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We designed and synthesized two new ionic thermally activated delayed fluorescent (TADF) emitters that are charged analogues of a known multiresonant TADF (MR-TADF) compound, DiKTa. The emission of the charged derivatives is red-shifted compared to the parent compound. For instance, DiKTa-OBuIm emits in the green (λPL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λPL = 577 nm, 1 wt % in mCP). In 1 wt % mCP films, both emitters showed good photoluminescence quantum yields of 71% and 61%, and delayed lifetimes of 316.6 μs and 241.7 μs, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm, leading to reverse intersystem crossing rates of 2.85 × 103 s−1 and 3.04 × 103 s−1. Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λmax = 534 nm) and red (λmax = 656 nm) emission, respectively.

In this work we showcase the emitter DICzTRZ in which we employed a twin-emitter design of our previously reported material, ICzTRZ. This new system presented a red-shifted emission at 488 nm compared to that of ICzTRZ at 475 nm and showed a comparable photoluminescence quantum yield of 57.1% in a 20 wt % CzSi film versus 63.3% for ICzTRZ. The emitter was then incorporated within a solution-processed organic light-emitting diode that showed a maximum external quantum efficiency of 8.4%, with Commission Internationale de l’Éclairage coordinate of (0.22, 0.47), at 1 mA cm−2.