Enhanced microscopic nonlinear optical properties of novel Y-type chromophores with dual electron donor groups

Highlights: • Novel Y-type NLO chromophores containing dual donor groups were synthesized. • 'Total charge transfer' from HOMO to LUMO of Y-type chromophores was discovered. • NLO properties of chromophores were enhanced due to efficient charge transfer. In this Letter, novel Y-type chromophores with dual electron donor groups, containing either styryl or azobenzene based π-conjugated bridge structures, were synthesized and their chemical structures, molecular configuration, microscopic optical properties as well as thermal properties were systematically characterized. The experimental results indicated that eight times increasing of second-order molecular hyperpolarizability as well as 50–100 nm blue shift of maximum absorption band for azobenzene based chromophore were observed by introducing Y-type dual electron donor groups, which was derived from the highly efficient 'total charge transfer' in this kind of chromophore as confirmed by the density functional theory calculation.