Multiresonant Thermally Activated Delayed Fluorescence Emitters Based on Heteroatom-Doped Nanographenes: Recent Advances and Prospects for Organic Light-Emitting Diodes

Since the first report in 2015, multiresonant thermally activated delayed fluorescent (MR-TADF) compounds, a subclass of TADF emitters based on a heteroatom-doped nanographene material, have come to the fore as attractive hosts as well as emitters for organic light-emitting diodes (OLEDs). MR-TADF compounds typically show very narrow-band emission, high photoluminescence quantum yields, and small ΔE_ST values, typically around 200 meV, coupled with high chemical and thermal stabilities. These materials properties have translated into some of the best reported deep-blue TADF OLEDs. Here, a detailed review of MR-TADF compounds and their derivatives reported so far is presented. This review comprehensively documents all MR-TADF compounds, with a focus on the synthesis, optoelectronic behavior, and OLED performance. In addition, computational approaches are surveyed to accurately model the excited state properties of these compounds.