An exciplex-based light-emission pathway for solution-state electrochemiluminescent devices
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Electrochemiluminescence (ECL) allows the design of unique light-emitting devices that use organic semiconductors in a liquid or gel state, which allows for simpler and more sustainable device fabrication and facilitates unconventional device form-factors. Compared to solid-state organic LEDs, ECL devices (ECLDs) have attracted less attention due to their currently much lower performance. ECLD operation is typically based on an annihilation pathway that involves electron transfer between reduced and oxidized luminophore species; the intermediate radical ions produced during annihilation dramatically reduce device stability. Here, the effects of radical ions are mitigated by an exciplex formation pathway and a remarkable improvement in luminance, luminous efficacy, and operational lifetime is demonstrated. Electron donor and acceptor molecules are dissolved at high concentrations and recombined as an exciplex upon their oxidization/reduction. The exciplex then transfers its energy to a nearby dye, allowing the dye to emit light without undergoing oxidation/reduction. Furthermore, the application of a mesoporous TiO2 electrode increases the contact area and hence the number of molecules participating in ECL , thereby obtaining devices with a very high luminance of 3790 cd m−2 and a 30-fold improved operational lifetime. This study paves the way for the development of ECLDs into highly versatile light sources.
Moon , C-K , Butscher , J F & Gather , M C 2023 , ' An exciplex-based light-emission pathway for solution-state electrochemiluminescent devices ' , Advanced Materials , vol. 35 , no. 38 , 2302544 . https://doi.org/10.1002/adma.202302544
Copyright © 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
DescriptionThis work was financially supported by the Alexander von Humboldt Foundation (Humboldt-Professorship to M.C.G.). C.K.M. acknowledges funding from the European Commission through a Marie Skłodowska Curie individual fellowship (101029807). J.F.B. acknowledges funding from Beverly and Frank MacInnis via the University of St Andrews.
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