An Investigation for Electron Transport Layer Material for Efficient Perovskite Solar Cell

Abstract

In perovskite solar cell (PSC) technologies, the electron transport layer (ETL) plays a significant role. Despite the fact that ETL-free planar-type PSCs have been reported, their highest Power conversion efficiency (PCE) is only 14.14 percent, much lower than that of ETL-containing cells, illustrating the necessity of the ETL in this configuration of PSCs. For high device efficiency, an appropriate ETL should meet a few basic parameters. For example, good optical transmittance to ensure that enough light is transmitted into the perovskite absorber, matched energy levels with perovskite materials to produce the expected open-circuit voltage (Voc), and high electron mobility to effectively extract carriers from the active layer to avoid charge recombination. In planar-type PSCs, fast carrier extraction is desired to limit charge accumulation at the interface due to ion migration and eliminate hysteresis. Thus, for high PCE devices, the focus has been on building high-quality ETLs with appropriate energy levels and high electron mobility. This paper, covers electron-transporting layer-free construction, features of electron transporting layer, and techniques to improve ETL performance using a variety of materials such as TiO₂, ZnO, SnO₂, EDTA, E-SnO₂, and WO₃.