High‐Performance Se‐Based Photoelectrochemical Photodetectors Via in Situ Grown Microrod Arrays

Abstract Selenium (Se) is a p‐type semiconductor with a narrow bandgap, that holds great potential for application in the field of photodetectors because of its good optical properties. However, the photodetection performance of Se‐based photoelectrochemical photodetectors (PEC PDs) fabricated by the drop‐casting (DC) method is still far below the expected value. In this work, in situ grown t‐Se microrod array films (IS‐Se MAFs) are prepared on fluorine‐doped tin oxide (FTO) by a simple electrodeposition method at 353 K. PEC PDs consisting of IS‐Se MAFs as photocathodes show excellent self‐powered photodetection capability with a high responsivity of 10.38 mA W⁻¹, which is a 358‐fold increase over that of DC‐Se PEC PDs. The boosted photoresponse originates from the synergistic effect of the larger electrochemically active surface area and stronger light absorption of IS‐Se MAFs. Moreover, IS‐Se MAFs PEC PDs have a broadband photoresponse ranging from ultraviolet to near‐infrared, fast response speed, good multicycle, and long‐term stability. All the merits confirm the promising application of IS‐Se MAFs in high‐performance optoelectronic devices.