Advancement of the state-of-the-art in the production of drift field solar cells Final project report, 23 Jun. 1965 - 23 Jan. 1966
Drift-field solar cell fabrication with space environment radiation resistance capabilities
RADIATION RESISTANCE↗
SEARCH · Engineering Papers
Results for “Cell Fabrication”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Safety considerations of lithium-thionyl chloride cells
The use of spirally wound lithium-thionyl chloride (Li-SOCl2) cells is currently limited because of their hazardous behavior. Safety hazards have ranged from mild venting of toxic materials to violent explosions and fires. These incidents may be related to both user- and manufacturer-induced causes. Many explanations have been offered to explain the unsafe behavior of the cells under operating and abuse conditions. Explanations fall into two categories: (1) thermal mechanisms, and (2) chemical mechanisms. However, it is quite difficult to separate the two. Both may be responsible for cell venting or explosion. Some safety problems encountered with these cells also may be due to design deficiencies and ineffective quality control during cell fabrication. A well-coordinated basic and applied research program is needed to develop safe Li-SOCl2 cells. Recommendations include: (1) learnig more about Li-SOL2 cell chemistry; (2) modeling cell and battery behavior; (3) optimizing cell design for safety and performance, (4) implementing quality control procedures; and (5) educating users.
Subbarao, Surampudi↗
GaAs solar cells for laser power beaming
Efforts to develop GaAs solar cells for coupling to laser beams in the wavelength range of 800 to 840 nm are described. This work was motivated primarily by interests in space-tp-space power beaming applications. In particular, the Battelle Pacific Northwest Laboratories is conducting studies of the utilization of power beaming for several future space missions. Modeling calculations of GaAs cell performance were carried out using PC-1D to determine an appropriate design for a p/n cell structure. Epitaxial wafers were grown by MOCVD and cells fabricated at WSU Tri-Cities. Under simulated conditions, an efficiency of 53 percent was achieved for a cell coupled to 806 nm light at 400 mW/sq cm.
Olsen, Larry C.↗
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↗
Performance Trade-Offs for MBG Using Different Bandgap Pairs
Present GAInP2/GAAs cell grown on Ge (or GaAs) substrates have demonstrates high efficiency, However, the individual bandgaps (1.85 eV, 1.42 eV respectively) are not the optimum match to convert the AM0 spectrum efficiently, although by reducing the thickness of the GaInP2 cell, good efficiencies have been achieved. Within the III-V alloys, modeling shows that several dual junction cells, comprising different bandgap pairs, could give higher efficiency. This paper outlines the modeling used, the bandgap pairs selected, and projections for the AM0 efficiency assuming that the effects of lattice mismatch associated with the bandgap can be reduced. We also present preliminary data on I-V performance for the selected top and bottom cells and for some full cascade cells. We have included some characterization results to check the bandgaps and lattice strain, to check how closely the fabricated cells conform to the model,
Iles, P. A.↗
Improved reproducibility of metal halide perovskite solar cells via automated gas quenching
Achieving reproducible perovskite solar cell fabrication is crucial for making it a scalable technology. We demonstrate an automated gas quenching system to improve perovskite solar cell reproducibility at the lab-scale. We use in situ photoluminescence to monitor the perovskite film formation as a function of the atmosphere in the glove box and find that antisolvent quenching is more sensitive to lingering precursor solvents than the gas quenching method. We observe a better reproducibility with gas quenching than with antisolvent quenching because it maintains a more consistent atmosphere in the glove box. The automated gas quenching process leads to high performing devices that are reproducible both batch to batch and researcher to researcher. The insights into gas quenching film formation as a function of solvent atmosphere and quench velocity will help inform future studies on large scale fabrication systems.
14 SOLAR ENERGY↗
Research and development study on improvement of advanced radiation resistant modularization techniques Final report, 15 May - 30 Nov. 1964
Radiation-resistant modularization techniques for development of wrap-around solar cell - fabrication of modules on thin dielectric material containing printed circuit connections
MODULE↗
Silicon materials task of the low cost solar array project, part 2
Purity requirements for solar cell grade silicon material was developed and defined by evaluating the effects of specific impurities and impurity levels on the performance of silicon solar cells. Also, data was generated forming the basis for cost-tradeoff analyses of silicon solar cell material. Growth, evaluation, solar cell fabrication and testing was completed for the baseline boron-doped Czochralski material. Measurements indicate Cn and Mn seriously degrade cell performance, while neither Ni nor Cu produce any serious reduction in cell efficiency.
Hopkins, R. H.↗
High efficiency thin-film GaAs solar cells
Several oxidation techniques are discussed which have been found to increase the open circuit (V sub oc) of metal-GaAs Schottky barrier solar cells, the oxide chemistry, attempts to measure surface state parameters, the evolving characteristics of the solar cell as background contamination (has been decreased, but not eliminated), results of focused Nd/YAG laser beam recrystallization of Ge films evaporated onto tungsten, and studies of AMOS solar cells fabricated on sliced polycrystalline GaAs wafers. Also discussed are projected materials availability and costs for GaAs thin-film solar cells.
