Influence of low-temperature heat treatment on electronic properties in Cu 2 ZnSn(S,Se) 4 /CdS solar cells

This work aims at studying the effects of modifying structure and properties of CdS buffer layer on the electrical performance in Cu 2 ZnSn(S,Se) 4 solar cells, by using a low-temperature heat treatment. The V oc and FF in Cu 2 ZnSn(S,Se) 4 solar cells annealed at 200 °C have increased from 300 mV and 36.9% to 325 mV and 52.3%, leading to improvement of the conversion efficiency from 2.85 to 4.38%. Experimental analysis combined with first-principle calculations suggest these phenomena mentioned above are possible attributed to the enhancement of the conduction band minimum of CdS semiconductor induced by phase transition.