Effect of KF Addition to (Cu,Ag)2SnS3 Thin Films Prepared by Sulfurization Process

Abstract

(Cu,Ag)2SnS3 thin films and solar cells are prepared by sulfurization of KF/Sn/(Cu + Ag) stacked precursors in a sulfur and tin mixing atmosphere. Their properties are investigated. Stacked KF/Sn/(Cu + Ag) precursors are deposited on Mo/soda lime glass substrate by sequential evaporation of Cu + Ag, Sn elements, and KF. The molar ratios of the evaporation materials are held constant at (Cu + Ag):Sn = 1.0:0.6 and Ag/(Cu + Ag) = 0.05, and the KF/Cu molar ratio is changed from 0 to 0.05. The precursors are crystallized by annealing for 30 min at 570 °C in a sulfur and tin mixing atmosphere. The compositions are approximately constant, and the dependence of the composition ratio on the KF addition quantity is not observed. For all samples, the X‐ray diffraction patterns and the Raman spectra corresponding to CATS are obtained. The values of Voc increased with increasing KF/Cu molar ratio until KF/Cu = 0.03. The best solar cell in this study showed a Voc of 248 mV.