Recently, perovskite-based photovoltaics have started to be considered as possible next-generation solar cells for applications. The traditional-architecture perovskite photovoltaics (n-i-p type) have a sandwich-like structure with metal halide perovskites as active elements, metal oxides as the electron-transport layer, and organic materials as the hole-transport layer. While this type of solar cells shows good performance, high-temperature annealing is required for the preparation of metal oxides. This has become a bottleneck for the large-scale fabrication of solar cells for practical applications. To address this problem, inverted perovskite solar cells (PSCs, p-i-n type) without metal oxide layers are becoming the research focus due to their low-temperature and solution-based processing.
the advantages of metal-oxide-free inverted perovskite solar cells, it is still very challenging to find suitable organic electron transport layer (ETL) which are easily synthesized at low cost and which can be easily solution-processed to achieve high-performance devices. Based on our research, we believe that could be promising ETL to boost the efficiency of inverted perovskite solar cells.