Improved sensitivity of UV sensors in hierarchically structured arraysof network-loaded ZnO nanorods via optimization techniques

Hierarchical nanostructures have received much attention in recent years for their enhanced fundamental properties and potential applications in manifold areas. Herein, we report a simple and robust strategy for the fabrication of hierarchically nanostructured arrays of network-loaded ZnO nanorods (NRs) for use in UV photodetectors based on comprehensively optimized experimental conditions using the Taguchi approach. Specifically, the critical roles of the morphological and structural characteristics of ZnO NRs on the UV sensing properties are systematically evaluated. Results show that the specific deposition conditions of the secondary colloidal ZnO NRs onto the surface of the vertically grown ZnO NRs contribute to the formation of tightly organized networks over large areas, which act as favorable energy junction barriers, and thus play a significant role in enhancing the performance of the UV photodetector. Under optimal conditions, the sensitivity of the prepared UV sensors was improved to 8000, which has not been reported yet in the field of ZnO-based UV sensors with vertical networked nanostructures. Our comprehensive studies to optimize sensitivity, responsivity, and response/recovery times suggest a highly viable route for practical applications in photodetectors using this facile implementation of ZnO NRs.