Drop‐cast and dye‐sensitized ZnO nanorod‐based visible‐light photodetectors

We report the facile fabrication of metal–semiconductor–metal (MSM) photodetectors with dye‐sensitized ZnO nanorods (NRs) operating at wavelengths of ～405–638 nm by a simple drop casting method. The ZnO NRs were synthesized by the hydrothermal synthesis method at 75 °C. The droplet of ethanol solution containing ZnO NRs was dropped between two metal electrodes and dried at 65 °C, which allows the ZnO NRs to be adhered and contacted to both metal electrodes. When a violet light of 405 nm was illuminated into the MSM ZnO NRs‐based photodetector, the photocurrent gain was obtained as ～3.9 × 10³ at the applied bias voltage of 5 V. By increasing the bias voltage from 10 V to 15 V, the device exhibited good recovery performance with a largely reduced reset time from 85.68 s to 2.47 s and an increased on–off ratio from 17.9 to 77.4. To extend the photodetection range towards the long visible spectral region, the ZnO NRs were sensitized by the N719 dye and then drop‐cast. The dye‐sensitized ZnO NRs‐based photodetector also exhibited good photocurrent switching under 638 nm of light illumination. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)