A Theoretical Guideline for Designing Effective Host Materials Based on 4,4′-Bis(9-carbazolyl)-1,1′-biphenyl Derivatives for Blue Phosphorescent Devices

Development of host materials is crucial for organic electroluminescent devices. In order to generalize the way to molecular design the host materials, we here present a guideline to design effective host materials for blue phosphorescent devices based on 4,4′-bis(9-carbazolyl)-1,1′-biphenyl (CBP) derivatives, comparing some theoretical parameters of seven CBP derivatives with experimental ones in terms of thermal stability, T1 energy level, and band gap. Although our computation at the density functional theory level could not reproduce the absolute values and phenomena that were experimentally obtained, theoretical relative correlations between different molecules agreed with experimental ones. Indeed, both experimental and theoretical approaches predicted that the same molecule (1,1-bis(4-(9-carbazolyl)-phenyl)cyclohexane) was viable as blue host material among the target molecules in terms of thermal stability, the T1 state with the LE character within carbazole moieties and T1 energy 3.00 eV higher t...