An Exciplex-Based Light-Emission Pathway for Solution-State Electrochemiluminescent Devices (dataset)

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, we mitigate the effects of radical ions by using an exciplex formation pathway and demonstrate a remarkable improvement in luminance, luminous efficacy, and operational lifetime. Electron donor and acceptor molecules are dissolved at high concentrations and recombine 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, by applying a mesoporous TiO2 electrode, we increase the contact area and hence the number of molecules participating in ECL, thereby obtaining devices with a very high luminance of 3,790 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.