Site-isolated electro-optic chromophores based on substituted 2,2′-bis(3,4-propylenedioxythiophene) π-conjugated bridges

Application of bis(propylenedioxythiophene) (bis(ProDOT)) pi-conjugated bridges bearing alkyl or aryl substituents in electro-optic (EO) chromophores is presented. A series of three bis (ProDOT)-based chromophores and a bithiophene-based control chromophore were prepared and fully characterized with regard to EO applications. The highly planar bis(ProDOT) bridge results in slightly larger (similar to 10%) molecular hyperpolarizability (beta) values as compared to the bithiophene bridge, as measured by hyper-Rayleigh scattering at a variety of wavelengths. In amorphous polycarbonate guest-host films, however, the bulky substituents on the bis(ProDOT) bridge result in significantly larger (similar to 70%) poling-induced EO coefficient (r(33)) values, as measured by simple reflection ellipsometry at 1310nm. This can be attributed to a roughly 2-fold enhancement in poling efficiency due to reduced intermolecular dipole-dipole interactions. This chromophore architecture also exhibits excellent temporal alignment stability and photochemical stability as compared to benchmark AJL8, FTC, and CLD chromophore systems. Incorporation of the strong CF3-phenyl-substituted tricyano-furan (TCF) acceptor into a bis(ProDOT)based chromophore resulted in a beta(zzz)( - 2 omega;omega,omega) value at 1907 nm of 5700 +/- 400 x 10(-30) esu and an r(33) value of 69 +/- 14 pm/V at 32.8 total chromophore weight %.