Novel chromophores with excellent electro-optic activity based on double-donor chromophores by optimizing thiophene bridges

Abstract

Three novel nonlinear optical chromophores based on the same bis(N,N-diethyl)aniline donor have been synthesized and systematically characterized. These chromophores showed good thermal stability and chromophore y1 showed the best thermal stability of 249 °C. Besides, compared with the chromophore (y1) without the substituted group, chromophores y2 and y3 show better intramolecular charge-transfer absorption. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic coefficients. The electro-optic coefficient of poled films containing 25% wt of chromophores y1–y3 doped in amorphous polycarbonate afforded values of 149, 138 and 157 pm/V at 1310 nm for chromophores y1–y3 respectively. These results indicated that the double donors of bis(N,N-diethyl)aniline unit can efficiently improve the electron-donating ability and the special structure can 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 materials.