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At least 325 records · Page 18

Metallization of conductive wires for solar cells

Methods of fabricating a solar cell, and system for electrically coupling solar cells, are described. In an example, the methods for fabricating a solar cell can include placing conductive wires in a wire guide, where conductive wires are placed over a first semiconductor substrate having first doped regions and second doped regions. The method can include aligning the conductive wires over the first and second doped regions, where the wire guide aligns the conductive wires substantially parallel to the first and second doped regions. The method can include bonding the conductive wires to the first and second doped regions. The bonding can include applying a mechanical force to the semiconductor substrate via a roller or bonding head of the wire guide, where the wire guide inhibits lateral movement of the conductive wires during the bonding.

Sewell, Richard Hamilton↗

GaAs Solar Cell Radiation Handbook

History of GaAs solar cell development is provided. Photovoltaic equations are described along with instrumentation techniques for measuring solar cells. Radiation effects in solar cells, electrical performance, and spacecraft flight data for solar cells are discussed. The space radiation environment and solar array degradation calculations are addressed.

Anspaugh, B. E.↗

Residual Stress Limits Gridline Bridging in Cracked Solar Cells

Cracks in solar cells can be generated in various ways, but this does not mean immediate power loss. Previous studies showed that gridlines bridge cracked silicon cells, and the bridging behavior decreases during the contact and separation of gridlines within bare cells. In this study, we investigate bridging behavior in laminated monocrystalline cells. We characterize the behavior with Weibull analysis of critical crack opening distance (COD), at which the gridline is completely separated. The Weibull analysis of the laminated cell shows a good agreement with bare cells at the first cycle. However, we observe different behavior during cyclic bending. Bare cells show gradual decay of critical COD, while laminated cells show instant decay and plateau. We hypothesize that the difference is due to residual stress, squeezing gridlines, and causing plastic deformation. This is justified by the correlation between critical COD and gridline morphology. In the presentation, we shall present a Weibull analysis of the cyclic bending of a laminated cell with a reduced residual stress effect.

bending↗

Dot junction solar cells

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

Daud, T.↗

Comprehensive Silicon-Solar-Cell Program

Comprehensive Silicon Solar Cell Computer Modeling (SICELL) program simulates silicon solar cell. Predicts device parameters as efficiency, voltage-vs.-current characteristic fill factor, and temperature coefficients of parameters. Technique used similar to numerical-integration methods, but commonality described by use of mesh-point field. Validation studies show accuracies of simulations range from 0.08 percent to 3.6 percent for 27 experimental data points over temperature range of 300K to 421K. Results obtained by use of 10 mesh points in n- and p-type regions and for two iterations. SICELL runs interactively on VAX computer under VMS and written in VAX/VMS FORTRAN 77.

Lamorte, Michael F.↗

Carbon nanomaterials–polymer composites for perovskite solar cells: preparation, properties and applications

Perovskite solar cells (PSCs) are a rising star in the photovoltaic industry, which achieved an enormous breakthrough in terms of efficiency from an initial 3.8% in 2009 to 25.7% in 2021. Here, the major challenge to bring perovskite solar cells commercially available is the poor long-term device stability. The defects in perovskite and energy loss originating from charge recombination limit the efficiency of perovskite solar cells. Carbon–polymer composites, which feature superb electrical conductivity, outstanding carrier mobility, remarkable flexibility and superior heat and moisture stability, have attracted considerable attention to tackle these issues. With their multifunctional properties, carbon–polymer composites can play various roles in almost every component in the perovskite solar cell architecture. In this review article, recent progress concerning the utilization of carbon–polymer composites in different components in PSCs (i.e., perovskite additives, electrodes, encapsulation layers and charge transport layers) is comprehensively overviewed. Then, future research directions and opportunities toward high-performance perovskite solar cells utilizing carbon–polymer composites are presented.

36 MATERIALS SCIENCE↗

Development of a shingle-type solar cell module

The development of a solar cell module, which is suitable for use in place of shingles on the sloping roofs of residental or commercial buildings, is reported. The design consists of nineteen series-connected 53 mm diameter solar cells arranged in a closely packed hexagon configuration. The shingle solar cell module consists of two basic functional parts: an exposed rigid portion which contains the solar cell assembly, and a semi-flexible portion which is overlapped by the higher courses of the roof installation. Consideration is given to the semi-flexible substrate configuration and solar cell and module-to-module interconnectors. The results of an electrical performance analysis are given and it is noted that high specific power output can be attributed to the efficient packing of the circular cells within the hexagon shape. The shingle should function for at least 15 years, with a specific power output of 98 W/sq w.

Shepard, N. F., Jr.↗

GaAsP on GaP top solar cells

GaAsP on GaP top solar cells as an attachment to silicon bottom solar cells are being developed. The GaAsP on GaP system offers several advantages for this top solar cell. The most important is that the gallium phosphide substrate provides a rugged, transparent mechanical substrate which does not have to be removed or thinned during processing. Additional advantages are that: (1) gallium phosphide is more oxidation resistant than the III-V aluminum compounds, (2) a range of energy band gaps higher than 1.75 eV is readily available for system efficiency optimization, (3) reliable ohmic contact technology is available from the light-emitting diode industry, and (4) the system readily lends itself to graded band gap structures for additional increases in efficiency.

