Polyacetylene Liquid Crystals: New Mesomorphic Materials with High Thermal Stability and Novel Light-Emitting Properties

摘要

A series of new disubstituted liquid crystalline polyacetylenes (LCPAs) with general molecular structures of -{(R)C=C[(CH_2)_m-Mes]}_n- and -[(C_6H_(13))C=C(C_6H_4-Mes)}]_n- (R = CH_3, C_6H_5, m = 3, 4, 9, Mes = mesogen) have been designed and synthesized. All the LCPAs are thermally stable and do not loss their weights when heated to a temperature as high as -400℃. While a few polymers exhibit nematicity, most of them form enantiotropic SA phase of monolayer structure. Upon photoexcitation, the polymers emit intense UV and blue lights with quantum yield up to 81%. Multilayer light-emitting diodes with a device configuration of ITO/PVK/PA/LiF/Al are constructed, which emits blue light with maximum luminance and external quantum efficiency of 119 cd/m~2 and 0.12%, respectively.