Tetracoordinate Boron‐Based Multifunctional Chiral Thermally Activated Delayed Fluorescence Emitters.

Purely organic emitters have shown great potential but still suffer from low efficiency in near‐infrared organic light‐emitting diodes (NIR‐OLEDs) due to the intensive non‐radiative recombination. In this contribution, two pairs of thermally activated delayed fluorescence (TADF) enantiomers (<italic>R</italic>/<italic>S‐</italic>DOBP and <italic>R</italic>/<italic>S‐</italic>HDOBP) with tetracoordinate boron geometries were designed and synthesized. The TADF emitters simultaneously showed aggregation‐induced emission, circularly polarized luminescence, high‐contrast mechanochromism, and piezochromism behaviors. More importantly, <italic>R</italic>/<italic>S‐</italic>DOBP and <italic>R</italic>/<italic>S‐</italic>HDOBP revealed high photoluminescence quantum yields and efficient reverse intersystem crossing in neat films. The nondoped solution‐processed OLEDs based on these unique emitters revealed the NIR emission (peaking at 716 nm) with a maximum external quantum efficiency of 1.9 % and high exciton utilization efficiency of 86 %, which represent one of the best solution‐processed nondoped NIR‐OLEDs. [ABSTRACT FROM AUTHOR]