Iodinated AlIII‐Based Phthalocyanines are Promising Sensitizers for Dye‐Sensitized Solar Cells; A Theoretical Comparison Between ZnII,MgII, and AlIII‐Based Phthalocyanine Sensitizers

To design efficient dyes for dye‐sensitized solar cells (DSSCs), using a Zn‐coordinated phthalocyanine (TT7) as the prototype, a series of phthalocyanine dyes (Pcs) with different metal ions and peripheral/axial groups have been investigated by means of density functional theory (DFT) and time‐dependent DFT (TDDFT) methods. Computational results show that the iodinated Al‐based dye with a peripheral amino group (Al‐I‐NH₂‐Pc) exhibits the largest redshift in the maximum absorbance (λ_max). In addition, Al‐based dyes have appropriate energy‐level arrangements of frontier orbitals to keep excellent balance between electron injection and regeneration of oxidized dyes. Further, it has been found that the intermolecular π‐staking interaction in Al‐I‐Pc molecules is weaker than the other metal‐based Pcs, which may effectively reduce dye aggregation on the semi‐conductor surface. All these results suggest iodinated Al‐based Pcs (Al‐I‐Pcs) to be potentially promising sensitizers in DSSCs.