A simple molecular design strategy for delayed fluorescence towards 1000 nm

Harnessing the near-infrared (NIR) region of the electromagnet-ic spectrum is exceedingly important for photovoltaics, tele-communications and the biomedical sciences. While thermally activated delayed fluorescent (TADF) materials have attracted much interest due to their intense luminescence and narrow exchange energies (ΔEST), they are still greatly inferior to con-ventional fluorescent dyes in the NIR, which precludes their application. This is because securing a sufficiently strong do-nor–acceptor (D–A) interaction for NIR emission alongside the narrow ΔEST required for TADF is highly challenging. Here, we demonstrate that by abandoning the common polydonor model in favor of a D–A dyad structure, a sufficiently strong D–A inter-action can be obtained to realize a TADF emitter capable of pho-toluminescence (PL) close to 1000 nm. Electroluminescence (EL) at a peak wavelength of 904 nm is also reported. This strategy is both conceptually and synthetically simple and of-fers a new approach to the developm...