15.1-PERCENT HIGHLY EFFICIENT THIN-FILM CDS CDTE SOLAR-CELL/

High-efficiency CdS/CdTe solar cells with thin CdS film have recently been developed. Semiconductive layers of CdS via the CVD method and of CdTe via the CSS method were deposited on an ITO/# 7059 substrate. Ce ll performance depends primarily on the thickness of CdS film, and the conversion efficiency is highest for a CdS film thickness of around 6 0 nm. Since the CdS film thickness decreases by about 30% during depos ition of the CdTe layer, a thickness of 95 nm is required to obtain a 60 nm-thick CdS film after deposition of a CdTe layer. By observing th e CdS film during the CdTe deposition process, a decrease was detected before CdTe layer completely covers the surface of the CdS film. By o ptimizing the thickness of CdS film, an efficiency of 15.12% for the b est cell under AM 1.5 verified at JQA was obtained. This fabrication p rocess has good reproducibility; 92.5% of 1 cm(2) solar cells fabricat ed under the same conditions have efficiencies above 14%.