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U.S. Department of Energy
Office of Scientific and Technical Information

Thin film polycrystalline silicon solar cells. Second technical progress report, July 16, 1980-October 15, 1980

Technical Report ·
DOI:https://doi.org/10.2172/6809995· OSTI ID:6809995

The objectives of this contract are to fabricate large area thin film silicon solar cells with AM1 efficiency of 10% or greater with good reproducibility and good yield and to assess the feasibility of implementing this process for manufacturing solar cells at a cost of $300/kWe. Efforts have been directed to the purification of metallurgical silicon, the preparation and characterization of substrates and epitaxial silicon layers, and the fabrication and characterization of solar cells. The partial purification of metallurgical silicon by extraction with aqua regia has been further investigated in detail, and the resulting silicon was analyzed by the atomic absorption technique. The unidirectional solidification of aqua regia-extracted metallurgical silicon on graphite was used for the preparation of substrates, and the impurity distribution in the substrate was determined and compared with the impurity content in metallurgical silicon. The effects of heat treatment on the impurity distribution in the substrate and in the epitaxial layer have also been investigated. Large area (30 to 60 cm/sup 2/) solar cells have been prepared from aqua regia-extracted metallurgical silicon substrates by depositing a p-n junction structure using the thermal reduction of trichlorosilane containing appropriate dopants. The AM1 efficiencies are about 9% for cells of 30 to 35 cm/sup 2/ area. Larger area, 60 cm/sup 2/, thin film solar cells have been fabricated for the first time, and their AM1 efficiencies are slightly higher than 8%. The spectral response, minority carrier diffusion length, and I/sub sc/-V/sub oc/ relation in a number of solr cells have been measured.

Research Organization:
Poly Solar, Inc., Garland, TX (USA)
DOE Contract Number:
AC02-77CH00178
OSTI ID:
6809995
Report Number(s):
SERI/PR-9192-1-T2
Country of Publication:
United States
Language:
English