Boron

Photochemistry

Materials science

Embedded system

Layer (electronics)

Atomic physics

Alkyl

Molecule

Computer science

Photoluminescence

Quantum yield

Electroluminescence

Physics

Quantum efficiency

Borylation

Nanotechnology

Organic chemistry

Oxygen

Optics

Hypsochromic shift

HOMO/LUMO

Singlet state

Resonance (particle physics)

Fluorescence

Atom (system on chip)

Excited state

OLED

Chemistry

Aryl

Intersystem crossing

Resonance fluorescence

Optoelectronics

Angewandte Chemie International Edition

Herein, we reported an ultrapure blue multiple‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) material ( ν‐DABNA‐O‐Me ) with a high photoluminescence quantum yield and a large rate constant for reverse intersystem crossing. Because of restricted π‐conjugation of the HOMO rather than the LUMO induced by oxygen atom incorporation, ν‐DABNA‐O‐Me shows a hypsochromic shift compared to the parent MR‐TADF material ( ν‐DABNA ). An organic light‐emitting diode based on this material exhibits an emission at 465 nm, with a small full‐width at half‐maximum of 23 nm and Commission Internationale de l'Eclairage coordinates of (0.13, 0.10), and a high maximum external quantum efficiency of 29.5 %. Moreover, ν‐DABNA‐O‐Me facilitates a drastically improved efficiency roll‐off and a device lifetime compared to ν‐DABNA , which demonstrates significant potential of the oxygen atom incorporation strategy.

Hypsochromic Shift of Multiple‐Resonance‐Induced Thermally Activated Delayed Fluorescence by Oxygen Atom Incorporation