Zn_xCd_1-xS/Cu₂S heterojunction solar cells-II: junction analysis

Abstract

Cu₂S/Zn_xCd_1-xS heterojunction solar cells have been fabricated by two processes namely, spray pyrolysis and evaporation. The cells have been characterised in terms of the temperature dependence of the current-voltage and capacitance-voltage characteristics. Based on the analysis of the data, an energy band model has been proposed to explain the photovoltaic performance of the heterojunction. The dominant transport mechanism in both cases has been found to be interface recombination. The observed increase in open circuit voltage on increasing ZnS concentration has been understood on the basis of a reduction in the reverse saturation current caused primarily by an increase in the barrier height at the interface. The density of interface states is not observed to be significantly affected by the lattice parameter mismatch between Cu₂S and Zn_xCd_1-xS.