A high responsivity UV - visible dual band photodetector based on SnO2 microwires with RhB surface sensitization

Abstract

A SnO2 microwire (MW) based dual band photoconductive photodetector without persistent photoconductivity has been achieved. For expansion of the photo response to visible light, a dual band photodetector with UV and visible light response was fabricated via introducing RhB dye molecules. Due to the surface sensitization, photo responsivity of 43.1 A W−1 was obtained under 520 nm light illumination and 10 V bias for the detector made from a dye modified SnO2 MW, which is a 7-fold increase when compared to a photodetector fabricated from sole SnO2 MW (about 5.3 A W−1). The dual band photodetector also showed about double responsivity at 260 nm (about 351.9 A W−1) when compared to the detector made from sole SnO2 MW (about 183.9 A W−1), indicating improved UV light detection. Furthermore, under light excitations at 260 nm and 550 nm, the detectivity of about 2.38 × 1011 Jones and 3.55 × 1010 Jones can be obtained respectively for RhB molecule surface sensitized SnO2 MW at 10 V bias voltage. Through comparison of the electronic structures, the improved device performance in UV and visible light are attributed to the electron transfer mechanism from RhB to SnO2 surface, which can be verified from the measured I - t curves.