Flexible Self‐Powered Photoelectrochemical Photodetector with Ultrahigh Detectivity, Ultraviolet/Visible Reject Ratio, Stability, and a Quasi‐Invisible Functionality Based on Lift‐Off Vertical (Al,Ga)N Nanowires

Abstract Flexible self‐powered ultraviolet (UV) photodetectors (PDs) with an invisible functionality are essential but challenging to be fabricated for the applications of next‐generation optoelectronic devices. In this work, a flexible photoelectrochemical (PEC) (Al,Ga)N PD with three excellent characteristics, which are the ultrahigh UV/visible reject ratio, ultrahigh detectivity, and transmissivity, is proposed and demonstrated successfully. By numerical simulations, it is also found that the cross‐sectional absorption area should be a nonignorable factor affecting the photogenerated current under bending states. After continuous long‐time working or preserving, the PD performance can keep quite stable. Thanks to the pretty thin bending section of GaN connecting layer, the piezoelectric charges generated by stress are proposed to have only a limited effect in the energy band and photocurrent density. Therefore, when bending or twisting the PD at a high degree for many times, both the stable on‐off switching characteristics and photocurrent densities can still be achieved. With the demonstrated ultrahigh detectivity and stability of flexibility, this PD would enable a broad range of optoelectronic applications, including omnidirectional UV detection and wearable intelligent sensors.