Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells
Merve Karaman, Abhishek Kumar Gupta, Subeesh Madayanad Suresh, Tomas Matulaitis, Lorenzo Mardegan, Daniel Tordera, Henk J. Bolink, Sen Wu, Stuart L. Warriner, Ifor D. W. Samuel, Eli Zysman‐Colman
Abstract
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 (λ PL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λ PL = 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 × 10 3 s −1 and 3.04 × 10 3 s −1 . Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λ max = 534 nm) and red (λ max = 656 nm) emission, respectively.