Functioning Photoelectrochemical Devices Studied with Time-Resolved Terahertz Spectroscopy

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• 作者：Coleen T. Nemes ; Christopher Koenigsmann ; Charles A. Schmuttenmaer
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：August 20, 2015
• 年：2015
• 卷：6
• 期：16
• 页码：3257-3262
• 全文大小：372K
• ISSN：1948-7185

文摘

Terahertz (THz) spectroscopy has been used over the years to study carrier dynamics in a large variety of semiconductor materials utilized in devices such as photoelectrochemical cells. However, due to low transmission of far-infrared radiation through conductive films, thin layers of material deposited on nonconducting substrates have been investigated rather than inside actual devices. Here, we photolithographically etch fluorine-doped tin oxide (FTO) coatings to produce a pattern analogous to a wire-grid THz polarizer, and measure a nearly 260-fold increase in percent power transmitted at 1聽THz through patterned electrodes (15 渭m wire width and 20 渭m wire period) relative to continuous FTO films. We have employed them as visible and THz-transparent electrodes in dye-sensitized solar cells, thereby enabling us to probe the carrier dynamics of a functioning device under an applied bias and with background illumination using time-resolved THz spectroscopy. We find that the electron injection efficiency and carrier trapping time both increase as the magnitude of the negative bias voltage is increased.