Enhanced electro-optic activity and thermal stability by introducing rigid steric hindrance groups into double-donor chromophore

A series of novel chromophores based on same bis (N,N-diethyl) aniline donor have been synthesized and systematically characterized. Chromophores with rigid steric hindrance groups showed superb thermal stabilities with high thermal decomposition temperatures above 260 °C. Besides, compared with the chromophore (y2) without isolation group, these new chromophores show better intramolecular charge-transfer absorption. Most importantly, the introduction of rigid steric hindrance groups can effectively reduce dipole–dipole interactions to translate their relatively β values into bulk large electro-optic activities. The electro-optic coefficient of poled films containing 25 wt % of these new chromophores doped in amorphous polycarbonate afforded values of 163, 129, 183 and 196 pm V−1 at 1310 nm for chromophores y1-y4 respectively. These results indicated that introducing rigid isolation group to control the shape of chromophores can efficiently reduce intermolecular electrostatic interactions, thus enhancing the macroscopic electro-optic activity. These properties, together with good solubility, suggest the potential use of these chromophores as advanced material devices.