Enhanced performance of dye-sensitized solar cells by co-sensitization of metal-complex and organic dye

Abstract

We systematically investigated a co-sensitized dye comprising of the Ru-complex (N719) dye blended with organic (Coomassie brilliant-blue R-250) as a novel photosensitizer for application in dye-sensitized solar cells (DSSCs). Compared with DSSCs made with the individual dyes, the power conversion efficiency of DSSC with co-sensitized dye is increased by 22 %, i.e., from 9.07 to 11 %. This enhancement results mainly from the significant increase in the open-circuit voltage (VOC) upon co-sensitization due to the upward movement of the conduction band edge and reduction in the charge recombination. Impedance spectroscopy analysis reveals higher charge recombination resistance and greater carrier lifetime for the co-sensitized dye-based DSSC, suggesting that the suppressed recombination due to improved morphology and reduced defects yields a high VOC. Moreover, co-sensitized DSSC exhibited enhanced short circuit current (JSC) and fill factor (FF). This strategy of using a co-sensitized dye as a photosensitizer in DSSCs could pave an effective way to approach high-performance, cost-effective DSSCs.