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

A SnO ₂ 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 SnO ₂ MW, which is a 7-fold increase when compared to a photodetector fabricated from sole SnO ₂ 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 SnO ₂ 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 × 10 ¹¹ Jones and 3.55 × 10 ¹⁰ Jones can be obtained respectively for RhB molecule surface sensitized SnO ₂ 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 SnO ₂ surface, which can be verified from the measured I - t curves.