Dipolar Interlayers in Perovskite Solar Cells

A typical perovskite solar cell (PSC) is composed of a perovskite layer, electron/hole transport layer(s), cathode, and anode, producing several interfaces between these functional layers. These interfaces undoubtedly have great influence on the device performance. Introducing the dipolar interlayer is one of the most significant interface engineering strategies in PSCs, which helps to improve the charge extraction and collection and has made critical contribution to the fast development of PSC technology. Herein, the progress in the use of dipolar interlayers to promote the performance of PSCs is summarized. The dipolar interlayers in PSCs based on the device structure are categorized and the effect of each type of dipolar interlayer on the interface energy-level structure, interface charge transport and recombination, the interface defect passivation, perovskite morphology, and the device performance is discussed. A perspective on how to develop more effective dipolar interlayer materials and further enhancing the device performance from the viewpoint of the interface and dipolar interlayers is given.