In-plane oriented CH₃NH₃PbI₃ nanowire suppression of the interface electron transfer to PCBM*

One-dimensional nanowire is an important candidate for lead-halide perovskite-based photonic detectors and solar cells. Its surface population, diameter, and growth direction, etc., are critical for device performance. In this research, we carried out a detailed study on electron transfer process at the interface of nanowire CH3NH3PbI3(N-MAPbI3)/Phenyl C61 butyric acid methyl-ester synonym (PCBM), as well as the interface of compact CH3NH3PbI3(C-MAPbI3)/PCBM by transient absorption spectroscopy. By comparing the carrier recombination dynamics of N-MAPbI3, N-MAPbI3/PCBM, C-MAPbI3, and C-MAPbI3/PCBM from picosecond (ps) to hundred nanosecond (ns) time scale, it is demonstrated that electron transfer at N-MAPbI3/PCBM interface is less efficient than that at C-MAPbI3/PCBM interface. In addition, electron transfer efficiency at C-MAPbI3/PCBM interface was found to be excitation density-dependent, and it reduces with photo-generation carrier concentration increasing in a range from 1.0 × 1018 cm−3–4.0 × 1018 cm−3. Hot electron transfer, which leads to acceleration of electron transfer between the interfaces, was also visualized as carrier concentration increases from 1.0 × 1018 cm−3–2.2 × 1018 cm−3.