Performance improvement of ZnO/P3HT hybrid UV photo-detector by interfacial Au nanolayer

In this study, a hybrid ultraviolet (UV) photo detector comprising of hydrothermally grown highly oriented Zinc Oxide nanorod arrays (ZnO NRAs) and Poly(3-hexylthiophene-2,5-diyl) (P3HT) as an active layer was fabricated and characterized. These hybrid photo detectors demonstrated a high rectification ratio (similar to 117) and responsivity of 10.7 A/W at -2 V under incident light of wavelength 325 nm. Further to investigate the effect of surface plasmon property of metal nanoparticles on the performance of hybrid DV photo detectors, ZnO NRAs were capped with de sputtered gold (Au) metal nanolayer (similar to 5 nm) at the ZnO-P3HT interface, prior to coating P3HT layer on top of it. It was found out that upon Au coating the absorption of the ZnO was enhanced partly in the ultraviolet and visible region. In consequence the rectification ratio and responsivity of the hybrid photo detector was enhanced drastically from 117 to 1167 and 10.7 to 17.7 A/W respectively. Interestingly the reduction in dark current was observed on Au coating and it was revealed that Au nanoparticles play a key role in enhancing the performance of the hybrid photo detectors.