A combined experimental and theoretical study of natural betalain pigments used in dye-sensitized solar cells
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- 作者：Corneliu I. Oprea ; Anca Dumbrav? ; Irina Enache ; Adrian Georgescu ; Mihai A. G?r?u
- 关键词：Dye-sensitized solar cells ; Betalains ; Nanocrystalline TiO2 ; Photovoltaic conversion efficiency ; Time-dependent density functional theory ; Optical spectra
- 刊名：Journal of Photochemistry and Photobiology A: Chemistry
- 出版年：2012
- 出版时间：15 July, 2012
- 年：2012
- 卷：240
- 期：Complete
- 页码：5-13
- 全文大小：1187 K
文摘
We report results of combined experimental and theoretical studies of betalain natural dyes used as sensitizers for TiO2 dye-sensitized solar cells (DSSCs). To analyze the compliance of the various forms of betalain dyes with the main criteria that should be met by a dye to be used as TiO2 sensitizer in a DSSCs, we performed density functional theory (DFT) calculations, which provided the optimized geometry, electronic structure and electronic spectrum of the dyes in fully protonated as well as partially deprotonated forms, in solution. We discuss the adsorption onto the substrate, the matching of the absorption spectrum of the dye with the solar spectrum, the energy level alignment with the semiconductor and the electrolyte, and the charge transfer to the substrate. By comparing the theoretical results with the experimental data we identify the betacyanins as the useful constituents of the betalain extracts and emphasize the role of extract purification.