CsGeI3 perovskite-based solar cells for higher efficiency and stability: an experimental investigation

Abstract

Among the recent developments in photovoltaic technologies, perovskite solar cells (PSCs) have drawn significant attention, owing to their exceptional power conversion efficiency (PCE), cost-effectiveness, and better optoelectronic characteristics. However, the stability and presence of lead (toxicity) in PSCs remains a major challenge to their commercialization. In this study, we experimentally investigated all-inorganic, lead-free CsGeI3-based PSCs in an n-i-p configuration. The CsGeI3 films were synthesized using a one-step spin-coating technique and their crystallographic characteristics were analyzed. Furthermore, we fabricated and tested different device architectures incorporating CsGeI3 as the absorber layer with various electron transport layers (ETLs), including TiO2, ZnO, and graphene oxide (GO), while employing MoS2 as the hole transport layer. The resulting device structure was Fluorine doped Tin oxide (FTO)/(TiO2/ZnO/GO)/CsGeI3/MoS2/Ni). All fabricated devices demonstrated excellent performance, with the TiO2-based ETL device achieving the highest PCE of 10.79%. In addition, incorporating reduced graphene oxide (rGO) as an interface layer on top of the absorber layer further enhanced photovoltaic performance by approximately 3% across all configurations (achieving outstanding efficiency of 13.57%). The hydrophobic nature and high conductivity of rGO suggest its potential as a promising strategy for improving the stability and efficiency of lead-free PSCs in future applications.