Low cost thin film polycrystalline silicon solar cells. Final report, March 15, 1979-July 31, 1980

Technical Report · Tue Jul 01 04:00:00 EDT 1980

OSTI ID:5141518

The objective of this contract is to advance the thin film silicon solar cell technology with a view toward achieving photovoltaic conversion efficiencies greater than 10% at a cost of $100 to $300/kWe. The technical approaches consist of (1) the purification of metallurgical silicon by acid extraction and gettering techniques, (2) the preparation of metallurgical silicon substrates by the unidirectional solidification of the melt on graphite, (3) the deposition of a silicon p-n junction structure on metallurgical silicon substrates by the trichlorosilane process, and (4) the application of grid contacts and anti-reflection coatings. Major efforts were directed to the scale-up and optimization of all processing steps. The purification of metallurgical silicon by acid-extraction and phosphorus ntoxide treatment has been studied in detail. The minimum iron concentration obtainable is about 500 ppMa by the acid-extraction technique and is about 200 ppMa by the gettering technique. A standard procedure has been developed for the acid-extraction of metallurgical silicon, however, considerable difficulties have been encountered in the large-scale gettering process. Metallurgical silicon substrates have been prepared from the unidirectional solidification of the melt on graphite by the stationary and moving coil techniques. Many large area solar cells have been prepared from acid-extracted metallurgical silicon substrates by depositing the active region using the trichlorosilane process. The best cells (32 cm/sup 2/) have AM1 efficiencies of about 7.7%, and their photovoltaic properties have been characterized.

• Research Organization: Poly Solar, Inc., Garland, TX (USA)
• DOE Contract Number: AC03-79ET23048
• OSTI ID: 5141518
• Report Number(s): DOE/ET/23048-T1
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
CARBON
CARRIER DENSITY
CRYSTAL STRUCTURE
CRYSTALS
DATA
DATA FORMS
DEPOSITION
DIFFUSION LENGTH
DIRECT ENERGY CONVERTERS
DISSOLUTION
EFFICIENCY
ELECTRICAL PROPERTIES
ELEMENTS
EPITAXY
EQUIPMENT
FABRICATION
FILMS
GRAIN BOUNDARIES
GRAPHITE
GRAPHS
INFORMATION
LEACHING
MELTING
MICROSTRUCTURE
NONMETALS
PERFORMANCE
PHASE TRANSFORMATIONS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
POLYCRYSTALS
PURIFICATION
RECRYSTALLIZATION
SEMIMETALS
SEPARATION PROCESSES
SILICON
SILICON SOLAR CELLS
SOLAR CELLS
SOLAR EQUIPMENT
SOLIDIFICATION
SPECTRAL RESPONSE
SUBSTRATES
ZONE MELTING