文献类型：期刊文献

英文题名：The influence of aggregation on the third-order nonlinear optical property of π-conjugated chromophores: the case of cyanine dyes

作者：Wang, Chao[1];Yuan, Yizhong[2,3]

机构：[1]Zhejiang Univ, Dept Polymer Sci & Engn, MOE Key Lab Macromol Synth & Functionalizat, Hangzhou 310027, Zhejiang, Peoples R China;[2]East China Univ Sci & Technol, Key Lab Ultrafine Mat, Minist Educ, Shanghai 200237, Peoples R China;[3]East China Univ Sci & Technol, Shanghai Key Lab Adv Polymer Mat, Sch Mat Sci & Engn, Dept Mat Sci & Engn, Shanghai 200237, Peoples R China

年份：2018

卷号：20

期号：24

起止页码：16777

外文期刊名：PHYSICAL CHEMISTRY CHEMICAL PHYSICS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000436032900050)】；

语种：英文

摘要：The external molecular environment like the aggregation of molecules can significantly change the intrinsic third-order nonlinear optical (NLO) property of -conjugated chromophores. A combined experimental and theoretical study was performed to understand the influence of the aggregation of cyanines on the third-order NLO property in spin-coated thin films. Our result indicates that the H and J type cyanine dimers prefer the polyene-like structures and the P type dimer displays a comparatively smaller bond length alternation (BLA). The polarizable continuum model (PCM)-tuned, range-separated (RSE) density functional approach was used to describe the screening effect of the cyanine aggregation. In the thin film, the P aggregate has very small positive isotropic averaged second hyperpolarizability , while the J aggregate has the largest positive due to the most polarized face-to-tail cyanine-cyanine interaction. Hence, the of the isolated cyanines (negative ) may get cancelled against that of the cyanine aggregates (positive ) in the thin film. The forward degenerate four-wave mixing technique also confirms a decrease in the magnitude of with an increase in the aggregation degree of cyanines. Since the large positive of the cyanine also implies strong two-photon absorption (TPA), the J aggregation of cyanines can be used as a potential fabrication method for applications involving TPA.