Gold nanoparticle-embedded DNA thin films for ultraviolet photodetectors

Although DNA (low-cost, highly transparent, low optical loss, biodegradable, non-toxic, and highly flexible) and gold nanoparticles (Au NPs, exhibiting interband transition and localized surface plasmon resonance) have been intensively studied, DNA with Au NPs in photodetectors is rarely discussed. Here, we constructed salmon DNA (SDNA) thin films and incorporated Au NPs to demonstrate efficient and high-performance UV photodetectors. The Au NP-embedded SDNA thin films were characterized with UV-vis absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and conductivity measurements in order to understand their physical and chemical properties. The FTIR and XPS measurements elucidated how Au NPs become embedded in SDNA, through analysis of chemical binding and chemical composition. A current increase was observed under UV illumination when performing conductivity measurements. In addition, photovoltage measurements were conducted to investigate the significance of photoresponse and retention characteristics. The density of d-band electrons in Au NPs and the charge carriers in SDNA were observed to increase under UV illumination, followed by a significantly enhanced UV photoresponse. From our observations, the photovoltage displayed a flat response over time, which indicated their stability, durability, and high Au NP retention.