Thiophene-Bridged Double D-π-A Dye for Efficient Dye-Sensitized Solar Cell

An organic dye containing two D-pi-A branches linked with a thiophene unit has been designed and synthesized for efficient dye-sensitized solar cells (DSSCs). As compared to the rod-shape of the single D-pi-A analogue dye, the cross shape of the double D-pi-A branched dye is favorable for reducing intermolecular interaction and retarding charge recombination. Controlled intensity modulated photovoltage spectroscopy reveals that electron lifetime for the double D-pi-A dye-based DSSC is 14-fold longer than that for the corresponding single D-pi-A dye-based DSSC. Linking two D-pi-A branches with a thiophene unit increases open-circuit photovoltage by 100 mV and short-circuit photocurrent by 4.10 mA cm(-2). As a consequence, power conversion efficiency is enhanced by about 2-fold. This work presents a new route to designing sensitizers with high suppression ability of charge recombination toward high-performance DSSCs.