Enhance the responsivity and response speed of self-powered ultraviolet photodetector by GaN/CsPbBr3 core-shell nanowire heterojunction and hydrogel

Due to the low power consumption, self-powered ultraviolet (UV) photodetectors (PDs) are essential for the next-generation optoelectronic applications. In this work, it is pretty novel to demonstrate a self-powered photoelectrochemical (PEC) UV PD based on gallium nitride/cesium lead bromide (GaN/CsPbBr3) core-shell nanowire (NW) heterojunctions. The GaN/CsPbBr3 core-shell NW heterojunctions are formed efficiently by introducing the CsPbBr3 quantum dots (QDs) with cubic phase onto the GaN NW surfaces. In the PEC PDs, CsPbBr3 QDs can act as both light harvester and hole conductor. The appropriate energy level alignment could be a key reason contributing to the efficient increase of carrier separation and transport. Furthermore, it is found that the QD quantity and the spacing of GaN/CsPbBr3 core-shell NWs can affect the PD performance significantly. With an appropriate quantity of CsPbBr3 QDs, GaN/CsPbBr3 core-shell NWs can not only enhance the photocurrent and responsivity significantly, but also accelerate the response speed by reducing the fall time. Thanks to the further introduction of the hydrogel, we can decrease the PD volume remarkably by working without water. It is also found that the hydrogel can accelerate the response speed significantly by reducing the path for carrier transport, which has the potential to develop the new practical PDs with high performance.