Engineer carrier transport at (Al,Ga)N nanowire/hydrogel interface to realize self-driven ultraviolet photodetectors with switchable response speed for imaging system

Multi-functional photodetector is very important in spectral information acquisition but is difficult to implement. In this work, a self-driven multifunctional ultraviolet photodetector based on (Al,Ga)N nanowire/hydrogel interface is proposed and demonstrated successfully. It is found that the conventional photodetector has two functional interfaces with the full contact between nanowires and liquid-electrolyte, which is very difficult to modulate the competition carrier transport process. Thanks to the design of local contact between (Al,Ga)N nanowires and quasi-solid hydrogel, only one functional interface operates in the photodetector, achieving the slow/fast response speed over 20 times difference at 0 V bias (1080/1217 ms under 310 nm illumination and 46/45 ms under 365 nm illumination). Such unique behavior of switchable response speed is mainly attributed to the balance of dynamic carrier transport across the (Al,Ga)N/GaN and nanowire/hydrogel local contact interfaces. Moreover, the local contact interface proves excellent reusability and the photocurrent density remains at 94.7% after preserving for 2 months. Particularly, taking advantage of the slow/fast response characteristic, the proposed self-driven ultraviolet photodetector is demonstrated to have the ability to distinguish light wavelengths and can be integrated with hydrogel into an array detection system for the image display.