Triplet state and phosphorescence of hole-transport layer and its triplet exciton confinement

The triplet state of 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA) and the dynamics of the singlet and the triplet states were examined to understand the confinement effect of m-MTDATA as host materials for phosphorescent organic light-emitting diodes. The time-resolved photoluminescence spectra revealed phosphorescence at approximately 480 nm (2.58 eV). The time constant of the T1 state was 1.2 μs. The dynamics of delayed fluorescence was closely related to that of phosphorescence. The triplet energy of a green phosphorescent sensitizer was well-confined in the m-MTDATA host, which suggests the application of m-MTDATA as possible host materials.