Engineering the sign of circularly polarized emission in achiral polymer – chiral small molecule blends as a function of blend ratio

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Title: Engineering the sign of circularly polarized emission in achiral polymer – chiral small molecule blends as a function of blend ratio
Authors: Wan, L
Wade, J
Wang, X
Campbell, A
Fuchter, M
Item Type: Journal Article
Abstract: Circularly polarized organic light-emitting diodes (CP-OLEDs) that demonstrate both state-of-the-art efficiency and strongly circularly polarized (CP) electroluminescence have proved a considerable technical challenge. Furthermore, multiple factors – from film thickness to device structure – have been shown to influence the sign of the emitted CP light, independent of the handedness (absolute stereochemistry) of the chiral emitter. Here we report CP-OLEDs using a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and a chiral small molecule additive (1-aza[6]helicene, aza[6]H). We demonstrate CP-OLEDs with an impressive electroluminescence dissymmetry (gEL) > 0.3 and a current efficiency of 0.53 cd A−1 and brightness of 3023 cd m−2. While at low aza[6]H loadings, F8T2 blends are consistent with previous observations of CP dissymetric inversion as a function of film thickness/excitation mode, a higher loading of aza[6]H (∼40 wt%) removes such dependencies while retaining excellent g-factors. The materials disclosed will allow for further mechanistic studies of chiral polymeric materials and provide new opportunities for chiroptical optimisation in films and devices.
Issue Date: 25-Feb-2022
Date of Acceptance: 25-Feb-2022
DOI: 10.1039/d1tc05403a
ISSN: 2050-7526
Publisher: Royal Society of Chemistry (RSC)
Start Page: 5168
End Page: 5172
Journal / Book Title: Journal of Materials Chemistry C
Volume: 10
Issue: 13
Copyright Statement: This journal is © The Royal Society of Chemistry 2022 J. Mater. Chem. C
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/P000525/1
Keywords: Science & Technology
Physical Sciences
Materials Science, Multidisciplinary
Physics, Applied
Materials Science
0303 Macromolecular and Materials Chemistry
0306 Physical Chemistry (incl. Structural)
0912 Materials Engineering
Publication Status: Published
Embargo Date: 2023-02-24
Online Publication Date: 2022-02-25
Appears in Collections:Materials
Faculty of Natural Sciences
Faculty of Engineering