Recent progress in electron transport bilayer for efficient and low-cost perovskite solar cells: a review

Today, organic–inorganic perovskite hybrid solar cells are especially attracted by the energy industries to design and develop new-generation photovoltaic devices. They are the most promising materials for high PCE and cheap solar cells. They can also solve the current energy demand of society and the global crisis. Over the past few years, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased rapidly from 3.8 to 24.2%. However, the review focuses on the recent development of the electron transport layer due to the most important parameter perovskite solar cells to enhance the performance and stability of the device. These summaries discuss device architectures, single and double electron transport (ETL) layers, ETL optimization, and perovskite active layer interface for efficient perovskite solar cells. Moreover, the doping effects on the charge transport layer/window layers of PSCs were reviewed. In addition, the performance and stability issues for organic–inorganic halide perovskite solar cells are discussed here. Finally, future research on bilayer ETL and the perovskite active layer interface was also offered.