Nondestructive passivation of the TiO2 electron transport layer in perovskite solar cells by the PEIE-2D MOF interfacial modified layer

Abstract

The industrialization of perovskite solar cells (PSCs) is based on the development of efficiency and stability. Here, a composite film of a polyethylenimine ethoxylated (PEIE) and tellurophene-based two-dimensional metal–organic framework (2D MOF) was introduced to realize the nondestructive passivation of TiO₂. This interfacial layer can not only realize the effective passivation of TiO₂, but can also further improve the morphology of the perovskite film. After the modification of the PEIE-2D MOF composite film, the morphology and crystallinity of the perovskite film are greatly optimized, the trap states in the TiO₂ layer are reduced, and the electron transport in the device is enhanced, thus finally achieving highly efficient and stable FA_0.25MA_0.75PbI₃ PSCs with a maximum efficiency of 22.22%. It was demonstrated that the reduced trap states and the smooth surface of the TiO₂ electron transport layer are the reasons for the high performance of modified PSCs. This method provides a new way for improving the interface state to achieve highly efficient and stable PSCs.