Stepwise cosensitization for high efficiency dye-sensitized solar cells utilizing solid-state polymer electrolytes

Mesoporous TiO₂ surface engineering is a field to be still advanced toward highly efficient dye-sensitized solar cells (DSCs) utilizing solid-state polymer electrolytes. Herein, a facile and stepwise cosensitization method is applied for ruthenium C106 dye and organic D131 dye. After the C106 dyes were adsorbed, D131 dyes were subsequently coadsorbed onto empty sites of the mesoporous TiO₂ surface without desorption of the C106 dyes, and their amount was controlled by varying the concentration of the D131 dye solution. At the optimal concentration of the D131 dye solution, a remarkable energy conversion efficiency of 8.4% was attained under 1 sun illumination conditions, as a result of a noticeable rise in photocurrent density. According to the photovoltaic characterization, both the light harvesting and the charge collection efficiencies for DSCs prepared by the stepwise cosensitization process were greatly superior to those of individual C106 or D131 dyes.