Charge transfer mechanism in dye-sensitized solar cells

Outline of Final Research Achievements

Dye-sensitized solar cells (DSCs) consist of a metal oxide electrode, organic dyes, and an electrolyte solution. Under light irradiation, photo-excited electrons in the dyes are injected into the oxides, and oxidized dyes are reduced by redox couples in the electrolyte solution. For the charge separation, present DSCs lose a lot of energy. The aim of this study is to elucidate the charge separation mechanism and to propose dye structures minimizing the energy loss. Along the aim, we designed and synthesized several series of dyes whose structures were systematically varied. Charge transfer kinetics of DSCs employing these dyes was measured. We found that the physical size of donor moiety, conjugation length, and location of partial charges of dyes influenced the kinetics significantly. The effect of adsorption angle was different from intuitive hypothesis. Based on these, we discussed the dye structures for highly efficient DSCs.