THIN-FILM CADMIUM TELLURIDE SOLAR-CELLS

Cadmium telluride has long been recognized as a promising thin film photovoltaic material. Polycrystalline thin film CdS/CdTe heterojunction solar cells have been prepared by several techniques with various degrees of success. In this work the inverted configuration p-CdTe/CdS/SnO//2:F/glass was prepared by the deposition of p-CdTe films onto CdS/SnO//2:F/glass substrates using chemical vapor deposition and close-spaced sublimation (CSS). Chemical vapor deposition has the advantage of controlling the electrical resistivity of p-CdTe films whereas the CSS technique is capable of depositing p-CdTe films at high rates. The CdTe films deposited by the two techniques have different microstructures. The CSS process is simpler and the cleanness of the substrate surface is an important parameter in determining the electrical and photovoltaic characteristics of the heterojunctions. Solar cells of area 1 cm**2 or larger with an air mass 1. 5 (global) efficiency of 10. 5% were prepared and their junction properties were characterized.