Chemical Tuning and Absorption Properties of Iridium Photosensitizers for Photocatalytic Applications

Cyclometalated Ir(III) complexes are of particular interest due to the wide tunability of their electronic structure via variation of their ligands. Here, a series of heteroleptic Ir-based photosensitizers with the general formula [Ir(CN)2(N ∧N)]+ has been studied theoretically by means of an optimally-tuned long-range separated density functional. Focusing on the steady-state absorption spectra, correlations between the chemical modification of both ligand types with the natures of the relevant dark and bright electronic states are revealed. Understanding such correlations builds up a basis for the rational design of efficient photocatalytic systems.