Abstract
A combined experimental (optical and electro‐optical absorption measurements) and computational (ab initio RHF and DFT) approach has been used to investigate the molecular low‐ and high‐T~g~ photorefractive (PR) performances of neutral and zwitterionic heteroaromatic dipolar chromophores in terms of structural and solvent‐polarity effects. We have found that the nature of the building units (donor, acceptor, and spacer) and the polarity of the surrounding medium strongly affect all the relevant ground‐state and nonlinear optical properties involved in the PR activity, that is, the dipole moment, the polarizability anisotropy, and first hyperpolarizability of the electronic ground‐state. The variation of these properties is in turn transferred to molecular low‐ and high‐T~g~ PR figures of merit. It is shown that PR molecular performance not only relies on a proper choice of structural components but varies by orders of magnitude as a function of the medium polarity, and this suggests that a combination of molecular design and host‐matrix engineering is required for optimized performances of PR materials.