Diketopyrrolopyrrole-based sensitizers for dye-sensitized solar cell applications: anchor engineering

A series of donor-chromophore-anchor (D-C-A) sensitizers comprising the diketopyrrolopyrrole (DPP) chromophore were synthesized and tested in both I-3(-)/I- and Co(bpy) redox shuttle DSC devices. The dye series was strategically designed to elucidate structure-property relationships, concerning overall performance and compatibility with these two electrolytes. Selective fluorine incorporation improved I-3(-)/I--based DSC performance, while hindering performance with the positively charged cobalt-based redox shuttle. Incorporation of a pyridine heterocycle into the DPP chromophore increased spectral breadth, but decreased performance metrics for both electrolyte systems. These results are understood through detailed electrochemical, photophysical, and computational studies.