Effect of dye-semiconductor electronic coupling on solar energy conversion efficiency in dye sensitized solar cells

Dye sensitized solar cells have proven a promising approach for solar energy conversion. Optimization of overall efficiency has primarily focused on modification of dye absorption/spectral coverage, electrodes, and electrolyte composition. An important remaining issue is how the absorbed-photon-to-current efficiency (APCE) is effected by the dye-semiconductor electronic coupling. This coupling may be significantly dependent upon the linker, which serves to both anchor the dye to the surface and also mediates the electron transfer. This work focuses on the effect of structural modification of the linker group on charge injection and therefore the solar to electrical energy conversion efficiency. The role of frontier orbital energy levels, orbital geometry, and dye substitution pattern (meso or beta positions) is probed to understand the role of electronic coupling and subsequently any effect on efficiency.