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Title: Development of an improved high efficiency thin silicon solar cell. Quarterly report

Abstract

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.

Authors:
;
Publication Date:
Research Org.:
Solarex Corp., Rockville, MD (USA)
OSTI Identifier:
5666466
Alternate Identifier(s):
OSTI ID: 5666466
Report Number(s):
N-79-19459
DOE Contract Number:
NAS7-100; JPL-954883
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; SILICON SOLAR CELLS; RESEARCH PROGRAMS; DESIGN; EFFICIENCY; PERFORMANCE; SEMICONDUCTOR JUNCTIONS; DIRECT ENERGY CONVERTERS; EQUIPMENT; JUNCTIONS; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; SOLAR CELLS; SOLAR EQUIPMENT 140501* -- Solar Energy Conversion-- Photovoltaic Conversion

Citation Formats

Wrigley, C., and Storti, G. Development of an improved high efficiency thin silicon solar cell. Quarterly report. United States: N. p., 1978. Web.
Wrigley, C., & Storti, G. Development of an improved high efficiency thin silicon solar cell. Quarterly report. United States.
Wrigley, C., and Storti, G. Sat . "Development of an improved high efficiency thin silicon solar cell. Quarterly report". United States. doi:.
@article{osti_5666466,
title = {Development of an improved high efficiency thin silicon solar cell. Quarterly report},
author = {Wrigley, C. and Storti, G.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 1978},
month = {Sat Jul 01 00:00:00 EDT 1978}
}

Technical Report:
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  • Efforts were concerned with optimizing techniques for thinning silicon slices in NaOH etches, initial investigations of surface texturing, variation of furnace treatments to improve cell efficiency, initial efforts on optimization of gridline and cell sizes and Pilot Line fabrication of quantities of 2 cm x 2 cm 50 micrometer thick cells.
  • High efficiency cells (up to 14 AM0 at 25 C) were fabricated from 10 - 15 ohm-cm silicon by using screen printed aluminum paste as the alloy source for the production of back surface fields. Thick consistency pastes that have been cured prior to a short heat treatment at 850 C were most effective in achieving these efficiency levels.
  • One hundred thin (120 microns to 260 microns) silicon-aluminum solar cells were fabricated and tested. Silicon slices were prepared, into which an aluminum alloy was evaporated over a range of temperatures and times. Antireflection coatings of tantalum oxide were applied to the cells. Reflectance of the silicon-aluminum interfaces was correlated to alloy temperature (graphs are shown). Optical measurements of the rear surface-internal reflectance of the cells were performed using a Beckman spectrophotometer. An improved gridline pattern was evaluated and stability tests (thermal cycling tests) were performed. Results show that: (1) a high-index, high-transmittance antireflection coating was obtained; (2) the improvedmore » metallization of the cells gave a 60 percent rear surface-internal reflectance, and the cells displayed excellent fill factors and blue response of the spectrum; (3) an improved gridline pattern (5 micron linewidths compared to 13 micron linewidths) resulted in a 1.3 percent improvement in short circuit currents; and (4) the stability tests showed no change in cell properties. (GRA)« less
  • The ultimate high-efficiency silicon solar cell is a light-trapping thin-film silicon structure epitaxially grown on an oxide overcoated substrate such as silicon or gallium phosphide (GaP). In addition to high performance, this thin-base silicon device is more tolerant of radiation effects than a thick-base solar cell because this structure is less sensitive to reductions in minority-carrier diffusion length. The oxide overcoating layer, an integral part of this design, will serve as a dielectric back surface reflector leading to light trapping, and it will also eliminate dangling bonds in the overgrown silicon layer, effectively passivating the silicon-oxide interface and reducing back-surfacemore » recombination.« less