Nanostructured TiO2 semiconductor electrodes modified with surface-attached viologens: applications for displays and smart windows

Anders Hagfeldt; Lorenz Walder; Michael Graetzel

doi:10.1117/12.217359

23 August 1995 Nanostructured TiO₂ semiconductor electrodes modified with surface-attached viologens: applications for displays and smart windows

Anders Hagfeldt, Lorenz Walder, Michael Graetzel

Author Affiliations +

Proceedings Volume 2531, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV; (1995) https://doi.org/10.1117/12.217359
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Viologen derivatives adsorbed on TiO₂ surfaces in nanocrystalline-nanoporous electrodes have been studied with respect to electrochromic phenomena. The transparent nature and the high internal surface area of these electrodes are very beneficial for this purpose. Two different viologens were studied giving rise to blue, green, and violet coloration. For one of the viologens we show the possibility to vary the color for the same viologen/TiO₂ electrode from transparent to green or violet depending on the applied potential. Depending on the applied potential different optical densities were obtained. Optical density changes from 0.1 up to 1 and coloration efficiencies above 100 cm²C^-1, with a maximum value of 440 cm²C^-1, were obtained. The switching times for these electrodes for both coloration and bleaching were faster than 1s for a transmittance change larger than 60%, using 0.5M LiClO₄ in acetonitrile as electrolyte. Preliminary stability tests were performed. One electrode has been cycled 654 times without substantial decline in coloration efficiency.

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Anders Hagfeldt, Lorenz Walder, and Michael Graetzel "Nanostructured TiO₂ semiconductor electrodes modified with surface-attached viologens: applications for displays and smart windows", Proc. SPIE 2531, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV, (23 August 1995); https://doi.org/10.1117/12.217359

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