Boosting Photoresponse of Self‐Powered Photoelectrochemical Photodetectors via Planar Interdigital Electrodes

Abstract Underwater optical communications (UOC) and light imaging have aroused tremendous attention due to the ever‐growing exploration of marine resources. Photoelectrochemical‐type photodetectors (PEC PDs) have good application potential in underwater optoelectronic devices because of their intrinsic aqueous operation characteristics with a self‐powered function and high sensitivity. However, most of the currently reported PEC PDs consist of sandwich‐like device structures, increasing the weight, volume, and complexity of the devices. Here, a planar interdigital electrode (IE) structure for high‐performance self‐powered PEC PDs for the first time is proposed. The CuO‐based IE PEC PDs achieve good photoresponse in the wide region of 365–850 nm with a high responsivity of 21.86 mA W⁻¹ (455 nm irradiation), a fast response time (0.02/0.17 s), and good stability in artificial seawater. The good photoresponse is attributed to the promotion of interfacial electrochemical reaction kinetics and the accelerated charge transport by IE structure. Moreover, the CuO‐based IE PEC PDs show good UOC and underwater light imaging capability. Furthermore, the IE structure successfully applies in p‐Se and CuSe PEC PDs, demonstrating its good universality. The simpler structure and good photoresponse demonstrate that IE structure provides a new perspective for designing high‐performance, low‐cost, and self‐powered PEC PDs.