber, with steadily increasing power-conversion efficiency (PCE) compared to other emerging compounds. Very recent studies showed that high-quality ZnO:Al/ZnO/CdS/TiO 2 /Sb 2 Se 3 /MoSe 2 /Mo devices with PCE of 9.2% can be fabricated using cost-effective novel compounds. Considering these recent advances, this article provides an overview of the material properties of Sb2Se3 thin films and the recent progress made with Sb 2 Se 3 -based solar cells. Furthermore, analysis of Sb 2 Se 3 -based thin-film solar cells has also shown that the devices have relatively good light management due to their suitable bandgap and high absorption coefficient, whereas carrier management, i.e. collection efficiency of photo-generated carriers, needs significant improvement. Overall, this study provides background knowledge on material properties and device performance and suggests main research directions to overcome the limiting factors of solar cell performance.

14 SOLAR ENERGY↗
DOE OSTI2021

Structural Stability of Tin-Lead Halide Perovskite Solar Cells

One of the key features that makes halide perovskite solar cells such an attractive and intensely researched photovoltaic (PV) technology, is the tunability of the bandgap of these halide perovskite materials [1], [2]. Shortly after it was established that the bandgap could be increased to 1.7-1.8 eV, investigations into the application for silicon based tandem solar cells launched. Within a few years, conversion efficiencies of up to 28 % have been reported [3]. Concurrently, the interest in commercial application of this technology emerged and have rapidly increased. Whereas there are advantages to piggy backing on an established PV technology such as silicon, efforts to develop all-perovskite tandem solar cells are of considerable interest. Partly substituting the metal cation in the ABX3 perovskite enables the low bandgap absorbers required for an all-perovskite tandem solar cell. One common approach is to partially substitute the lead with tin, however these materials often suffered from poor stability. Therefore the development of an efficient, stable mixed tin-lead perovskite is key to enabling all-perovskite tandem solar cells.

degradation↗
DOE OSTI2025

High‐Speed Slot‐Die Coating with Donor‐Priority Rapid Aggregation Kinetics for Improved Morphology and Efficiency in Ecofriendly Organic Solar Cells

Abstract Solution‐processable organic solar cells (OSCs) represent a promising renewable photovoltaic technology with significant potential for eco‐compatible production. While high power conversion efficiencies (PCEs) have been achieved in OSCs, scaling this technology for high‐throughput manufacturing remains challenging. Key reason lies in the lack of efficient control strategies for the complex and long‐duration morphology evolution during high‐speed coating process with ecofriendly solvents. Here, a donor‐priority rapid aggregation process (DP‐RAP) scheme is proposed to solve this issue by adjusting the aggregation kinetics of donor and acceptor components. DP‐RAP enables blends with a nanoscale fiber network structure and favorable crystallinity, which contributes to balanced carrier transport and reduced recombination losses. As a result, the PCE is improved from 14.3% (reference) to 17.4% (DP‐RAP) for ultra‐high speed coated PM6:BTP‐eC9 devices in atmosphere, which is one of the highest values for non‐halogenated solvent‐processed solar cells at coating speeds of 500 mm s −1 . Moreover, the DP‐RAP based devices remain a stable PCE of approximately 17.4% across a broad range of coating speeds (20–500 mm s −1 ), illustrating its tolerance to the varied manufacturing conditions. This work highlights a promising avenue for the high‐speed, ecofriendly production of efficient OSCs, pushing the boundaries of practical manufacturing in renewable energy technologies.

Chemistry↗
NASA NTRS1975

Cadmium sulfide solar cells

Development, fabrication and applications of CdS solar cells are reviewed in detail. The suitability of CdS cells for large solar panels and microcircuitry, and their low cost, are emphasized. Developments are reviewed by manufacturer-developer. Vapor phase deposition of thin-film solar cells, doping and co-evaporation, sputtering, chemical spray, and sintered layers are reviewed, in addition to spray deposition, monograin layer structures, and silk screening. Formation of junctions by electroplating, evaporation, brushing, CuCl dip, and chemiplating are discussed, along with counterelectrode fabrication, VPD film structures, the Cu2S barrier layer, and various photovoltaic effects (contact photovoltage, light intensity variation, optical enhancement), and various other CdS topics.

Stanley, A. G.↗
NASA NTRS1984

Radiation effects in silicon and gallium arsenide solar cells using isotropic and normally incident radiation

Several types of silicon and gallium arsenide solar cells were irradiated with protons with energies between 50 keV and 10 MeV at both normal and isotropic incidence. Damage coefficients for maximum power relative to 10 MeV were derived for these cells for both cases of omni-directional and normal incidence. The damage coefficients for the silicon cells were found to be somewhat lower than those quoted in the Solar Cell Radiation Handbook. These values were used to compute omni-directional damage coefficients suitable for solar cells protected by coverglasses of practical thickness, which in turn were used to compute solar cell degradation in two proton-dominated orbits. In spite of the difference in the low energy proton damage coefficients, the difference between the handbook prediction and the prediction using the newly derived values was negligible. Damage coefficients for GaAs solar cells for short circuit current, open circuit voltage, and maximum power were also computed relative to 10 MeV protons. They were used to predict cell degradation in the same two orbits and in a 5600 nmi orbit. Results show the performance of the GaAs solar cells in these orbits to be superior to that of the Si cells.

