Effect of Cu content on the photovoltaic properties of Cu(In,Ga)Se-2 solar cells prepared by the evaporation of binary selenide sources

Abstract

A Cu(In,Ga)Se-2 light-absorbing layer was prepared by a three-stage process employing the evaporation of In2Se3, Ga2Se3, and Cu2Se. The Cu content in the layer was adjusted by controlling the third-stage evaporation time. A sturdy n-CdS/p-CIGS junction was realized when the Cu content in Cu-x (In0.66Ga0.34)Se-2 was approximately 0.87, and the diode and photovoltaic parameters were also improved. At this condition, the doping concentration and junction depth were 7x10(15)cm(-3) and approximately 650 nm, respectively. The current collection efficiency in red light and longer wavelengths was improved in the sturdy junction. The efficiency of CdS/Cu(In,Ga)Se-2 solar cell was 13.4% when the composition of CIGS film was Cu-0.87(In0.66Ga0.34)Se-2.