Highly stable binary cross-linkable organic nonlinear optical materials
using different acceptors based on Huisgen cycloaddition reaction
Abstract
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 Tg 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 hours, 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 (~40nm) 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.