Light-induced molecular dipole reordering in halide perovskites

Light-induced molecular dipole’s orientation has been suggested to be a critical degree of freedom to affect the performance of hybrid perovskite-based optoelectronic devices. In this work, we utilized light-illuminated cross-sectional scanning tunneling spectroscopy to map simultaneously the organic cation’s dipole orientation and the corresponding electrostatic potential with atomic resolution. Our discovery provides real space experimental evidence of the dipole reordering under illumination to create a deep one-dimensional potential energy well. The result may be directly responsible for the efficient carrier transport and suppressed carrier recombination of hybrid perovskite as an excellent photovoltaic and optoelectronic material.