Synthesis and characterization of Y-shaped optical nonlinear chromophores with strong acceptors

A series of Y-type chromophores L1-L3 containing bis( N , N -diethyl)aniline, bis( N -ethyl- N -phenylsilylethyl)aniline, and bis(3-phenylsilylpiperidin)aniline as electron donors, isophorone derivatives as a p-conjugated bridge, and phenyl-trifluoromethyl-tricyanofuran acceptors (CF 3 -TCF) as an acceptor were synthesized and investigated. However, the introduction of stronger acceptors does not guarantee the increase of electro-optical coefficients for all the chromophores. Chromophore L1 only achieved an r 33 value of 110 pm V −1 due to its large absorption at 1310 nm. Poled films of 100 wt% chromophores L2-L3 showed high poling efficiencies and electro-optic coefficient due to large steric hindrance and hyperpolarizability of the chromophores. An ultrahigh r 33 (351 pm V −1 and 277 pm V −1 ) and poling efficiency (3.50 + 0.10 nm 2 V −2 and 2.63 ± 0.08 nm 2 V −2 ) at 1310 nm were achieved for the film containing 100 wt% chromophores L2-L3 . These results indicate that the rational match between the strength of the donor, acceptor, and p-conjugated bridge plays an important role in achieving a large electro-optic coefficient. High r 33 and poling efficiency at 1310 nm were achieved for the film containing 100 wt% Y-type chromophores L2-L3 with double donors.