II-VI compounds in solar energy conversion

Abstract

The principal advantages of II-VI compounds for terrestrial solar photovoltaics are low cost, direct bandgap, and the ease of deposition of good quality films of these materials by a variety of growth methods. Existing solar cell technology shows that a solar efficiency of 10% for all thin film, II-VI compoud cells will be reached within a year or two. This paper outlines the useful II-VI compounds and their preparation in this and discussions many of the heterojunctions which show promise. The interaction between the structural parameters of these films such as growth morphology and grain size and the electrical properties of the heterojunctions fabricated from them is crucial to producing efficient cells. Still very little research has been done in this area. The effect of grain boundaries in thin films and heterojunction lattice mismatch is demonstrated by simple models in this paper in order to gain a perspective on the required film properties and cell conjunctions. Finally experimental results are presented for a number of heterojunctions involving II-VI compounds, focusing particularly on the CdS/CdTe cell. © 1977.