Advances in electron and hole transport layers-free perovskite solar cells

Abstract Perovskite solar cells (PSCs) represent a transformative photovoltaic technology, yet their commercialization is hindered by the complexity associated with charge transport layers i.e., electron transport layer (ETL) and hole transport layer (HTL). This review focuses on the significant progress made in simplifying PSC architecture by eliminating the ETL and HTL. The removal of these layers directly addresses key manufacturing hurdles, offering a route to reduced production costs, streamlined fabrication, and potentially enhanced stability. The efficiencies for ETL- free and HTL-free PSCs are becoming increasingly with recently reported over 22%. The overcoming of interfacial recombination losses and ensuring robust operational stability are the foremost challenges that will define the future research and development of charge transport layers free perovskite photovoltaics. We have further examined the role of compositional engineering, interface modification, and novel deposition techniques in enabling high performance and stability in transport-layer-free PSCs.