Research on High-Efficiency, Single-Junction, Monolithic, Thin-Film Amorphous Silicon Solar Cells: Phase 2, Semiannual Report, February 1, 1988-July 31, 1989.

摘要

This document describes efforts to improve the quality of candidate photovoltaic materials used in amorphous wide- and narrow-band-gap materials, namely, a-Si(sub 1-x)C(sub x) and a-Si(sub 1-x)Ge(sub x). Although these alloys show a decrease in mobility-lifetime product as the fraction of silicon decreases, their optical properties show marked differences. Microcrystalline p-layer films containing carbon were prepared to evaluate their importance for achieving high open-circuit voltages. Silicon-germanium cells were studied to optimize their performance in multijunction, stacked cell structures. The best cells fabricated from the silicon-germanium alloys yielded a conversion efficiency of 10.1% with a band gap of 1.55 eV. Several alloy-based stacked cells had conversion efficiencies of more than 10%: an a-SiC/a-SiGe cell yielded 10.5% and an a-SiC:H/a-Si:H structure yielded 10.2%. Stacked-junction cells showed far less susceptibility to light-induced degradation.