Research and development of modification strategies based on all inorganic perovskite solar cells

In recent years, perovskite solar cells (PSCs) have developed rapidly, with their power conversion efficiency (PCE) even rivaling that of crystalline silicon (Si) solar cells, making them a leader in the field of photovoltaics (PV). All inorganic PSCs, especially CsPbI₂Br perovskite, have attracted widespread attention and research because of their outstanding thermal stability, appropriate trade-offs and band gap suitable for tandem solar cells. Due to the replacement of organic components, all inorganic PSCs have also circumvented the stability issues associated with organic molecules. In order to further promote the commercial development of CsPbI₂Br PSCs, carbon hydrophobic materials are introduced as hole transport layer (HTL) and back electrode, which can not only meet the challenges of humidity stability, but also simplify the preparation process and reduce the cost. Since the first report of carbon-based perovskite solar cells (C-PSCs) in 2016, the efficiency and stability of the devices have significantly improved. The current research work has proposed a series of strategies to enhance the performance of the device, including optimizing the preparation process, optimizing the charge transport layer, solvent engineering, additive engineering, interface modification, etc. This review mainly summarizes the research progress of CsPbI₂Br C-PSCs, and briefly mentions the development and application of CsPbI₂Br perovskite in the tandem solar cells, carbon-based flexible PSCs, semitransparent PSCs and large area devices, finally, the challenges in the field of CsPbI₂Br PSCs are discussed, and a prospect for future research is presented.