Optical Spectra of Organic Dyes in Condensed Phases: the Role of the Medium Polarizability

When designing molecular functional materials, the properties of the active specie, the dye, must be optimized fully accounting for the presence of a surrounding medium (a solvent, a polymeric matrix, etc.) that may largely alter the dye behavior. Here we present an effective model to account for the effects of the medium electronic polarizability on the spectral properties of charge-transfer dyes. Different classes of molecules are considered and the proposed antiadiabatic approach to solvation is contrasted with the adiabatic approach, currently adopted in all quantum chemical approaches to solvation. Transition frequencies and band-shapes are addressed, and the role of the medium polarizability on symmetry-breaking phenomena is also discussed.