Concentration quenching of a red emitting electroluminescent dye tetraphenylporphyrin: A time-resolved photoluminescence study

This work deals with the steady-state and time-resolved photoluminescence study of a well-known red emitting electroluminescent dye, tetraphenylporphyrin (TPP), doped in poly(methylmethacrylate). From the time-resolved photoluminescence (PL) study, exponential decay of TPP emission was observed for these doped films in the studied concentrations region (10(-4)-10(-1) mol/L). At lower doping concentrations below 10(-2) mol/L, PL lifetimes of TPP were relatively constant (similar to 10 ns) and equal to that of TPP in dilute solution. A decrease in PL lifetime was observed at high doping concentration, down to 8 ns at a concentration of 10(-1) mol/L. This observed decrease in PL lifetime of TPP with the increase of TPP concentration was due to the concentration quenching of TPP monomer emission by the TPP dimer/aggregate sites formed at such higher concentrations. The results of concentration quenching in TPP system were compared to that of tetraphenylchlorin system reported earlier. (C) 2005 Springer Science + Business Media, Inc.