Intermittent light studies to investigate electron mobility in dye-sensitized solar cells.

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Date: Jan. 1, 2021
From: Solar Energy(Vol. 213)
Publisher: Elsevier Science Publishers
Document Type: Brief article
Length: 305 words

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Abstract :

Highlights * An intermittent light study explores time-dependent photocurrent. * Validation of electron hopping electron diffusion. * Varying illumination and dark times lead to different electron diffusion kinetics. * Trapped electrons can persist for seconds to tens of seconds. Abstract Dye sensitized solar cells can be constructed out of inexpensive materials such as titanium dioxide and the anthocyanin dye from raspberries but have shown efficiency issues related to the diffusion of electrons. Intermittent light studies were used to characterize the time-dependent photocurrent decay and growth after a shutter was either closed or opened, respectively, to gain insight on how photoinjected electrons diffuse through these semiconductor films. The data was fit with a biexponential decay or growth model, and significant differences were seen between devices with and without lithium ions in the electrolyte solution as well as a hysteresis depending on how long the device was under illumination or in the dark. We found that for both the photocurrent growths and decays, the faster lifetime component had a larger relative population. For both the decay and growth, the lifetime of the faster component did not have a significant difference when lithium perchlorate was added to the electrolyte solution. However, the presence of the lithium increased the lifetime of the slower component in both the growth curves and the decay curves. When comparing the data for devices that had a 10-second on/off cycle compared to a 1-minute on/off cycle, both the longer and the shorter lifetime components are shorter for the 10-second cycles. These results support the electron hopping model where electrons must diffuse through a dispersive energetic landscape. Author Affiliation: Bridgewater College, Bridgewater, VA 22812, United States * Corresponding author. Article History: Received 15 July 2020; Revised 24 October 2020; Accepted 1 November 2020 Byline: Cheyenne S. Mitchell, Gabrielle M. Perkins, Ian J. McNeil [imcneil@bridgewater.edu] (*)

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Gale Document Number: GALE|A648932511