The sodium effects on the CTS thin-film solar cells prepared on alkali-free glass substrate

Abstract

Cu₂SnS₃ (CTS) is considered to be a suitable candidate for future use as the absorber layer in thin-film solar cells. In this study, CTS films were formed by co-evaporation of Cu, Sn and S on alkali-free glass substrate (Corning EAGLE XG). After deposition, NaF was deposited on the CTS thin films. After NaF deposition, the NaF-deposited CTS films were annealed in a carbon container with sulfur. After annealing, the sample was dipped in deionized water to remove residual NaF. As the results, the grain size of the films with NaF deposition was larger than that of the films without NaF deposition, and the power conversion efficiency of the CTS thin film solar cells were improved by annealing with sodium deposition.