A self-powered triboelectric UV photodetector based on coupling impedance matching and photoresistive effect by sensing-electrode model

Self-powered photodetectors can satisfy the development demands of Internet of things towards minimization, integration, intelligence and multifunctionality. In this work, we have reported a self-powered triboelectric UV photodetector (SPTUD) based on coupling impedance matching and the photoresistive effect. A sensing-electrode model is validated through replacing the traditional electrode by ZnO nanoparticle film in a single-electrode mode triboelectric nanogenerator (S-TENG). Working both as the photoresistive material and electrode, the resistance variation range of the ZnO film matches well with the resistance dependence of S-TENG. The output voltage is significantly affected by the variations in variable resistances of ZnO film altered by UV light intensity due to the impedance matching effect. As a self-powered UV photodetector, the voltage signal of SPTUD increases from 0.5 V to 1.1 V with increasing light intensity from 0 to 0.61 mW/cm² under 375 nm UV light illumination. It can efficiently detect low-intensity UV light of 0.17 mW/cm² with a voltage responsivity of 2.66 V (mW cm⁻²)⁻¹. For demonstration, a wearable self-powered UV photodetection system based on the S-TENG and SPTUD is integrated in a bracelet. The reference-electrode and sensing-electrode are designed to connected with chip LEDs for visualized UV light photodetection to remind people to take effective measures for harmful UV light protection out of door. This work proposes the concept of sensing-electrode model, and we believe it will pave a new avenue for the next-generation of self-powered triboelectric sensors.