We study photoluminescence and triplet-triplet exciton annihilation in a neat film of a fac-tris(2-phenylpyridyl)iridium(III) [Ir (ppy)3] -cored dendrimer and in its blend with a 4, 4′ -bis (N -carbazolyl)biphenyl host for the temperature range of 77-300 K. The nearest neighbor hopping rate of triplet excitons is found to increase by a factor of 2 with temperature between 150 and 300 K and is temperature independent at lower temperature. The intermolecular quenching rate follows the Arrhenius law with an activation energy of 7 meV, which can be explained by stronger dipole-dipole interactions with the donor molecule in the higher triplet substate. The results indicate that energy disorder has no significant effect on triplet transport and quenching in these materials.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Feb 27 2008|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics