Mark Thompson

The efficiency of electroluminescent organic light-emitting devices can be improved by the introduction of a fluorescent dye. Energy transfer from the host to the dye occurs via excitons, but only the singlet spin states induce fluorescent emission; these represent a small fraction (about 25%) of the total excited-state population (the remainder are triplet states). Phosphorescent dyes, however, offer a means of achieving improved light-emission efficiencies, as emission may result from both singlet and triplet states. Although the output coupling of photons can be increased by using shaped substrates, further efficiency improvements require that both singlet and triplet excited states contribute to luminescence. One relatively well studied red emitting phosphorescent dye is PtOEP. Porphine complexes are known to possess long-lived triplet states useful in oxygen detection. The addition of platinum to the porphine ring …