Isomerization design for improving the efficiency of red thermally activated delayed fluorescence emitters based on pyridopyrazinophenanthroline acceptor

A novel rigid acceptor PPP was developed, and two red TADF isomers were designed and synthesized. The device based on otriTPA-PPP shows excellent performance with EQE max of 24.8% at 597 nm due to the introducing of intramolecular H-bonding.