We synthesize four anthracene-based bipolar host materials. The external quantum efficiency and the max luminance of the deep blue OLEDs reaches 8.10% and 7973 cd m−2, and the CIE is (0.1298, 0.1712) with a low efficiency roll-off of only 2.9%.
Three new U-shaped host materials, namely, DPPI-DBF, Cz-PPI-DBF and TPA-PPI-DBF, were designed and synthesized by employing a dibenzofuran bridge linker combining one phenanthroimidazole (PPI) unit with PPI/carbazole (Cz)/triphenylamine (TPA) units.
Double boron-based multiresonance emitters DBF-DBN and DBT-DBN have been synthesized. The OLED device based on DBT-DBN shows an ultrapure green emission at 520 nm with EQEs up to 31.3% and a narrow FWHM of 24 nm.
Regioisomeric effects have a profound impact on the OLED efficiency. DABNA-3-DBF demonstrated enhanced PLQY and a EQEmax of 25.9%, showcasing optimized conjugation for greater performance.
Across a chemically robust DBF–biphenyl host series, trap-assisted charge accumulation, not just intrinsic bond stability and high T1, is critical for blue TADF-OLED lifetime. 4-Linked hosts deliver the best efficiency–stability balance.