The efficient blue photoluminescence of pyrazolo-[3,4-b]-quinoline derivatives and the energy transfer in polymer matrices

The photophysical properties of a series of pyrazolo-[3,4-b]-quinoline deri vatives have been studied in solution and as dopants in several polymer mat rices (polycarbonate (PC), polystyrene (PS), poly(methyl methacrylate) (PMM A) and poly(N-vinyl carbazole) (PVK)). In solution these materials exhibit a high quantum yield for fluorescence at 450 nm of between 76% and 100%. Th e variation in substitution of the pyrazoloquinoline core of this series of materials has little effect on the photophysical properties in solution or in the polymer films. The materials exhibit little concentration quenching as the photoluminescence efficiencies remain high even at high dopant conc entration. However, there is significant interaction of the dopant with the polymer matrices causing modification of the dopant absorption and excitat ion spectra and faster fluorescence decays. In the case of the PVK matrix t here is evidence for the existence of a rapid energy transfer pathway from the polymer to the dopant. The results show that pyrazoloquinolines are a p romising class of materials for use in optical and optoelectronic applicati ons. (C) 2000 Elsevier Science B.V. All rights reserved.