Phosphorescent iridium(III) cored dendrimers for light-emitting displays

J. C. Ribierre, S. V. Staton, P. L. Burn, I. D.W. Samuel

    Research output: Contribution to journalConference articlepeer-review

    1 Citation (Scopus)

    Abstract

    Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl) iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.

    Original languageEnglish
    Article number63330H
    JournalProceedings of SPIE - The International Society for Optical Engineering
    Volume6333
    DOIs
    Publication statusPublished - Dec 1 2006
    EventOrganic Ligh Emitting Materials and Devices X - San Diego, CA, United States
    Duration: Aug 13 2006Aug 16 2006

    All Science Journal Classification (ASJC) codes

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Computer Science Applications
    • Applied Mathematics
    • Electrical and Electronic Engineering

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