Hybrid-Organic-Photodetector Containing Chemically Treated ZnMgO Layer With Promising and Reliable Detectivity, Responsivity and Low Dark Current

摘要

The glass/ITO/ZnO/ZnMgO/PEOz/PCBM/P3HT: PCBM/CH3-SAM/PEDOT: PSS/Ag structure is used to fabricate a hybrid organic photodetector (HOP). The device operates with an optimized detectivity of 4.8 x 10(14) Hz(1/2)/W and a responsivity of 2.63 x 10(2)A/W. ZnMgO nanorods, mostly textured (with (002) orientation) and with hexagonal morphology, are made using a post-thin-film-deposition chemo-thermal process. This process helps in passivation of trap states in ZnO. The device structure reported aids in: 1) obtaining a promising broadband UV photoresponse and 2) improvement in charge collection efficiency (J(sc)similar to 120 mA/cm(2)). J(sc) obtained in this device is similar to 30 times higher than the samples that only use ZnO nanorods. The photocurrent decay is dominated by a slow process with a characteristic decay time of 198 mu s. This is attributable to the presence of deep traps (less density of free carriers than a large density of trap states), indicating that the defect states in ZnO are not completely eliminated even with the chemothermal passivation step used. The PEOz and CH3-SAM layers in the device contribute to a reduction in dark current, and an improvement in spectral response. The results presented here are of direct relevance to the current state of the-art in UV-HOP devices.