Self‐Powered and High‐Performance Alternating Current Photodetectors to enhance Broadband Photodetection

Abstract Self‐powered broadband photodetectors that are easy to fabricate and convenient to operate are highly desirable in numerous optoelectronic applications; however, achieving a fast response time with high sensitivity remains a daunting challenge to their widespread use. In this study, a self‐powered, high‐performance alternating current photodetector is fabricated by coating plasmonic Au nanoparticles (NPs) onto MoO 3 . The self‐powered photodetector shows high detectivity ( ≈ 4.6 × 10 10 Jones) and a good responsivity of 3.8 µ A W −1 , due to the alternating current photovoltaic effect. The photodetector exhibits a rapid response with the rise and fall times of 35 and 48 ms, respectively, under self‐biased conditions. Conductive atomic force microscopy demonstrates nanoscale charge transport and current generation, suggesting the possibility of fabricating a sub‐nanometer ( ≈ 50 nm) sized photodetector. Results thus observed are attributed to the relative shift and realignment between quasi‐Fermi levels under non‐equilibrium conditions, caused by inhomogeneous charge carrier generation. The results presented in this study introduce a simple approach to enhance self‐powered broadband photodetection while enabling high‐performance for advanced optoelectronic applications in the future; these applications include smart security, optical communication, digital display, and sensing, amongst others.