Single‐Crystalline Optical Microcavities from Luminescent Dendrimers. (20th May 2020)

• Record Type: Journal Article
• Authors: Iwai, Kohei; Yamagishi, Hiroshi; Herzberger, Colin; Sato, Yuji; Tsuji, Hayato; Albrecht, Ken; Yamamoto, Kimihisa; Sasaki, Fumio; Sato, Hiroyasu; Asaithambi, Aswin; Lorke, Axel; Yamamoto, Yohei
• Is Part Of: Angewandte Chemie. Volume 132:Number 31(2020)
• Page Start: 12774
• Page End: 12779
• Publication Date: 2020-05-20
• Subjects: dendrimers -- laser chemistry -- light harvesting -- microcavities -- photochemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202000712
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: 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 (G n COPV2, 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. Abstract : Carbon‐bridged oligo(phenylenevinylene) (COPV2)–carbazole core–shell dendrimers with molecular weight as large as 4600 g mol −1 form microcrystals in which dendrons and COPV2 work as light‐harvesting antenna and fluorophore, respectively. The microcrystals function as a laser resonator, where the light confinement mode tightly couples with the alignment of the dendrimers and the morphology of the crystals.