Influence of Cd, S and Na atoms on photoluminescence in tin sulfide thin films

The fundamental defects around the p-n interface were analyzed based on low temperature photoluminescence measurements to determine the origin of the various defects around the n-CdS/p-SnS structure in tin sulfide (SnS) solar cells. Particularly, the effects of Cd, S, and Na atoms on PL at the interface of a CdS layer and various treated SnS layers were examined. The PL peaks at 1.08 and 1.23 eV in the CdS/SnS structure, which were observed using the Cd partial electrolyte-treated SnS film, were associated with the formation of Cd-related defects. Furthermore, the PL peak at 1.27 eV in the CdS/SnS structure, which was observed using the sulfurized-SnS film and the excess Na-diffused SnS film, was associated with the formation of S-related defects such as O_S defects. These findings present considerable potential for improving the efficiency of SnS solar cells.