Synthesis and Characterization of Boron Based Efficient and Pure Blue TADF Materials for Organic Light Emitting Diodes

The development of thermally activated delayed fluorescent (TADF) emitters has greatly improved the efficiency of the fluorescent organic light emitting diodes (OLEDs). We report two highly efficient deep blue thermally activated delayed fluorescence emitters, TDBA–SAF and DBA–SAB, containing spiro acridine fluorene and spiro biacridine donor units with an oxygen bridged boron acceptor unit, respectively. The OLEDs emit deep blue color and blue color with the peak wavelength of 456 nm for TDBA–SAF and 472 nm for DBA–SAB, respectively. Both devices exhibited a narrow emission spectrum with FWHM of 55 and 62 nm due to the rigidity of the boron acceptor unit. The blue TADF device with TDBA–SAF and DBA–SAB in the DPEPO host exhibited a maximum EQE of 28.2% and 25.7% with CIE coordinates of (0.142, 0.090) and (0.144, 0.212), respectively.