Abstract:The double perovskite Cs2SnI6 has notable optical and electrical characteristics, rendering it a highly prospective candidate for deployment as the absorber layer in perovskite solar cells (PSCs). We simulated the performance of PSCs using lead-free Cs2SnI6 double perovskite absorber layer and graphene derivatives, namely graphene oxide (GO) and reduced graphene oxide (rGO), as hole transport layers (HTLs). Our findings show that rGO offers an excellent hole extraction property with minimal interfacial recombination compared to GO. PSC utilizing rGO as the HTL material achieved a power conversion efficiency (PCE) of 19.07%, while those employing GO HTL attained only 16.9%. The superior performance of rGO is attributed to its greater charge carrier mobility of rGO and its favorable energy level alignment with the double perovskite absorber layer. In contrast, the mismatch in the charge transport properties between the absorber layer and the GO HTL resulted in poor performance. Our study showcases the potential of using graphene derivative-based HTLs for realizing lead-free PSCs.