Investigation of the Charge Injection from Organometal Halide Perovskite to a Hole Transport Layer Using a Heterodyne Transient Grating Spectroscopic Technique

The responses of MAPbI3 coated by ZnO with and without CuSCN were observed using near-field heterodyne transient grating spectroscopic technique for the investigation of the effect of the insertion of CuSCN, the hole transport layer, on the hole transfer efficiency in the perovskite-based solar cell. We revealed that the recombination arising from the surface trapped electrons in ZnO, the electron transport layer, was retarded when CuSCN was inserted in the film, which could be attributed to the spatially separated charge carriers more sufficiently, caused by the increase in the distance between the electron transport layer and the conducting substrate.