Selective sensitization strategy for high-performance panchromatic dye-sensitized solar cells incorporated with ruthenium-based double dyes

Abstract

To facilitate the assembly of high-performance panchromatic dye-sensitized solar cells (DSSCs), it is important to determine the selection and sensitization of dyes in photoelectrodes. This paper reports the fabrication of panchromatic DSSCs comprising freestanding and fixed TiO2 thin films (TFs). These TFs constitute a bilayered photoelectrode coated with ruthenium-based double dyes. In addition, we systematically examine the effect of the separated sensitization of double dyes on DSSC performance. The UV–vis spectroscope measurements reveal that the ruthenium-based dyes exhibit light-absorbance values in the order of C106 > N719 > N749. The results of the separated sensitization of C106 (bottom layer)/N719 (top layer) dyes reveal a maximum efficiency of 8.10 %. Correspondingly, the separated sensitization of N749/N719 dyes yields a poor PCE of 5.85 %. In addition, the mixed sensitization of the double dyes (i.e., C106 + N719, C106 + N749, and N719 + N749) is found to demonstrate poor DSSC performance compared to the corresponding separated sensitization (i.e., C016/N719, C106/N749, and N719/N749). This can be attributed to the occurrence of negative interactions between mixed dyes. Therefore, to improve the panchromatic DSSC performance, it is suggested that dyes with high and low light-absorbance values be sensitized on the bottom and top layers, respectively.