Thieno [2,3-b] indole-based second-order nonlinear optical chromophores with high thermal stability and good nonlinear optical performance

Abstract Tow novel second-order nonlinear optical (NLO) chromophores A4, A5 containing the thieno [2,3-b] indole (TI) group as a novel electron-donor, ethylene as a p-conjugated bridge and malononitrile, 2-(3-cyano-4-methyl-5-phenyl-5-(trifluoromethyl) furan-2 (5H)-ylidene) malononitrile (CF3-TCF) as the acceptor have been synthesized and systematically investigated in this paper. These TI-based chromophores showed significantly high thermal stability. The UV–vis spectra indicated that the TI-based chromophores had a red-shift compared to the carbazole-based chromophores both in solid state and in solution. The HOMO-LUMO energy gaps and hyperpolarizability (β) of the chromophore A5 is calculated by Density functional theory (DFT), it shows that A5 has a narrow energy gap and big β. In short, the TI-based chromophore A5 we synthesized exhibited high thermal stability and good NLO activity.