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

Perovskite (PVT) solar cells (PSCs) have proven to be a viable and cost-effective alternative to silicon (Si) photovoltaic cells, particularly due to their exceptional power conversion efficiency (PCE or η). Despite this, several device-level factors, including interfacial charge carrier recombination, limit their performance. Graphene and its derivatives, notably reduced graphene oxide (rGO), are increasingly viewed as effective tools in interfacial engineering to safeguard PSC performance. For this reason, our investigation explores the role of an rGO interfacial layer within an all-inorganic, cesium (Cs)-based, bromine (Br)-rich PSC. The first part of the study emphasizes the synthesis of rGO layers, accompanied by rigorous structural, optical, and material characterization. Following this, a detailed numerical analysis is performed on the rGO-integrated all-inorganic Cs-based PSC configuration: FTO/TiO₂/CsPbIBr₂/rGO/nickel oxide/Au. The results provide a framework for optimizing the layer parameters of the rGO interfacial layer, PVT absorber, and charge transport layers. The simulation findings indicated an impressive efficiency of 18.92% for the optimized device with a minimum absorber defect density of 1 × 10¹³ cm^-3. This work aims to elucidate the importance of using rGO interfacial layers for improving the design and modeling of related PSCs.