TD-DFT approach has been employed to investigate effect of two ionic additives namely Lithium bis (trifluoromethylsulfonyl) imide (Li-TFSI) and 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIM-TFSI) in the solid state Dye-sensitized Solar Cells (ssDSSCs) comprised of D102 dye and TiO2 metaloxide. Although these additives have been reported to improve the cell performance, the exact role of them is not yet established. It has been reported previously that the presence of Li-TFSI leads to an adsorption of Li+ ions on TiO2 surface. This causes a change in surface potential and shift of conduction band (CB) edge of titania to the lower energy. Due to this shift in the CB edge, more density of states (DOS) becomes available for a fast intermolecular charge transfer (CT). Contrary to this, EMIM-TFSI does not affect the TiO2 surface potential but still shows improvement in photocurrent conversion efficiency of the ssDSSCs. Therefore to gain insight on the effect of these additives in the photochemical properties of ssDSSCs, we have performed a detailed TD-DFT study on these systems, comparing our electronic structure and spectroscopic results to available experimental information.

First principle approach to study role of ionic additives in the solid-state dye-sensitized solar cells

245th National Meeting (2013)

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