Synthesis and characterization of novel electro-optic chromophores based on 4-hydroxycarbazole

Two novel nonlinear optical (NLO) chromophores with 4-hydroxycarbazole as the electron donor were successfully designed and synthesized. The 4-hydroxycarbazole had two reaction sites where the isolated groups were introduced to the chromophores. The prepared chromophores were characterized by MS, 1H NMR and UV–vis spectra. Poled films of the chromophores doped in APC afforded the maximum electro-optic (EO) coefficient (r33) of 40 pm/V at 1310 nm. This result was better than the similar chromophores reported using carbazole and aniline derivates as electron donor, which indicated that the introduction of isolated groups suppressed the dipole–dipole interaction between chromophores effectively and could aid the alignment of chromophores and improve the EO activity. This had been further demonstrated by the crystal structure analysis.

► Two novel chromophores are successfully designed and synthesized.
► Introduction of isolated groups effectively suppressed the dipole–dipole interaction.
► The maximum r33 value of 40 pm/V at 1310 nm was obtained by corona poling.