Amplified circularly polarized phosphorescence from co-assemblies of platinum(ii) complexes

Gyurim Park, Hyungchae Kim, Hoichang Yang, Kyung Ryoul Park, Inho Song, Joon Hak Oh, Changsoon Kim, Youngmin You

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82 Scopus citations

Abstract

Molecules capable of producing zero-field circularly polarized phosphorescence (CPP) are highly valuable for chiroptoelectronic applications that rely on triplet exciton. However, the paucity of tractable molecular design rules for obtaining CPP emission has inhibited full utilization. We report amplification of CPP by the formation of helical co-assemblies consisting of achiral square planar cycloplatinated complexes and small fractions of homochiral cycloplatinated complexes. The latter has a unique Pfeiffer effect during the formation of superhelical co-assemblies, enabling versatile chiroptical control. Large dissymmetry factors in electronic absorption (gabs, 0.020) and phosphorescence emission (glum, 0.064) are observed from the co-assemblies. These values are two orders of magnitude improved relative to those of individual molecules. In addition, photoluminescence quantum yields (PLQY) also increase by a factor of ten. Our structural, photophysical, and quantum chemical investigations reveal that the chiroptical amplification is attributable to utilization of both the magnetically allowed electronic transition and asymmetric coupling of excitons. The strategy overcomes the trade-off between glum and PLQY which has frequently been found for previous molecular emitters of circularly polarized luminescence. It is anticipated that our study will provide new insight into the future research for the exploitation of the full potential of CPP.

Original languageEnglish
Pages (from-to)1294-1301
Number of pages8
JournalChemical Science
Volume10
Issue number5
DOIs
StatePublished - 2019

Bibliographical note

Funding Information:
This work was supported by a grant from the Samsung Research Funding Center for Future Technology (SRFC-MA1602-03). H. Y. acknowledges the grant provided by the National Research Foundation of Korea (NRF2017R1A2B4009313).

Publisher Copyright:
© 2019 The Royal Society of Chemistry.

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