Donor modification of nonlinear optical chromophores: Synthesis, characterization, and fine-tuning of chromophores' mobility and steric hindrance to achieve ultra large electro-optic coefficients in guest–host electro-optic materials

Abstract

We synthesized three new donor-modified push–pull chromophores with the same divinylenethiophenyl bridge and tricyanofuran acceptor, but with different modified donor moieties. Structure analysis and photophysical properties were carried out to compare the molecular mobility and steric hindrance effect of different donor-modified chromophores. Density functional theory calculations and thermal properties showed the different results of chromophores' microscopic nonlinearity and thermal stability. In electro-optic activities, the poling process demonstrated that guest–host electro-optic polymers containing the chromophores with different steric hindrance and molecular free mobility, required different optimal poling condition to achieve the large macroscopic electro-optic coefficients. After the exploration of the poling condition, it showed an ultra large electro-optic coefficient (266 pm/V) for electro-optic polymer WJ5-APC-2, which indicated the fine-tuning of steric hindrance and molecular free mobility of chromophore WJ5 in host polymer APC-2. Meanwhile, steric hindrance also improved the temporal stability of electro-optic coefficients for WJ5-APC-2.