Thursday, July 30, 2015

Abstract-Functioning Photoelectrochemical Devices Studied with Time-Resolved Terahertz Spectroscopy

J. Phys. Chem. Lett., Just Accepted Manuscript
DOI: 10.1021/acs.jpclett.5b01473
Publication Date (Web): July 29, 2015
Copyright © 2015 American Chemical Society


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 non-conducting 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 THz through patterned electrodes (15 μm wire width and 20 μm 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 the 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 bias voltage is increased.

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