Unique Metal Dicorrole Dyes with Excellent Photoelectronic Properties for Solar Cells: Insight from Density Functional Calculations

A new type of metal dicorrole dyes has been designed, and their optical and electronic properties have been characterized by density functional, calculations. These novel dicorrole-based sensitizers have a strong light-harvesting ability and an excellent charge separation in the excited states. Their optical and electronic properties can be well-modulated by incorporating the bridge-conjugated group. Introduction of the electron-withdrawing substituent to the meso position of corrole ring regulates the energy levels of key molecular orbitals in the metal-dicorrole dyes to facilitate the regeneration of the oxidized dyes. Calculations show that the metal-dicorrole sensitizers are quite promising for fabrication of the high-performance dye-sensitized solar cells. On the basis of the first-principles calculations, plausible mechanisms for direct and indirect electron injections from the adsorbed dye to TiO2 have been discussed.