ZnO nanoneedle/H2O solid-liquid heterojunction-based self-powered ultraviolet detector

Abstract

ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode.

ZnO/CuCrO2 Core–Shell Nanowire Heterostructures for Self‐Powered UV Photodetectors with Fast Response

“…A promising path for the fabrication of self‐powered UV photodetectors is to use the internal built‐in potential difference of a p–n heterojunction at zero bias to prevent the recombination of photogenerated electron–hole pairs, thereby maximizing available photocurrent . Other strategies include photo‐electrochemical cells and Schottky metal semiconductor heterojunctions . Self‐powered UV photodetectors made of ZnO NW heterostructures in combination with wide bandgap inorganic semiconductors, such as p‐type GaN, NiO, CuSCN, and n‐type Ga 2 O 3 , as well as with p‐type organic semiconductors such as 2,2′,7,7′‐Tetrakis‐( N , N ‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (Spiro‐MeOTAD) have already been reported.…”

The enhancement of a self-powered UV photodetector based on vertically aligned Ag-modified ZnO nanowires

“…1,2 Especially, ZnO nanowires (NWs), with a high aspect ratio, provide not only a large surface area for charge transfer but also a long pathway for light absorption in terms of the optoelectronic applications in the near UV-wavelength regions, which makes it a promising material for UV detectors. 12,13 This sandwich-like structure resembles a conventional dye-sensitized solar cell but without dye absorption. 5,[8][9][10][11] However, in order to full high photosensitivity, rigid epitaxial processes and single-crystal substrates are needed, which lead to high production cost.…”

“…[3][4][5][6][7] Up to now, various UV detectors based on ZnO have been reported such as metal-semiconductor-metal, p-i-n, p-n junction, or Schottky barrier planar-type structures. 12,14 However, the conducted photocurrent and photoresponsivity are still low. 4 Recently, an emerging self-powered UV detector based on a ZnO/water solid-liquid heterojunction (SLHJ) exhibits a practical UV detecting performance, which is constructed without complicated epitaxial process.…”

“…12 Here the Pt serves as both a catalyst for the redox reaction and conducting road for the electrons. Aerwards, a space charge layer is produced, owing to the difference of the charge distribution from the material.…”

Self-powered solid-state photodetector based on TiO2 nanorod/spiro-MeOTAD heterojunction

“…Self-powered photodetectors have attracted lots of attention due to their various advantages, including high photosensitivity, fast time response, good photosensitivity linearity in a wide light intensity range, low-cost, and energy saving. [13][14][15][16][17] Converting energy from the environment directly into use makes self-powered device one of the most effective and promising superiority for commercially integrated photoelectronic application. 18 P-n junction is one of the best choices to realize selfpowered photodetectors, in which the large built-in electric field will separate the photogenerated electrons and holes.…”