Raghu Nath Bera

Time-Resolved Photoluminescence Study on Energy Transfer from Alq3 (tris(8-hydroxyquinoline)aluminum) to Red-Emissive Tetraphenylchlorin

Energy transfer and concentration quenching for a red-emitting electroluminescence system, tetraphenylchlorin (TPC)-doped tris(8-hydroxyquinoline)aluminum (Alq3) at various concentrations, were studied using a time-resolved photoluminescence (PL) technique. The PL decay of Alq3 in the presence of TPC was observed to be non-exponential in nature due to the Forster-type energy transfer from Alq3 to TPC. The PL decay of TPC became faster with the increase in TPC concentration due to the concentration quenching of TPC emission.

Highly branched phosphorescent dendrimers

A simple convergent procedure, involving the Diels-Alder reaction between 2,3,4,5-tetraphenylcyclopentadienone with an acetylene-substituted 2-phenylpyridine and subsequent complexation with iridium(III), has been developed for the formation of highly branched phosphorescent dendrimers. The procedure is demonstrated with the preparation of a first generation dendrimer composed of a fac-tris(2-phenylpyridyl)iridium(III) core with a single dendron attached to phenyl ring of each of the ligands. Each dendron is comprised of a branching phenyl unit with a further four phenyl groups attached. The lack of surface groups on the dendrons was found to reduce solubility of the dendrimers and allow strong intermolecular interactions of the emissive and electroactive cores in neat films. This was evidenced by a decrease in the photoluminescence quantum yield in going from solution to the solid state.