Effect of the environment on tris(2-phenylpyridine) iridium molecules embedded in a polyvinyl carbazole matrix

The luminescence of tris(2-phenylpyridine) iridium (Ir(ppy)3) in poly (N-vinylcarbazole) (PVK) is characterized at different temperatures ranging from 80 to 300 K and compared to the emission in other environments. The luminescence from Ir(ppy)3 is found to be dominated by the emission from different triplet substates, which is markedly affected by the environment of this molecule. Resonant energy transfer appears to enhance the harvest of triplet excitons from PVK to Ir(ppy)3. The alteration of the zero-field splitting values upon modifying the molecular environment and the thermal stability of the emission are also unveiled.