Hydrogel Based UV Photodetector Based on Polarization of Free Water Molecules

Abstract Conductive hydrogels retain the intrinsic softness and elasticity that are hallmark features of traditional hydrogels, and they also assimilate the electrical properties of the embedded conductive materials. Conventional epitaxial growth techniques for heterojunctions require precise lattice matching between adjacent materials, significantly limiting technological advancements in photodetector innovation. The integration of conductive hydrogels with semiconductors to fabricate photodetectors presents a feasible solution that bypasses the traditional lattice matching constraints inherent in the epitaxial growth of heterojunction semiconductor photodetectors. Herein, device integration is enhanced by developing a transparent conductive hydrogel, positioned between graphene and gallium nitride, which effectively mitigates the fluidity issues of the polar liquid complicating device encapsulation. A comprehensive analysis of the photodetection characteristics of the graphene/conductive hydrogel/gallium nitride heterostructure is conducted, thereby establishing its structural framework. Flexible transparent devices are further prepared based on PEDOT/Alg (Ca 2+ ) and demonstrate their potential application in 360 ° omnidirectional photodetection. This work introduces a novel approach for the enhanced integration of hydrogel‐based spectrally selective and flexible transparent photodetectors.