Recent Developments in Low-Temperature Solution-Processed Metal Oxide Electron Transport Layers for Perovskite Solar Cells

With power conversion efficiency (PCE) exceeding 25%, perovskite solar cells (PSC) have become known as a remarkable photovoltaic technology in the last few years. Further, the low preparation temperature and facile processing techniques specifically in the planar architecture have contributed immensely to the production of inexpensive solar devices. The charge transport layers, primarily the electron transport layer (ETL) play a significant role in efficient charge extraction and transport from the absorber layer to the respective electrode. In particular, numerous research have been carried out. on the oxides of metal (MOX) based ETL owing to their exceptional optoelectronic characteristics, low cost, and remarkable adaptability. This review deals with the application of newly developed MOX-based ETLs processed at low temperatures for planar PSC. The optical and electrical characteristics of widely used MOX ETL were briefly investigated and explored for impact on the photovoltaic (PV) stability and performance of halide PSC. In the end, the future perspective on the MOX ETL was also offered.