title: Novel UV-Visible Photodetector in Photovoltaic Mode with Fast Response and Ultrahigh Photosensitivity Employing Se/TiO2Nanotubes Heterojunction.
abstract: A feasible strategy for hybrid photodetector by integrating an array of self-ordered TiO2nanotubes (NTs) and selenium is demonstrated to break the compromise between the responsivity and response speed. Novel heterojunction between the TiO2NTs and Se in combination with the surface trap states at TiO2help regulate the electron transport and facilitate the separation of photogenerated electron-hole pairs under photovoltaic mode (at zero bias), leading to a high responsivity of ≈100 mA W-1at 620 nm light illumination and the ultrashort rise/decay time (1.4/7.8 ms). The implanting of intrinsic p-type Se into TiO2NTs broadens the detection range to UV-visible (280-700 nm) with a large detectivity of over 1012Jones and a high linear dynamic range of over 80 dB. In addition, a maximum photocurrent of ≈107A is achieved at 450 nm light illumination and an ultrahigh photosensitivity (on/off ratio up to 104) under zero bias upon UV and visible light illumination is readily achieved. The concept of employing novel heterojunction geometry holds great potential to pave a new way to realize high performance and energy-efficient optoelectronic devices for practical applications.
authors.affiliation: Department of Materials Science, Fudan University, Shanghai, 200433, P. R. China.
authors.forename: Lingxia
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Department of Materials Science, Fudan University, Shanghai, 200433, P. R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Hu
authors.affiliation: Department of Materials Science, Fudan University, Shanghai, 200433, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Teng
authors.affiliation: Department of Materials Science, Fudan University, Shanghai, 200433, P. R. China.
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Fang
keywords: TiO2 nanotubes; heterojunctions; photosensitivity; selenium; self-powered photodetectors