A fast-response and transparent solution–processed ultraviolet photodetector based on ZnO quantum–sized nanoparticles

Solution-processed ultraviolet (UV) photodetectors with high performance have great potential in many practical applications. In this paper, quantum-sized zinc oxide (ZnO) nanoparticles (~ 5.5 nm) were synthesized by a simple and low-cost chemical reflux method. The crystalline structure, morphologies, and optical properties of ZnO nanoparticles were investigated in detail. The results showed that the as-synthesized ZnO nanoparticles were wurtzite-structured (hexagonal) ZnO and had specific surface area as high as 68.3 m²/g, the ZnO nanoparticulate thin films had a strong absorption in UV region and optical bandgap of 3.28 eV. Furthermore, an UV photodetector was fabricated using the as-prepared ZnO nanoparticles, the device revealed stable, rapid and repeatable photoresponse towards 365 nm UV light, the sensitivity (S), responsivity (R), rise time (T_r), and decay time (T_d) of the photodetector was 11.4 at − 0.25 V, 22.1 A/W at 3 V, 1.8 s and 47.2 s, respectively. In addition, the photoresponsive mechanism of this UV photodetector was systematically illuminated according to the adsorption-photodesorption theory of oxygen in ZnO nanoparticles.