A new strategy for monitoring the charge transfer from perovskite thin films to electron transport layers using a heterodyne transient grating technique

Abstract

We fabricated CH₃NH₃PbI₃ (MAPbI₃) thin films with and without a ZnO layer and measured the heterodyne transient grating (HD-TG) responses of each film to investigate the charge injection dynamics from MAPbI₃ to ZnO, based on the component arising from the recombination of the surface trapped electrons in the ZnO layer with the remaining holes in MAPbI₃. In addition, we observed the HD-TG response of the MAPbI₃ thin film coated with the ZnO layer in which phenethyl ammonium iodide (PEAI) was inserted between two layers as a passivation layer and confirmed that the charge transfer was enhanced when PEAI existed, based on the increase in the amplitude of the component arising from the recombination and its acceleration.