Mcneely, J. B.↗

Flexible transparent conducting electrodes unexpectedly influence MAPbI 3 film morphology and perovskite solar cell performance

Fabricating perovskite solar cells (PSCs) on plastic substrates will enable cost-effective manufacturing of lightweight and portable energy systems. Here, we study the influence of flexible transparent conductive electrodes (TCEs) on the methylammonium lead iodide (MAPbI3) film morphology and PSC performance. Three types of TCEs on polyethylene terephthalate (PET) are compared: a custom-made AgNWs/indium zinc oxide hybrid TCE and two commercial substrates with indium tin oxide (ITO) or metal/insulator/metal (MIM) as the TCE. Using the same p-i-n architecture and hole transport layer (HTL), we find that PSCs fabricated on the hybrid TCE show better performance and stability compared to those made on commercial TCEs. The PSC performance enhancement is attributed to the superior structural and optical properties of MAPbI3 film deposited on the hybrid TCE, which is explained by the surface energy difference of the HTL. While it is anticipated that solar cell performance can be affected by TCEs’ transmittance and sheet resistance as they determine light absorption and carrier transport, respectively, our finding of TCE influencing the morphology and crystallinity of MAPbI3 film, and hence PSC performance, is unexpected.

14 SOLAR ENERGY↗

Co‐Doping Approach for Enhanced Electron Extraction to TiO 2 for Stable Inorganic Perovskite Solar Cells

Inorganic perovskite CsPbI 3 solar cells hold great potential for improving the operational stability of perovskite photovoltaics. However, electron extraction is limited by the low conductivity of TiO 2 , representing a bottleneck for achieving stable performance. In this study, a co‐doping strategy for TiO 2 using Nb(V) and Sn(IV), which reduces the material's work function by 80 meV compared to Nb(V) mono‐doped TiO 2 , is introduced. To gain fundamental understanding of the processes at the interfaces between the perovskite and charge‐selective layer, transient surface photovoltage measurements are applied, revealing the beneficial effect of the energetic and structural modification on electron extraction across the CsPbI 3 /TiO 2 interface. Using 2D drift‐diffusion simulations, it is found that co‐doping reduces the interface hole recombination velocity by two orders of magnitude, increasing the concentration of extracted electrons by 20%. When integrated into n–i–p solar cells, co‐doped TiO 2 enhances the projected T S80 lifetimes under continuous AM1.5G illumination by a factor of 25 compared to mono‐doped TiO 2 . This study provides fundamental insights into interfacial charge extraction and its correlation with operational stability of perovskite solar cells, offering potential applications for other charge‐selective contacts.

14 SOLAR ENERGY↗

Irradiation Experiments on High Efficiency Nanowire Solar Cells Including Tilted Incidence Angle

Nanowire based solar cells have promising potential to become the next generation of space solar cells. In this study we corroborate their high radiation tolerance by irradiating high efficiency GaAs (efficiency > 15 %) nanowire solar cells with 1 MeV electrons at a fluence of 10 16 e - /cm 2 . Additionally, we theoretically show that the damage in nanowire solar cells is expected to be slightly dependent on the incidence angle and the geometry of the nanowire array. However, experimentally, two sets of GaAs nanowire solar cells have been irradiated with 1 MeV electrons at normal incidence and with a 25° tilted angle exhibiting a similar degradation.

high specific power↗

Practical anti-reflection coating for metal semiconductor solar cells

The metal-semiconductor solar cell is a possible candidate for converting solar to electrical energy for terrestrial application. A method is given for obtaining optical parameters of practical antireflection coatings for the metal-semiconductor solar cell. This method utilizes the measured refractive index obtained from ellipsometry since the surface to be AR coated has a multilayer structure. Both the experimental results and theoretical calculation of optical parameters for Ta2O5 antireflection coatings on Au-GaAs and Au-GaAs(0.78)P(0.22) solar cells are presented for comparison.

Yeh, Y.-C. M.↗

Practical antireflection coatings for metal-semiconductor solar cells

The metal-semiconductor solar cell is a potential candidate for converting solar energy to electrical energy for space and terrestrial application. In this paper, a method for obtaining parameters of practical antireflection (AR) coatings for the metal-semiconductor solar cells is given. This method utilizes the measured equivalent index of refraction obtained from ellipsometry, since the surface to be AR coated has a multilayer structure. Both the experimental results and theoretical calculations of optical parameters for Ta2O5 AR coatings on Au-GaAs and Au-GaAs(0.78)P(0.22) solar cells are presented for comparison.

Yeh, Y. C. M.↗

Laser process and corresponding structures for forming contact holes of solar cells

Contact holes of solar cells are formed by laser ablation to accommodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thicknesses.

14 SOLAR ENERGY↗

Process and structures for fabrication of solar cells

Contact holes of solar cells are formed by laser ablation to accommodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thicknesses.

14 SOLAR ENERGY↗

Thin n-i-p radiation-resistant solar cell feasibility study

Silicon solar cells were fabricated to verify the predictions that: (1) thin n(+)pp(+) cells can provide high values of open circuit voltage even when high resistivity base material ( 1000 omega-cm) is used; (2) cells with good p(+) back contacts will display an increase in open circuit voltage with decreasing cell thickness; and (3) high quality, thin, high resistivity, solar cells can be made using processing compatible with conventional practice. Analysis of I-V and spectral response measurements of these cells confirmed theoretical predictions and thereby pointed to voltages beyond the near 600 mV obtained in this study.

Allison, J. F.↗

GaAs solar cells for space applications

GaAs solar cells offer substantial advantages for space photovoltaic power over Si solar cells in the areas of efficiency, elevated temperature operation, and radiation damage stability. A mission cost comparison is made for GaAs and Si solar cells. For Si cell arrays, the total mission cost is found to be a minimum for a solar concentration of 2.9. For GaAs, modes of operation and construction are investigated. Modes having lower mission costs than the minimum Si mission cost are defined. These include higher concentrations, lightweight cells, and simultaneous power generation and annealing. The technological progress necessary for GaAs to operate in these modes is identified.

Conway, E. J.↗