Revealing Electrical‐Poling‐Induced Polarization Potential in Hybrid Perovskite Photodetectors

Despite recent rapid advances in metal halide perovskites for use in optoelectronics, the fundamental understanding of the electrical‐poling‐induced ion migration, accounting for many unusual attributes and thus performance in perovskite‐based devices, remain comparatively elusive. Herein, the electrical‐poling‐promoted polarization potential is reported for rendering hybrid organic–inorganic perovskite photodetectors with high photocurrent and fast response time, displaying a tenfold enhancement in the photocurrent and a twofold decrease in the response time after an external electric field poling. First, a robust meniscus‐assisted solution‐printing strategy is employed to facilitate the oriented perovskite crystals over a large area. Subsequently, the electrical poling invokes the ion migration within perovskite crystals, thus inducing a polarization potential, as substantiated by the surface potential change assessed by Kelvin probe force microscopy. Such electrical‐poling‐induced polarization potential is responsible for the markedly enhanced photocurrent and largely shortened response time. This work presents new insights into the electrical‐poling‐triggered ion migration and, in turn, polarization potential as well as into the implication of the latter for optoelectronic devices with greater performance. As such, the utilization of ion‐migration‐produced polarization potential may represent an important endeavor toward a wide range of high‐performance perovskite‐based photodetectors, solar cells, transistors, scintillators, etc.