Stirn, R. J.↗
Electro-Optical Effects in Thin Organic Films
Meta-nitroaniline (mNA) and 2-cyclo-octylamino-5-nitropyridine (COANP) single crystals were grown between two transparent fused quartz plates on which indium-tin-oxide layers were deposited. Both linear and quadratic electro-optic effects of the crystals were examined by an ac modulation method. The figures of merit for mNA and COANP are estimated to be 3.2(10-12 m/V and 4.2(10-12 m/V, respectively. It was found that the crystals were under good protection of the cells and the figure of merits of the crystals did not decrease with time. It is believed that the method adopted in the paper is applicable to electro-optic cell fabrication with other compounds if those crystals growth from melt is feasible. It is suggested that the electro-optic cells have potential fortune because of their durability and relative easy manipulation processes of crystal growth.
Leyderman, Alexander↗
Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project
The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC.
Grung, B. L.↗
Investigation of the stability and 1.0 MeV proton radiation resistance of commercially produced hydrogenated amorphous silicon alloy solar cells
The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys is reported. A number of different device structures were irradiated with 1.0 MeV protons. The cells were annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters or fluences below 1(exp 14) cm(exp -2); fluences above 1(exp 14) cm(exp -2) require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed in dark I-V measurements. The current mechanisms were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.
Lord, Kenneth R., II↗
Radiation Resistance Studies of Amorphous Silicon Alloy Photovoltaic Materials
The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys was investigated. A number of different device structures were irradiated with 1.0 MeV protons. The cells were insensitive to proton fluences below 1E12 sq cm. The parameters of the irradiated cells were restored with annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters for fluences below lE14 sq cm require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed in dark I-V measurements. The current mechanisms were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.
Woodyard, James R.↗
Investigation of the Stability and 1.0 MeV Proton Radiation Resistance of Commercially Produced Hydrogenated Amorphous Silicon Alloy Solar Cells
The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys is reported. A number of different device structures were irradiated with 1.0 MeV protons. The cells were insensitive to proton fluences below 1E12 sq cm. The parameters of the irradiated cells were restored with annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters for fluences below 1E14 sq cm fluences above 1E14 sq cm require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed In dark I-V measurements. The current mechanism were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.
Lord, Kenneth R., II↗
Impact of Electrode Thickness and Temperature on the Rate Capability of Li 4 Ti 5 O 12 /LiMn 2 O 4 Cells
Growing demand for stationary energy storage systems requires the development of low cost, long cycle life, safe batteries. Lithium-ion batteries (LiBs) utilizing Li 4 Ti 5 O 12 /LiMn 2 O 4 (LMO) cathode are promising candidates providing critical-material-free chemistry, high power capability, and long lifespan. However, their low energy density is a major drawback. In this work, we evaluate the rate performance of LTO/LMO cells fabricated with electrode loadings from 1.7 to 4.2 mAh cm -2 toward the development of high energy density and low cost LTO/LMO cells. The operating temperature is varied from 30 °C to 55 °C to evaluate the impact of electrode thickness vs temperature limitations on the electrode utilization. In addition, Newman modeling is performed to provide detailed understandings of the cell performance. Combining experimental and simulated results, we show the rate capability of the thicker electrodes is limited by the electrolyte transport. When the cells are discharged by applying pulsed current, Li + ion depletion is mitigated and the discharge capacity increases. Thus, high energy density LTO/LMO cells for BTMS applications can operate more efficiently when intermittent rest is applied. Finally, overcoming electrolyte transport limitations will be the key to enabling the development of high energy density LTO/LMO cells using thick electrodes.
25 ENERGY STORAGE↗
Characterization and modelling of open tube diffused n+p bulk InP solar cells
The authors describe the photovoltaic characteristics of an n+p junction solar cell fabricated on bulk InP by an open-tube-diffusion technique. Analysis of the forward characteristics shows that the forward current is dominated by recombination in the quasineutral regions, indicating that the fabrication technique produces a clean junction. Spectral response measurements are analyzed and more realistic boundary conditions are used to model the solar cell to determine important material and device parameters.
Bothra, S.↗
Strip cell test and evaluation program
The performance characteristics of alkaline fuel cells to be used for space power systems were tested. Endurance tests were conducted on the cells during energy conversion operations. A feature of the cells fabricated and tested was the capability to evaporate the product water formed during the energy conversion reaction directly to space vacuum. A fuel cell powerplant incorporating these cells does not require a condenser and a hydrogen recirculating pump water separator to remove the product water. This simplified the fuel cell powerplant system, reduced the systems weight, and reduced the systems parasite power.
Gitlow, B.↗
The effects of copper and titanium on silicon solar cells
Copper-doped N/P silicon solar cells fabricated from the Czochralski grown single-crystal wafers were found to have good electrical characteristics, but the titanium-doped N/P silicon solar cells has considerably lower conversion efficiency. However, in the copper/titanium-doped solar cells, copper seems to mitigate the unfavorable effects of titanium. To explain this behavior, microstructural tests were performed on silicon wafers and solar cells doped with copper, titanium and copper/titanium. Dark forward and reverse I-V measurements were performed on the solar cells to correlate the microstructural defects with the p-n junction properties. It was found that copper precipitates were formed in the copper-doped and copper/titanium-doped wafers and cells. There was a significant voltage drop in the dark reverse I-V measurements of the titanium solar cells. Also, there were some electronically active defects in the depletion region of some titanium-doped cells. Reasons that lead to the above results are given in detail.
Salama, A. M.↗