Quantum mechanics

Common emitter

Photochemistry

Materials science

Phosphorescence

Layer (electronics)

Atomic physics

Alkyl

Quantum yield

Electroluminescence

Diode

Physics

Quantum efficiency

Borylation

Organic chemistry

Exciton

Optics

Singlet state

Fluorescence

Excited state

OLED

Chemistry

Aryl

Optoelectronics

Journal of the American Chemical Society

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters have emerged as an important component of organic light-emitting diodes (OLEDs) because of their narrowband emission and high exciton utilization efficiency. However, the chemical space of MR-TADF emitters remains mostly unexplored because of the lack of suitable synthetic protocols. Herein, we demonstrate a sequential multiple borylation reaction that provides new synthetically accessible chemical space. ω-DABNA, the proof-of-concept material, exhibited narrowband green TADF with a full width at half-maximum of 22 nm and a small singlet-triplet energy gap of 13 meV. The OLED employing it as an emitter exhibited electroluminescence at 512 nm, with Commission International de l'Éclairage coordinates of (0.13, 0.73) and a high external quantum efficiency (EQE) of 31.1%. Moreover, the device showed minimum efficiency roll-off, with an EQE of 29.4% at 1000 cd m-2.

Sequential Multiple Borylation Toward an Ultrapure Green Thermally Activated Delayed Fluorescence Material