Theoretical study of asymmetric triazine host materials with diphenylphosphine oxide substituents

Recently, phosphorescent organic light-emitting diodes (PhOLEDs) have recieved considerable attention for their potential applications in full-color displays and large-area solid-state lighting. In this contribution, a series of triazine host materials with diphenylphosphine oxide substituents for PhOLEDs are designed and investigated by density functional theory (DFT). The triplet energy levels determined by the triazine core remain high (2.84~3.02 eV) at various substitution patterns of diphenylphosphine oxide and carbazole. Interestingly, the highest occupied molecular orbital (HOMO) dominated by the carbazole maintains around -5.85 eV, while the lowest unoccupied molecular orbital (LUMO) is independently tuned from -1.42eV to -2.33 eV according to the number of diphenylphosphine oxide substituent. For the high triplet energy level (3.02 eV), lower LUMO (-1.74 eV) and higher charge transfer, the two carbazole and one diphenylphosphine oxide substituted asymmetric triazine of DCzPT is suggested to be the best host materials for blue PhOLEDs.