Enhanced Incident Photon-to-Electron Conversion Efficiency of Tungsten Trioxide Photoanodes Based on 3D-Photonic Crystal Design

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• 作者：Xiaoqing Chen ; Jinhua Ye ; Shuxin Ouyang ; Tetsuya Kako ; Zhaosheng Li ; Zhigang Zou
• 刊名：ACS Nano
• 出版年：2011
• 出版时间：June 28, 2011
• 年：2011
• 卷：5
• 期：6
• 页码：4310-4318
• 全文大小：1118K
• 年卷期：0
• ISSN：1936-086X

文摘

In this study, 3D-photonic crystal design was utilized to enhance incident photon-to-electron conversion efficiency (IPCE) of WO₃ photoanodes. Large-area and high-quality WO₃ photonic crystal photoanodes with inverse opal structure were prepared. The photonic stop-bands of these WO₃ photoanodes were tuned experimentally by variation of the pore size of inverse opal structures. It was found that when the red-edge of the photonic stop-band of WO₃ inverse opals overlapped with the WO₃ electronic absorption edge at E_g = 2.6–2.8 eV, a maximum of 100% increase in photocurrent intensity was observed under visible light irradiation (λ > 400 nm) in comparison with a disordered porous WO₃ photoanode. When the red-edge of the stop-band was tuned well within the electronic absorption range of WO₃, noticeable but less amplitude of enhancement in the photocurrent intensity was observed. It was further shown that the spectral region with a selective IPCE enhancement of the WO₃ inverse opals exhibited a blue-shift in wavelength under off-normal incidence of light, in agreement with the calculated stop-band edge locations. The enhancement could be attributed to a longer photon–matter interaction length as a result of the slow-light effect at the photonic stop-band edge, thus leading to a remarkable improvement in the light-harvesting efficiency. The present method can provide a potential and promising approach to effectively utilize solar energy in visible-light-responsive photoanodes.