Electroluminescence from ZnO nanoparticles/organic nanocomposites

The authors report ultraviolet electroluminescence from ZnO nanoparticle-based devices prepared by the phase-segregation technique. The conditions for phase segregation are investigated using confocal microscopy. With proper parameters for phase segregation, the ZnO nanoparticles and N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine: poly(methyl methacrylate) can be separated into two layers upon spin-coating process. The method allows electrons and holes to recombine in the ZnO nanoparticles. The I-V curve shows stable and excellent rectification. For the device with 90nm ZnO nanoparticles, it exhibits a very narrow spectrum with a peak at 392nm and no defect-related emission. The emission peak well corresponds to the ZnO band-gap energy.