Anspaugh, B. E.↗
NASA NTRS1984

Radiation effects in silicon and gallium arsenide solar cells using isotropic and normally incident radiation

Several types of silicon and gallium arsenide solar cells were irradiated with protons with energies between 50 keV and 10 MeV at both normal and isotropic incidence. Damage coefficients for maximum power relative to 10 MeV were derived for these cells for both cases of omni-directional and normal incidence. The damage coefficients for the silicon cells were found to be somewhat lower than those quoted in the Solar Cell Radiation Handbook. These values were used to compute omni-directional damage coefficients suitable for solar cells protected by coverglasses of practical thickness, which in turn were used to compute solar cell degradation in two proton-dominated orbits. In spite of the difference in the low energy proton damage coefficients, the difference between the handbook prediction and the prediction using the newly derived values was negligible. Damage coefficients for GaAs solar cells for short circuit current, open circuit voltage, and maximum power were also computed relative to 10 MeV protons. They were used to predict cell degradation in the same two orbits and in a 5600 nmi orbit. Results show the performance of the GaAs solar cells in these orbits to be superior to that of the Si cells.

Anspaugh, B. E.↗
NASA NTRS1994

High quality InP-on-Si for solar cell applications

InP on Si solar cells combine the low-cost and high-strength of Si with the high efficiency and radiation tolerance of InP. The main obstacle in the growth of single crystal InP-on-Si is the high residual strain and high dislocation density of the heteroepitaxial InP films. The dislocations result from the large differences in lattice constant and thermal expansion mismatch of InP and Si. Adjusting the size and geometry of the growth area is one possible method of addressing this problem. In this work, we conducted a material quality study of liquid phase epitaxy overgrowth layers on selective area InP grown by a proprietary vapor phase epitaxy technique on Si. The relationship between growth area and dislocation density was quantified using etch pit density measurements. Material quality of the InP on Si improved both with reduced growth area and increased aspect ratio (length/width) of the selective area. Areas with etch pit density as low as 1.6 x 10(exp 4) sq cm were obtained. Assuming dislocation density is an order of magnitude greater than etch pit density, solar cells made with this material could achieve the maximum theoretical efficiency of 23% at AMO. Etch pit density dependence on the orientation of the selective areas on the substrate was also studied.

Shellenbarger, Zane A.↗
NASA NTRS1981

Electrostatic bonding of thin (cycle sine 3 mil) 7070 cover glass to Ta2O5 AR-coated thin (cycle sine 2 mil) silicon wafers and solar cells

Electrostatic bonding of thin cover glass to thin solar cells was researched. Silicon solar cells, wafers, and Corning 7070 glass of from about 0.002" to about 0.003" in thickness were used in the investigation to establish optimum parameters for producing mechanically acceptable bonds while minimizing thermal stresses and resultant solar cell electrical parameter degradation.

Egelkrout, D. W.↗
DOE OSTI2023

Screen printable copper pastes for silicon solar cells

The current work demonstrates the successful metallization of a PERC silicon solar cell with screen-printable copper (Cu) paste that is sintered at elevated temperature in air atmosphere. The existing state of the art in Silicon (Si) solar cell metallization is silver (Ag) paste; Cu cost is 1/100th the cost of Ag and has a comparable conductivity. However, Cu undergoes rapid oxidation at elevated temperatures and the high diffusion of Cu into Si restricts its usage in the metallization of silicon solar cells. In this paper, a Cu paste containing a proprietary mixture of antioxidant additives and diffusion inhibitors was used to make front gridlines on PERC cells. The Cu-printed cells were fired in an IR belt furnace with a peak temperature of 576°C in air atmosphere. The solar cells discussed here reached an efficiency of 19%, which is 88% of the efficiency measured for a commercial Ag-printed cell. The working devices were further characterized using STEM, EDX, ToF-SIMS and long-term suns-V oc studies demonstrating an absence of Cu diffusion. Furthermore, thermally stressing the Cu-printed solar cells yielded a reduction of less than 1.9% of the initial pseudo fill factor (pFF) after 1000 hours at 200°C. Here, the shunt resistance of cells monitored over 3 years remained within 2.5% of its initial value, which demonstrates the effectiveness of the Cu diffusion barrier.

14 SOLAR ENERGY↗