Aggregation-induced emission on benzothiadiazole dyads with large third-order optical nonlinearity

作者:Chen, Songhua; Qin, Zhihong; Liu, Taifeng; Wu, Xingzhi; Li, Yongjun; Liu, Huibiao; Song, Yinglin; Li, Yuliang
来源:Physical Chemistry Chemical Physics, 2013, 15(30): 12660-12666.
DOI:10.1039/c3cp51273h

摘要

Two kinds of D-A molecular of (4-(4-(9H-carbazol-9-yl)phenyl))-7-nitrobenzothiadiazole (BSC) and 4-((4-(9H-carbazol-9-yl) phenyl) ethynyl)-7-nitrobenzothiadiazole (BEC) containing carbazole moieties as the donor were synthesized. X-ray crystal data elucidated the multiple intermolecular interactions. They exhibit distinctly different self-assembly behaviours. The nonlinear optical properties were studied using the top-hat Z-scan technique at 532 nm with a 21 ps pulse. The results indicate that they exhibit large third-order nonlinear absorption effects. The nonlinear absorption coefficients alpha(2) fitting the experimental data are 6.3 x 10(-12) m W-1 for BSC and 3.6 x 10(-11) m W-1 for BEC. The time-resolved pump-probe results show that both nonlinear absorption and nonlinear refraction of BEC in CH2Cl2 solution have rapid optical responses, which indicate the nonlinear absorption and nonlinear refraction mechanism are excited-state nonlinear. Moreover, both of these two compounds are observed to be aggregation-induced emission (AIE) active. The aggregates of the well-formed one-dimensional microrods of BEC and BSC endow the material with potential applications in the field of optical devices.