Enhancing performance for blue TADF emitters by introducing intramolecular CH⋯N hydrogen bonding between donor and acceptor

Abstract

Three novel thermally activated delayed fluorescence (TADF) emitters, named MCZ-B-DTM, MCZ-P2-DTM and MCZ-P3-DTM are designed and synthesized for fabricating blue emission devices. The position of nitrogen atom in pyridine ring is varied relative to the donor unit and the presence of CH⋯N hydrogen bonding in MCZ-P3-DTM is confirmed by theoretic simulation and 1H NMR analysis. Due to the introduction of CH⋯N hydrogen bonding between donor and acceptor, the dihedral angles, photophysical properties, together with thermal stabilities, of the targeted compounds are regulated ingeniously. As a consequence, MCZ-P3-DTM displays an increase of the molar extinction coefficient obviously and offers a higher PLQY of 60.1%. The TADF device adopting MCZ-P3-DTM as emitter shows a maximum external quantum efficiency (EQE) of 12.1%, which is superior to those of MCZ-B-DTM and MCZ-P2-DTM, demonstrating the introducing of intramolecular hydrogen bonding interactions between donor and acceptor is an efficient strategy for future structural design of TADF emitters.