Iwai Kohei, Yamagishi Hiroshi, Herzberger Colin, Sato Yuji, Tsuji Hayato, Albrecht Ken, Yamamoto Kimihisa, Sasaki Fumio, Sato Hiroyasu, Asaithambi Aswin, Lorke Axel, Yamamoto Yohei
Department of Materials Science, Faculty of Pure and Applied Sciences, and, Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan.
Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, 259-1293, Japan.
Angew Chem Int Ed Engl. 2020 Jul 27;59(31):12674-12679. doi: 10.1002/anie.202000712. Epub 2020 May 20.
Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First-, second-, and third-generation carbazole (Cz) dendrimers with a carbon-bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1-3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2- and G3COPV2 align omnidirectionally. The dendrons work as light-harvesting antennas that absorb non-polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers.
微晶是很有前景的微型无镜激光源。沿着这条路线已经开发了多种发光有机化合物，但树枝状聚合物由于其易碎性和极差的结晶度而无法适用。现在，提出了一个克服这些困难的树枝状聚合物家族。具有碳桥联低聚（亚苯基乙烯基）（COPV2）核（GnCOPV2，n = 1 - 3）的第一代、第二代和第三代咔唑（Cz）树枝状聚合物组装形成微晶。COPV2核在晶体中单向/双向排列，而G2 - 和G3COPV2中的Cz单元则全方位排列。树枝状支链充当光捕获天线，吸收非偏振光并将其转移到COPV2核，从该核发出偏振发光。此外，这些晶体充当激光谐振器，其中激光阈值与晶体形态和COPV2的取向强烈耦合，这与传统的无定形树枝状聚合物形成对比。
