Spectroscopic evidences of synergistic co-sensitization in dye-sensitized solar cells via experimentation of mixture design

A systematic analysis for mixed dyes of D131, D149, and N3 ternary components on performance of dye-sensitized solar cells (DSSCs) has been performed. Using an experimental design of mixture, empirical models are fitted and plotted as contour diagrams, which facilitate revealing the synergistic/antagonistic effects between these mixed dyes. Dye co-sensitization effects in DSSCs are proved by the photo-physic properties, efficiency of the DSSC devices, and kinetic parameters of photo-electron transfer. The performance of DSSCs is significantly affected by the composition of dyes. The optimal efficiency (ca. 9.5%) of these mixed-dye DSSCs exists at the composition of 1/2 D149-1/2 N3. This composition appears to help conveying the charge transfer from the excited dye molecules to the conduction band of TiO2, leading to a higher efficiency of the assembled devices. Supplementary study of the electrochemical impedance are in support of enhancing charge transfer of TiO2 (e−) with the co-sensitized dyes.