Large Electro-optic Activity and Enhanced Thermal Stability from Diarylaminophenyl-Containing High-β Nonlinear Optical Chromophores

Abstract

Two series of highly efficient and thermally stable nonlinear optical chromophores based on the (4-diarylamino)phenyl electron donors have been synthesized and systematically investigated. A modular approach has been employed to synthesize these electron donors with tunable size, shape, and electron-donating abilities. Efficient conjugated bridges were extended from these donors and coupled with very strong CF3−TCF electron acceptors to afford chromophores with very high β values (up to 7077 × 10-30 esu at 1.907 μm). These chromophores possess much higher thermal stability (with their onset decomposition temperatures all above 220 °C) than those substituted with (4-dialkylamino)phenyl donors. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into very large electro-optic (E-O) coefficients (r33) in poled polymers through suitable shape engineering. Exemplified by the chromophore B4, which has a fluorinated aromatic substituent anchored at its donor end, it showed a very large r33 (169 pm/V) at 1.31 μm. This value is almost 1 order higher than the E-O activities usually reported for (4-diarylamino)phenyl-substituted NLO chromophores.