Highly Stable Binary Cross-Linkable Organic Nonlinear Optical Materials Using Different Acceptors Based on Huisgen Cycloaddition Reaction

How to obtain organic electro-optic materials with large electro-optic coefficients, high glass transition temperature, and good optical transparency remains a challenge in this field. To solve this problem, we introduce groups that can undergo Huisgen cycloaddition reactions into the donor and electron bridge of chromophores with large hyperpolarizability using tetrahydroquinoline as the donor. Binary cross-linkable chromophores TLD1-2 with CF₃-TCF as the acceptor and chromophores TLD3-4 with 5Fph-TCF as the acceptor were synthesized. After poling and crosslinking, the T_g of TLD1/TLD2 and TLD3/TLD4 were raised to 152 and 174 °C, respectively. The electro-optical coefficients of chromophores TLD1/TLD2 and TLD3/TLD4 were as high as 312 pm/V and 287 pm/V, respectively. The long-term alignment stability test showed that after being left at 85 °C for 500 h, the cross-linked film TLD3/TLD4 can still maintain more than 98% of the original electro-optical coefficient value, which is higher than that of TLD1/TLD2 (93%). The chromophore TLD3-4 exhibited much blue-shifted maximum absorption wavelengths (~40 nm) compared to TLD1-2 which was beneficial for reducing optical loss in the device. The combination of high electro-optic coefficient, strong stability, and excellent optical transparency makes the TLD series of binary cross-linked materials very promising for practical high-performance electro-optic devices.