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 TiO 2 have been discussed.