We report a synthesis of single-crystal [001] oriented selenium nanobelts (SeNBs) through a simple vacuum evaporation at 250 C. The width and thickness of the SeNBs are in the range of 100-800 nm and 20-90 nm, respectively. I-V analysis of an individual SeNB based field effect transistor (FET) reveals typical p-type electrical conduction. The hole mobility and concentration are respectively estimated to 0.63 cm 2 (V s) À1 and 9.35 Â 10 16 cm À3 . The p-type electrical characteristics can be

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... ained by the surface termination model, according to which, H-or OH-termination can induce a defect level slightly above the valance band maximum (VBM). A fully transparent and flexible visible light photodetector assembled on a polyethylene terephthalate (PET) substrate shows a high sensitivity to visible light illumination, with sensitivity and conductive gain as high as 3.27 Â 10 4 A W À1 and 6.77 Â 10 4 respectively. Furthermore, the device also exhibits a stable performance and good reproducibility under different bending conditions. The high-performance visible light photodetector would enable application opportunities in future flexible and transparent electronics. Experimental Synthesis and characterization of SeNBs The fabrication of SeNBs was carried out in a tube furnace. Briefly, selenium powder (analytical grade, Sigma-Aldrich Co.)