Acceptor

Common emitter

Photochemistry

Materials science

Layer (electronics)

Dopant

Molecule

Photoluminescence

Electroluminescence

Diode

Heteroatom

Physics

Quantum efficiency

Nanotechnology

Organic chemistry

Optics

HOMO/LUMO

Doping

Deep blue

Fluorescence

Condensed matter physics

OLED

Chemistry

Optoelectronics

Ring (chemistry)

Advanced Functional Materials

Simultaneously obtaining high efficiency and deep blue emission in organic light emitting diodes (OLEDs) remains a challenge. To overcome the demands associated with deep blue thermally activated delayed fluorescence (TADF) emitters, two deep blue TADF materials namely, DBA–BFICz and DBA–BTICz, are designed and synthesized by incorporating oxygen‐bridged boron (DBA) acceptor with heteroatoms, oxygen and sulphur‐based donors, BFICz and BTICz, respectively. Both TADF materials show deep blue photoluminescence emissions below 450 nm by enhancing the optical band gap over 2.8 eV through deeper highest occupied molecular orbital (HOMO) level of heteroatom based donor moieties. At the same time, the photoluminescence quantum yields (PLQYs) of both TADF materials remain over 94%. The TADF device with DBA–BFICz as an emitter exhibits a good external quantum efficiency (EQE) of 33.2%. Since both new TADF materials show deep blue emissions and high efficiencies, hyperfluorescence (HF) OLED devices are fabricated using ν‐DABNA as a fluorescence dopant. DBA–BFICz as a TADF sensitized host in HF–OLED reveals an outstanding EQE of 38.8% along with narrow full width at half maximum of 19 nm in the bottom emission pure blue OLEDs. This study provides an approach to develop deep blue TADF emitters for highly efficient OLEDs.

Achieving Narrow FWHM and High EQE Over 38% in Blue OLEDs Using Rigid Heteroatom‐Based Deep Blue TADF Sensitized Host