New ultraviolet photodetector based on individual Nb₂O ₅ nanobelts

Although human eyes are quite insensitive to ultraviolet (UV) light, most of the longer wavelength UV light (the UV-A band between 320 and 400 nm) does reach the earth surface and after prolonged exposure, the radiation can cause health concerns especially skin cancer. Therefore, it is extremely important to explore ways to effectively monitor the radiation. Herein we report for the first time a new high-performance UV photodetector made of an individual Nb ₂O₅ nanobelt. Quasi-aligned Nb₂O₅ nanobelts 100-500 nm wide and 2-10 μm long were synthesized using a hydrothermal treatment of a niobium foil in a KOH solution followed by proton exchange and calcination treatment. A nanostructured photodetector was constructed from an individual Nb₂O₅ nanobelt and its optoelectronic properties were evaluated. The detector exhibited linear photocurrent characteristics, excellent light selectivity, and high external quantum-efficiency (EQE) of 6070%. Long-term stability of the photocurrent over a period of 2500 s at an applied voltage of 1.0 V was achieved. The photodetector performance was further enhanced by improving the crystallinity and eliminating the defects in the Nb₂O₅ nanobelt crystals. These excellent optoelectronic properties demonstrate that Nb ₂O₅ nanobelts are suitable for visible-blind UV-light sensors and optoelectronic circuits, especially those operating in the UV-A range. A new and high-performance ultraviolet photodetector was successfully constructed from an individual Nb₂O₅ nanobelt for the first time. The as-constructed photodetector exhibited a high photosensitivity, light selectivity, excellent photocurrent stability, and high external quantum efficiency (6070%), demonstrating that Nb₂O₅ nanobelts is a perfect candidate for visible-blind ultraviolet-light sensors, especially for working in the UV-A band. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.