Visible-blind UV photodetectors using a polymer/ZnO nanocomposite thin film

Abstract

We report the fabrication and characterization of visible-blind UV photodetectors using thin films of polymer/zinc oxide (ZnO) nanocomposites. Polymer-ZnO nanocomposites based on three polymers, poly(methyl methacrylate)(PMMA), polystyrene(PS) and poly(vinylidene difluoride-trifluoroethylene(P(VDF-TrFE)) were studied. The electrical response of the detectors to 365 nm and 254 nm UV light illumination was probed. P(VDF-TrFE)/ZnO nanocomposite-based device exhibited the best performance compared to the other devices, possibly due to its ferroelectric property. Further, we prepared P(VDF-TrFE)/ZnO nanocomposite with different wt% of ZnO nanoparticles and characterized them by atomic force microscopy (AFM), X-ray diffraction (XRD), fourier transform- infrared spectroscopy (FTIR), UV-Visible absorption spectroscopy, and Photoluminescence (PL). XRD and FTIR studies confirmed the formation of the β phase of P(VDF-TrFE) in pristine polymer films and their nanocomposites. The influence of the top electrode material on the photodetector performance of nanocomposites was studied. P(VDF-TrFE)/5 wt% ZnO nanocomposite with Ag top electrode exhibited the best performance with on-off ratio, 1.4 × 104; responsivity, 14.43 A/W; linear dynamic range, 83.09 dB and detectivity, 2.27 × 1013 jones under 365 nm light illumination. The ferroelectric polarization mechanism of P(VDF-TrFE) and the choice of electrode play an important role in the performance of the devices.