Introducing MR‐TADF emitters into Light‐Emitting Electrochemical Cells for narrowband and efficient emission
Abstract
Organic semiconductors that emit by the process of multi‐resonance thermally activated delayed fluorescence (MR‐TADF) can deliver narrowband and efficient electroluminescence while being processable from solvents and metal‐free. This renders them attractive for use as the emitter in sustainable light‐emitting electrochemical cells (LECs), but so far reports of narrowband and efficient MR‐TADF emission from LEC devices are absent. Here, this issue is addressed through careful and systematic material selection and device development. Specifically, the authors show that the detrimental aggregation tendency of an archetypal rigid and planar carbazole‐based MR‐TADF emitter can be inhibited by its dispersion into a compatible carbazole‐based blend host and an ionic‐liquid electrolyte, and it is further demonstrated that the tuning of this active material results in a desired balanced p‐ and n‐type electrochemical doping, a high solid‐state photoluminescence quantum yield of 91%, and singlet and triplet trapping on the MR‐TADF guest emitter. The introduction of this designed metal‐free active MR‐TADF material into a LEC, employing air‐stabile electrodes, results in bright blue electroluminescence of 500 cd m−2, which is delivered at a high external quantum efficiency of 3.8% and shows a narrow emission profile with a full‐width‐at‐half‐maximum of 31 nm.
Citation
Tang , S , dos Santos , J M , Ràfols‐Ribé , J , Wang , J , Zysman‐Colman , E & Edman , L 2023 , ' Introducing MR‐TADF emitters into Light‐Emitting Electrochemical Cells for narrowband and efficient emission ' , Advanced Functional Materials . https://doi.org/10.1002/adfm.202306170
Publication
Advanced Functional Materials
Status
Peer reviewed
ISSN
1616-301XType
Journal article
Description
The Umeå University authors wish to acknowledge generous financial support from the Swedish Research Council, the Swedish Energy Agency, Bertil och Britt Svenssons stiftelse för belysningsteknik, Länsstyrelsen Västerbotten, Kempestiftelserna, Olle Engkvists Stiftelse, Wenner-Gren Foundations, and the Wallenberg Initiative Materials Science for Sustainability, WISE. The St Andrews authors thank the Engineering and Physical Sciences Research Council (EP/R035164/1).Collections
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