title: Aggregation-induced emission on benzothiadiazole dyads with large third-order optical nonlinearity.
abstract: 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 α2 fitting the experimental data are 6.3 × 10(-12) m W(-1) for BSC and 3.6 × 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.
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
authors.forename: Songhua
authors.initials: S
authors.lastname: Chen
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Qin
authors.forename: Taifeng
authors.initials: T
authors.lastname: Liu
authors.forename: Xingzhi
authors.initials: X
authors.lastname: Wu
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Li
authors.forename: Huibiao
authors.initials: H
authors.lastname: Liu
authors.forename: Yinglin
authors.initials: Y
authors.lastname: Song
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Li