Enhancing the performance of self-powered BiFeO₃-based photodetectors through the coupling effect between gradient electric field and Schottky barrier potential

In light of the growing demand for autonomous sensing technologies driven by the Internet of Things and wearable electronics, there is an increasingly urgent need for the development of high-performance self-powered photodetectors. Bismuth ferrite, with its unique narrow bandgap and robust ferroelectric photovoltaic effect, has emerged as a promising material for the next-generation optoelectronic devices. This study presents a novel device architecture for a self-powered photodetector on the basis of (Dy, Ni)-gradient-doped BiFeO₃ multilayer film. This self-powered photodetector demonstrated exceptional photoelectric performance, with a responsivity of 1.5 mA/W and a detectivity of 9.85 × 10⁹ Jones. An underlying mechanism was proposed herein that the gradient doping establishes a spatial variation in the distribution of oxygen vacancies, which triggers the coupling effect of the oxygen vacancy gradient field and Schottky barrier field. This synergistic interaction significantly facilitates the separation and transport of photo-generated carriers, thereby enhancing the device performance. The findings in the paper not only provide a strategy for optimizing BiFeO₃-based optoelectronics but also offer significant insights into the development of self-sustained and integrated sensing nodes.