High Performance Broadband Photoelectrochemical Photodetectors Based on Cu-doped Bi2O2 Se Nanosheets

Abstract

Two-dimensional material Bi2O2Se has emerged as a promising candidate for photoelectrochemical (PEC) applications due to its moderate bandgap, strong light-matter interaction, and excellent environmental stability. However, its practical use is limited by high carrier recombination rates and poor charge transport properties.To address these issues, this study proposes a copper (Cu) doping strategy to tailor the band structure and interface kinetics, and synthesizes ultrathin Cu-doped Bi 2 O 2 Se (CBOS) nanosheets via a facile hydrothermal method. The resulting CBOS-based PEC photodetector exhibits significantly enhanced performance: a photocurrent density of 28.46 μA/cm², which is 7.9 times that of pure Bi2O2Se, a responsivity of 10.78 mA/W, and an ultrafast response (both rise/decay times of 60 ms). The device enables broad-spectrum detection from 365 to 700 nm in a self-driven mode (0 V bias), with performance tunable via external bias (up to 0.6 V) and electrolyte concentration. Remarkably, it retains 85% of its initial photoresponse after one month of storage, demonstrating outstanding stability. This study realizes the synergistic enhancement of light harvesting, carrier transport, and photocurrent simultaneously through element doping, providing critical proof-of-concept for the structural design and performance modulation of high-efficiency materials for PEC applications.