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

Qinghao Li1, Lin Wei2, Yanru Xie1, Kai Zhang1, Lei Liu1, Dapeng Zhu1, Jun Jiao34, Yanxue Chen1*, Shishen Yan1, Guolei Liu1 and Liangmo Mei1

Author Affiliations

1 School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People’s Republic of China

2 School of Information Science and Engineering, Shandong University, Jinan 250100, People’s Republic of China

3 Department of Mechanical and Materials Engineering, Portland State University, P.O. Box 751, Portland OR 97207-0751, USA

4 Department of Physics, Portland State University, P.O. Box 751, Portland OR 97207-0751, USA

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Nanoscale Research Letters 2013, 8:415  doi:10.1186/1556-276X-8-415

Published: 8 October 2013

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.

Keywords:
ZnO nanoneedle arrays; Hydrothermal method; Ultraviolet photodetector; Solid-liquid heterojunction