Role of Reduced Graphene Oxide in Achieving High Efficiency\nof All-Inorganic Perovskite Solar Cells: An Experimental and Numerical\nInvestigation

Perovskite\n(PVT) solar cells (PSCs) have proven to be a viable\nand cost-effective alternative to silicon (Si) photovoltaic cells,\nparticularly due to their exceptional power conversion efficiency\n(PCE or η). Despite this, several device-level factors, including\ninterfacial charge carrier recombination, limit their performance.\nGraphene and its derivatives, notably reduced graphene oxide (rGO),\nare increasingly viewed as effective tools in interfacial engineering\nto safeguard PSC performance. For this reason, our investigation explores\nthe role of an rGO interfacial layer within an all-inorganic, cesium\n(Cs)-based, bromine (Br)-rich PSC. The first part of the study emphasizes\nthe synthesis of rGO layers, accompanied by rigorous structural, optical,\nand material characterization. Following this, a detailed numerical\nanalysis is performed on the rGO-integrated all-inorganic Cs-based\nPSC configuration: FTO/TiO<sub>2</sub>/CsPbIBr<sub>2</sub>/rGO/nickel\noxide/Au. The results provide a framework for optimizing the layer\nparameters of the rGO interfacial layer, PVT absorber, and charge\ntransport layers. The simulation findings indicated an impressive\nefficiency of 18.92% for the optimized device with a minimum absorber\ndefect density of 1 × 10<sup>13</sup> cm<sup>–3</sup>.\nThis work aims to elucidate the importance of using rGO interfacial\nlayers for improving the design and modeling of related PSCs.