Boosting the Efficiency and Stability of Blue TADF Emitters by Perdeuteration

Abstract

Abstract Highly efficient and stable blue organic light-emitting diodes (OLEDs), though desired for displays and lightings, remain rare after decades of research. Here we report a perdeuteration strategy to stabilize blue thermally activated delayed fluorescence (TADF) emitters. It is unveiled that deuteration would reduce the population at high vibrational energy levels by suppressing high-frequency vibrations, thus reducing the possibility of bond dissociation. Deuteration also leads to a denser packing of vibrational energy states, thus slowing down the internal conversion of the excited states to the ground and impeding non-radiative decay. The proof-of-concept perdeuterated blue TADF emitters concurrently exhibit not only higher efficiencies but also more than doubled lifetimes in OLEDs compared to protonated ones. By using them as sensitizers in TADF-sensitized fluorescent devices, a maximum external quantum efficiency of 33.1% and a superbly long LT80 (time to 80% of initial luminance) of 1,365 h with a Commission Internationale de l'Eclairage y-coordinate of 0.20 under 1,000 cd m− 2 are obtained simultaneously, even outperforming the best blue phosphorescent OLEDs.