Thermally Restorable Optical Degradation Effects in Heat-Treated Cu2S–CdS Crystal Heterojunctions

Abstract

We have shown that heat treatment alone does not produce appreciable degradation of the short‐circuit current in Cu₂S–CdS single‐crystal photovoltaic heterojunctions. The degradation, which has been commonly observed, is the result of optically induced effects in the heat‐treated cell, subsequent to the heat treatment. These optically induced effects can be correlated with photochemical changes induced in single crystals of CdS: Cd: Cu in which the density of Cu acceptors exceeds the density of excess‐Cd donors. Major conclusions about the mechanism of the photovoltaic effect and heat‐treatment processes can be drawn.