Two bipolar host materials H1 (N-linked carbazole) and H2 (C-3-linked carbazole) via changing the substitution position of triazine and carbazole moieties are reported. Their structural and physical properties were fully characterized. The thermal analysis demonstrated that both H1 and H2 are of high thermal stability. The triplet energy levels of H1 and H2 were determined to be 2.64 and 2.7 eV, respectively. Both green and blue OLEDs with H1 and H2 acting as host materials were fabricated to investigate their performances in PHOLED. The green PHOLED based on H1 exhibits the best performance with the maximum current efficiency, maximum power efficiency and maximum brightness of 51.7 cd/A, 37.8 lm/W and 132800 cd/m2, respectively, while the blue PHOLED based on H2 shows the best performance with the maximum current efficiency, maximum power efficiency and maximum brightness of 21.6 cd/A, 17.2 lm/W and 16640 cd/m2, respectively. The characteristic measurements of OLED devices reveal that both H1 and H2 are promising host materials for practical application. By comparing the commercial host materials of 4,4’-bis(carbazol-9-yl)biphenyl (CBP) and N,N-dicarbazoyl-3,5-benzene (mCP), the power efficiencies of green and blue PHOLED were boosted by 22.3% and 75.5%, respectively.
Scopus Subject Areas
- Chemical Engineering(all)
- Process Chemistry and Technology
- Bipolar host materials
- Carbazole derivatives
- Phosphorescent organic light-emitting diodes
- Triazine derivatives