Density functional theory investigation of the electronic and optical properties of metallo-phthalocyanine derivatives

The electronic and optical properties of metallo-phthalocyanine derivatives have been calculated by using density functional theory. Starting from a reference Zn(II) phthalocyanine the structure has been varied by changing the nature of the transition metal, by adding carboxylic functions, as well as by considering the extension of the aromatic rings with fused phenyl moieties, with the perspective of optimizing their performance as sensitizers in solar cells. Calculations demonstrate that the transition metal (Ni, Mn, Fe, Co, and Cu versus Zn) has a small impact on the free energies of the primary processes (injection, recombination, and regeneration), that adding several carboxylic acid functions has a cooperative role to optimize the injection process, and that the addition of fused phenyl rings increases the light harvesting efficiency and the free energy of injection.