Efficient Near-Infrared Polymer and Organic Light-Emitting Diodes Based on Electrophosphorescence from (Tetraphenyltetranaphtho[2,3]porphyrin)-platinum(II)

The new metalloporphyrin pt(tptnp); where tptnp = tetraphenyltetranaphtho[2,3]porphyrin, has been prepared and subjected to photophysical and electrooptical device studies. In degassed toluene solution at room temperature Pt(tptnp) features efficient phosphorescence emission with lambda(max) 883 with a quantum efficiency of 0.22. The complex has been used as the active phosphor in polymer and organic light emitting diodes. Polymer light-emitting diodes based on a spin-coated emissive layer consisting of a blend of pt(tptnp) doped in poly(9-vinylcarbazole) and 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole exhibit near-IR emission with lambda(max) 896 nm, with a maximum external quantum efficiency (EQE) of 0.4% and a maximum radiant emittance of 100 mu W/cm(2). Organic light-emitting diodes prepared via vapor deposition of all layers and that feature an optimized multilayer hole injection and electron blocking layer heterostructure with an emissive layer consisting of 4.4'-bis(carbazol-9-yl)biphenyl (CBP) doped with pt(tptnp) exhibit a maximum EQE of 3.8% and a maximum radiant emittance of 1.8 mW/cm(2.) The polynmer and organic ligh-emitting diodes characterized in this study exhibit record high efficiency for devices that emit in the near-IR at lambda > 800nm.