Controllably modulated asymmetrical photoresponse with a nonvolatile memory effect in a single CH3NH3PbI3 micro/nanowire for photorectifiers and photomemory

Abstract

Nanostructured hybrid organic–inorganic perovskites exhibit remarkable photodetection performance due to their abundant surface states and high responsivity to visible light. However, in traditional photodetectors with a symmetrical configuration of two-terminal electrodes, the photoresponse is independent of bias polarity. Moreover, for self-powered photodetectors, an asymmetric structure of the chemical composition, such as p–n and Schottky junctions, and two different electrodes are necessary. Herein, we demonstrate a modulable asymmetrical photoresponse by packing only one electrode end in a single CH₃NH₃PbI₃ micro/nanowire with two symmetrical Ag electrodes. This not only enables the high performance of light- and bias-modulated multifunctional photorectifiers and self-powered photodetectors, but also allows controllable implementation of nonvolatile photomemory with a tunable spectral responsivity and range. At an unpacked electrode interface, trace moisture in the environment promotes a good bonding of Ag⁺ and I⁻, substantially decreasing the interface barrier. Conversely, at a packed electrode interface, abundant surface states can be well preserved, leading to a high interface barrier. Notably, under a large voltage and strong light, the redox of Ag/AgI at the unpacked electrode interface and the injection and ejection of holes at the packed electrode interface can be reversibly conducted by inverting the voltage polarity, enabling a controllable nonvolatile modulation. Therefore, by clarifying the actual origin of the photoelectrical response of CH₃NH₃PbI₃ micro/nanowires at electrode interfaces, high-performance multifunctional photorectifiers and self-powered photodetectors based on asymmetrical interface photovoltaic effects with two symmetrical electrodes can be controllably realized. Furthermore, by precise cooperative modulation of two electrode interface states with a large voltage and strong illumination, nonvolatile photomemory with a tunable spectral responsivity and range can be implemented.