Development of silver nanoparticle decorated ZnO nanorod array-based highly sensitive and flexible UV-photodetector

Abstract

ZnO-based UV photodetectors are highly desired for various applications, viz., wearable dosimeter, biomedical, defense, and communications. This work reports a ZnO-based photoconductive device with inter-digitated planar silver electrodes deposited over ZnO nanorod array (NRA), capped with silver nanoparticles. The FESEM image confirmed the growth of ZnO NRA. The photosensitive devices thus developed were found to be stable in air, showing high photosensitivity of 4.2 x 107, against a λ=330 nm UV light illumination, demonstrating a high UV-Vis rejection ratio. The ZnO nanorod array (NRA) was deposited via the hydrothermal technique over functionalized and precleaned polyimide substrates. These substrates were then capped with silver nanoparticles (Ag-NPs) using the photochemical reduction technique. ZnO NRA capped with Ag-NPs demonstrated improved photosensitivity and responsivity, compared to the devices developed using pristine ZnO, especially for small-sized silver nanoparticles. These observations were corroborated to the plasmonic coupling between Ag-NPs and ZnO NRs. The intensity of light was maintained at 0.8 mW/cm2. Additionally, these devices were developed on the polyimide substrate, hence they were flexible and could sustain multiple bending cycles (~100) without showing any significant degradation in their performance. This work demonstrated the potential of effective plasmonic coupling between Ag-NPs and ZnO NRs and its effective utilization towards the development of highly sensitive UV photodetectors, and also highlights the potential of this effective solution-processed-based technique in the development of highly sensitive, air-stable, flexible UV photodetectors.