GAASP TOP SOLAR CELLS FOR INCREASED SOLAR CONVERSION EFFICIENCY

GAASP SOLAR CELLS PLACED ON TOP OF CONVENTIONAL SILICON SOLAR CELL ARRAYS CAN INCREASE THE ENERGY CONVERSION EFFICIENCY OF THE SYSTEM AS MUCH AS 100%. ASTROPOWER DIVISION OF ASTROSYSTEMS, INC. PROPOSES TO DEVELOP A HIGH BAND GAP TOP SOLAR CELL FOR ATTACHMENT TO CONVENTIONALS ILICON SOLAR CELLS. TRANSPARENT GAP SUBSTRATES WILL BE USED WITH EPITAXIALLY GROWN LAYERS OF GAASPH HAVING A BAND GAP OF 1.75 TO 2.1 EVAPPROPRIATE FOR MAXIMUM ABSORPTION FOR A TOP CELL WITH A SILICON BASE.THE GAASP SYSTEM HAS LESS MOISTURE AND OXIDATION SENSITIVITY AND IS MORE STABLE FOR ELECTRICAL CONTACTS THAN THE GAALAS ALTERNATIVE SYSTEM. AN ADDITIONAL BENEFIT FOR THE PROGRAM IS THAT THE ASTROPOWER DIVISION SENIOR PERSONNEL HAVE SUBSTANTIAL COMMERCIAL EXPERIENCE WITH THE PREPARATION OF GAASP AND GAP LIGHT EMITTING DIODES AND ARRAYS, AND ARE QUITE FAMILIAR WITH THE GAASP MATERIAL SYSTEMS. THE KEY TECHNICAL TASKS ARE LIQUID PHASE EPITAXY OF THE GAASP LAYERS, AND SYSTEMATIC SOLAR DESIGN AND FABRICATION. VARIOUS APPROACHES TO COMPOSITION GRADING TO MINIMIZE THE EFFECT OF LATTICE MISMATCH WILL BE EXPLORED EXPERIMENTALLY. LOSS MINIMIZATION WILL ALSO BE USED TO OPTIMIZE THE TANDEM DESIGN.