Novel Space-Crowded Through-Space Charge Transfer Molecules for the Fabrication of Efficient Blue OLEDs

Currently, the advance of high-resolution display device puts a high requirement for the development of efficient luminescent materials emitting high-quality blue light. But stable blue luminescent materials with high electroluminescence (EL) efficiencies and narrow emission spectra are still rare. In this work, two efficient blue molecules (mCPTC and 2mCPTC) are developed by linking large-volume electron donors of 1,3-bis(N-carbazolyl)benzene (mCP) and electron acceptor of 2,4-diphenyl-1,3,5-triazine (DPTRZ) on the 3,6-di(tert-butyl)carbazole holder through benzene bridges. Their thermal stability, crystal and electronic structures, energy levels, photophysical property, charge transport ability and EL behaviors are thoroughly studied. They hold high structural rigidity and through-space charge transfer characteristics between donor and acceptor, and exhibit strong deep blue photoluminescence. They can not only function as emitters in OLEDs to radiate deep blue light, but also serve as efficient hosts for blue multi-resonance emitter v-DABNA, providing narrow EL spectra and excellent EL efficiencies of 24.21 %, much higher than those in common host without sensitizers. These results demonstrate the good potentials of these blue molecules in the fabrication of efficient narrow-spectrum blue OLEDs.