Self-powered dual-wavelength polarization-sensitive photodetectors based on ZnO/BiFeO3 heterojunction

Abstract

The ferroelectric-photovoltaic (FE-PV) devices have received growing attention for the FE polarization-induced internal electric field to facilitate the separation and transport of the photogenerated electron-hole (e-h) pairs in the FE semiconductors. However, the low photocurrent output of the FE-PV devices is still a key challenge for the application and development of these devices. Here, ZnO/BiFeO3 (BFO) heterojunction photodetectors (PDs) are designed to utilize the built-in electric field at the heterojunction interface of ZnO nanoparticles (NPs)/BFO and the spontaneous FE polarization field of BFO to promote the separation and transport of the photogenerated carriers. ZnO nanorod arrays (NRs) grown on ZnO NPs provide a directional transport channel for the photogenerated electrons. ZnO/BFO heterojunction devices demonstrate a self-powered photoresponse in the ultraviolet (UV) and visible (vis) dual-wavelength. The devices show a responsivity of 1.32 mA/W, response time (τrise/τdecay) of 12.6/44.9 ms at 420 nm light illumination. In addition, the polarization imaging function of ZnO/BFO PDs is explored by extending the polarization photocurrent mapping values of a single PD unit to a complex array of optical information image processing utilizing the polarization-sensitive properties of BFO without external bias.