Robust Angular Anisotropy of Circularly Polarized Luminescence from a Single Twisted-Bipolar Polymeric Microsphere

Osamu Oki, Chidambar Kulkarni, Hiroshi Yamagishi, Stefan C.J. Meskers, Zhan Hong Lin, Jer Shing Huang, E.W. Meijer, Yohei Yamamoto (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

51 Citations (Scopus)
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Abstract

It has long been surmised that the circular polarization of luminescence (CPL) emitted by a chiral molecule or a molecular assembly should vary with the direction in which the photon is emitted. Despite its potential utility, this anisotropic CPL has not yet been demonstrated at the level of single molecules or supramolecular assemblies. Here we show that conjugated polymers bearing chiral side chains self-assemble into solid microspheres with a twisted bipolar interior, which are formed via liquid-liquid phase separation and subsequent condensation into a cholesteric lyotropic liquid crystalline mesophase. The resultant microspheres, when dispersed in methanol, exhibit CPL with a glum value as high as 0.23. The microspheres are mechanically robust enough to be handled with a microneedle under ambient conditions, allowing comprehensive examination of the angular anisotropy of CPL. The single microsphere is found to exhibit distinct angularly anisotropic birefringence and CPL with glum up to ∼0.5 in the equatorial plane, which is 2.5-fold greater than that along the polar axis. Such optically anisotropic solid materials are important for the application to next-generation microlight-emitting and visualizing devices as well as for fundamental optics studies of chiral light-matter interaction.

Original languageEnglish
Pages (from-to)8772-8779
Number of pages8
JournalJournal of the American Chemical Society
Volume143
Issue number23
DOIs
Publication statusPublished - 16 Jun 2021

Bibliographical note

Funding Information:
The authors acknowledge Ms. Yuko Jinzenji for TEM observation of the slices of the microspheres. This work was supported by CREST (JPMJCR20T4) and ACT-X (JPMJAX201J) from Japan Science and Technology Agency (JST), Grant-in-Aid for Scientific Research on Innovative Areas “π-System Figuration” (JP17H05142), Scientific Research (A) (JP16H02081), and Young Scientist (JP19J20398) from Japan Society for the Promotion of Science (JSPS), a bilateral joint research program between JSPS and DAAD (BBD30033 and 57402047), Ogasawara Foundation, Kato Foundation for the Promotion of Science (KS-3223), and DFG (HU2626/3-1, HU2626/5-1, SFB 1375-C1). The work in Eindhoven was funded by NWO (TOP-PUNT Grant 10018944) and the Dutch Ministry of Education, Culture and Science (Gravity Program 024.001.035).

Publisher Copyright:
© 2021 American Chemical Society.

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