The authors report the fabrication of organic light-emitting diodes based on N,N-di-1-naphthalenyl-N,N-diphenyl-[1,1-biphenyl]-4,4-diamine (NPB) that emit via singlet excimer states. When the film deposition rate of NPB is reduced from 17to1nmmin, they observe a reduction in intensity of the photoluminescence peak at 437nm and the evolution of a new, broader peak at 503nm. From optical absorption and time resolved photoluminescence data the authors attribute this new peak to singlet excimer emission. The authors demonstrate green electroluminescence from organic diodes that utilize this effect. The possible morphological variations resulting in the monomer to excimer transition are discussed.

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CCDC 298742 contains the crystallographic data. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre (via www.ccdc.cam.ac.uk/data_request/cif).
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