Engineering the sign of circularly polarized emission in achiral polymer - chiral small molecule blends as a function of blend ratioShow others and affiliations
2022 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 10, no 13, p. 5168-5172Article in journal (Refereed) Published
Abstract [en]
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 (g(EL)) > 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 (similar to 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.
Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY , 2022. Vol. 10, no 13, p. 5168-5172
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:liu:diva-183575DOI: 10.1039/d1tc05403aISI: 000764248100001OAI: oai:DiVA.org:liu-183575DiVA, id: diva2:1645480
Note
Funding Agencies|EPSRCUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/P000525/1, EP/L016702/1, EP/R00188X/1]
2022-03-172022-03-172023-05-24Bibliographically approved