A modeling study on utilizing SnS₂ as the buffer layer of CZT(S, Se) solar cells

CdS is conventionally used as the n-type buffer layer in chalcopyrite (CIG(S, Se)) and Kesterite (CZT(S, Se)) solar cells. CdS is toxic and there are wide attempts to find substitutes for it. Here, we suggest SnS₂ as a possible alternative. SnS₂ films were deposited by pulsed laser deposition (PLD), characterized to estimate carrier concentration and electron affinity values, and the obtained values were used to model a CZT(S, Se) solar cell. The experimental values of a benchmark CZT(S, Se) cell with efficiency of 12.3% were employed to obtain the density and energy position of defects in CZT(S, Se) and validating the model. We observed that SnS₂ results in almost identical performance as CdS, showing slightly better current density, due to smaller conduction band offset of 0.21 eV compared to 0.28 eV for CdS.