A self-powered flexible UV-visible photodetector with high photosensitivity based on BiFeO3/XTiO3 (Sr, Zn, Pb) multilayer films

Abstract

Ferroelectric-based photodetectors have attracted much attention due to their suitable band gap and unrestricted photovoltage. However, their low photocurrent, responsivity, and detectivity are still big challenges. Herein, BiFeO₃/XTiO₃ (X = Sr, Zn, Pb) multilayer films are fabricated to realize a self-powered flexible UV-visible photodetector. This self-powered photodetector achieves fast and sensitive photodetection of UV-visible light due to the UV absorption layer XTiO₃, a strong built-in electric field in BiFeO₃, and the heterojunction electric field when the power density is 8 mW cm⁻². J–V and J–t curves were tested to determine the photovoltaic effect under UV-visible illumination, in which the rise and fall times of the photocurrent densities at zero bias are close to 20 ms with switching light and show excellent fatigue characteristics. In addition, good responsivity (7.4, 1.3 mA W⁻¹) and detectivity (7.5 × 10¹¹, 3 × 10¹⁰ jones) were achieved in the BiFeO₃/ZnTiO₃ film at zero bias under 365 and 500 nm illumination, respectively. Finally, the photodetection performance of the BiFeO₃/XTiO₃ multilayer films on flexible substrates was verified. The present work lays a foundation for the applications of ferroelectric-based self-powered UV-visible photodetectors.