Dye sensitization of nanocrystalline TiO2: enhanced efficiency of unsymmetrical versus symmetrical squaraine dyes

A series of novel symmetrical and unsymmetrical squaraine dyes have been synthesized and their comparative efficiencies as photosensitizers in dye sensitized solar cells (DSSCs) containing nanocrystalline TiO 2 photoelectrodes have been investigated. DSSCs employing unsymmetrical squaraines as sensitizers produced photocurrent with much higher efficiencies compared to DSSCs containing symmetrical squaraines. Aggregation of the dyes on the TiO 2 nanocrystalline electrode was observed to adversely affect the sensitization properties of symmetrical squaraines, whereas efficient sensitization was observed from both the monomeric and aggregated forms of the unsymmetrical squaraines.

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