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.