Discovery of a novel visible-light-active photodetector based on bismuth ferrite: constructing and optimizing the Cr-doped-BiFeO3/NiO thin film heterostructure

Bismuth ferrite (BFO) with narrow bandgap (<2.70 eV) is an uprising star in the application of opto-electronic conversion in visible (Vis) region. Fe-site doping by transition metals is a recognized strategy to reduce leakage current in order to create more qualified BFO-based optoelectronic devices. We aim to constitute the heterostructure of BiFe1-xCrxO3 (BFCO) coupling to hole-transporter NiO, serving as Vis-active photodetector with superior photoresponse speed. The influence of Cr doping ratio on BFCO is systematically investigated, indicating that doping Cr can effectively restrain not only the reduction of Fe3 thorn state but also the generation of oxygen vacancies. Moreover, by taking advantage of desirable energy-band alignment, BFCO/NiO heterojunction can reach the optimized response time constants of photocurrent rising and decay, i.e., Tr and Td are, respectively, lowered down to 0.23 and 0.38 ms, which are almost two order-of-magnitude lower than that of pure-BFO/NiO and also more than one order-of -magnitude lower than that of single-layer BFCO film. It confirms an overwhelming photoresponse per-formance over other Vis-active counterparts. Herein, we for the first time achieve the Vis photodetector based on BFCO, by virtue of functional interfacial structure of BFCO-NiO to energetically separate pho-togenerated electron-hole pairs as well as improve charge carrier transportation. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, adding Cr doping effectively suppresses the generation of Fe3+ vacancies and oxygen vacancies in BiFe1-xCrxO3 (BFCO). The BFCO/NiO heterojunction achieves optimized photoresponse time, with significantly reduced response time constants compared to pure-BFO/NiO and single-layer BFCO film. This research successfully demonstrates a visible-light photodetector based on BFCO, with superior performance.