Plasmon-enhanced all-organic ultraviolet photodetectors with high sensitivity and long-term stability

Abstract

All-organic ultraviolet (UV) photodetectors have gained significant attention due to their advantages of low-cost fabrication, flexibility, and ease of processing. However, challenges such as limited photoresponsivity, stability, and weak light detection have hindered their practical applications. In this study, we report the fabrication of Au nanoparticles (NPs) on ITO glass substrates via one-step annealing, followed by the construction of Au NPs/Ph-BTBT-12/C₆₀ UV photodetectors. The incorporation of Au NPs results in an absorption enhancement of approximately 443.2%, significantly improving the photoresponsivity performance of the device from 69.6 μA W⁻¹ to 413.1 μA W⁻¹. The device demonstrates photoresponsivity across the solar-blind UV spectrum and partial visible light, while efficiently detecting weak light at intensities as low as 0.01 mW cm⁻². Notably, the photodetector retains its performance after two months, exhibiting excellent stability. Finite element method simulations reveal that the different morphologies of the Au NPs lead to significant electric field enhancement. Furthermore, surface-enhanced Raman scattering (SERS) from the organic semiconductor C₆₀ was achieved by thermal annealing of the Au NP arrays. These findings offer valuable strategies for improving the performance and durability of organic UV photodetectors.