Issue 13, 2022

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

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.

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

Supplementary files

Article information

Article type
Paper
Submitted
09 nov 2021
Accepted
25 feb 2022
First published
25 feb 2022
This article is Open Access
Creative Commons BY-NC license

J. Mater. Chem. C, 2022,10, 5168-5172

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

L. Wan, J. Wade, X. Wang, A. J. Campbell and M. J. Fuchter, J. Mater. Chem. C, 2022, 10, 5168 DOI: 10.1039/D1TC05403A

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