Insights into enhanced electrochemiluminescence of a multiresonance thermally activated delayed fluorescence molecule

Funding: Walloon Region, Grant/Award Number:n1117545; Leverhulme Trust, Grant/Award Numbers: RPG‐2016047,SRF\R1\201089; Natural Sciences and Engineering Research Council Canada, Grant/Award Numbers: DG RGPIN‐2018‐06556, SPG STPGP‐2016‐493924; Fonds dela Recherche Scientifiques de Belgique, Grant/Award Numbers: 2.5020.11,F.4534.21; Engineering and Physical Sciences Research Council, Grant/Award Number: EP/P010482/1. The electrochemiluminescence (ECL) behavior of a multiresonance thermally activated delayed fluorescence molecule has been investigated for the first time by means of ECL-voltage curves, newly designed ECL-time observatory, and ECL spectroscopy. The compound, Mes3DiKTa, shows complex ECL behavior, including a delayed onset time of 5 ms for ECL generation in both the annihilation pathway and the coreactant route, which we attribute to organic long-persistent ECL (OLECL). Triplet-triplet annihilation, thermally activated delayed fluorescence and uncompensated solution resistance cannot be ruled out as contributing mechanisms to the ECL. A very long ECL emission decay was attributed to OLECL as well. The absolute ECL efficiencies of Mes3DiKTa were enhanced and reached 0.0013% in annihilation route and 1.1% for the coreactant system, which are superior to those of most other organic ECL materials. It is plausible that ECL materials with comparable behavior as Mes3DiKTa are desirable in applications such as ECL sensing, imaging, and light-emitting devices. Publisher PDF