| Abstract
| - This paper reports a new coumarin dye, 2-cyano-3-(5-{2-[5-(1,1,6,6-tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de]anthracen -9-yl)-thiophen-2-yl]-vinyl}-thiophen-2-yl)-acrylic acid (NKX-2700), and its application in dye-sensitized solar cells (DSSCs). Under illumination of simulated AM1.5Gsolar light (100 mW cm-2) with an aperture black mask, 5.0% of power conversion efficiency [short-circuitphotocurrent density (Jsc) = 12.0 mA cm-2, open-circuit photovoltage (Voc) = 0.59 V, and fill factor (FF) =0.71] was obtained for NKX-2700 based DSSC, which was significantly improved to 8.2% (Jsc = 15.9 mAcm-2, Voc = 0.69 V, FF = 0.75) upon addition of 120 mM deoxycholic acid (DCA) to the dye solution forTiO2 sensitization. Coadsorption of DCA decreased dye coverage by ∼50% but significantly improved theJsc by 33%. The breakup of π-stacked aggregates might improve electron injection yield and thus Jsc.Electrochemical impedance data indicate that the electron lifetime was improved by coadsorption of DCA,accounting for the significant improvement of Voc. These results suggest that interfacial engineering of theorganic dye-sensitized TiO2 electrodes is important for highly efficient photovoltaic performance of the solarcell.
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