Dynamic bond interactions fine-tune the properties of multiple resonance emitters towards highly efficient narrowband green OLEDs

Abstract

Multiple resonance (MR) molecules based on a B/N polycyclic aromatic framework are the cutting-edge materials in the field of organic light-emitting diodes (OLEDs) owing to their superb photophysical properties. Tailoring the MR molecular framework with various functional groups toward ideal properties has become an emerging topic in the field of materials chemistry. Dynamic bond interactions are versatile and powerful tools in regulating the properties of materials. Herein, the pyridine moiety, which presents high affinity to form dynamic bond interactions such as hydrogen bonds and N→B dative bonds, was introduced into the MR framework for the first time, and the designed emitters are synthesized in a feasible way. The introduction of the pyridine moiety not only maintained the conventional MR properties of the emitters, but also endowed the emitters with tunable emission spectra, narrowed emission, enhanced photoluminescence quantum yield (PLQY), and intriguing supramolecular assembly in the solid state. Thanks to the overall superior properties brought by the hydrogen-bond promoted molecular rigidity, green OLEDs based on the emitter exhibit excellent device performance with external quantum efficiency (EQE) up to 38% and a small FWHM of 26 nm, together with good roll-off performance.