White light electroluminescence from europium oxide nanocrystal/organic composites

We report the white light emission of hybrid N,N´-diphenyl-N,N´-bis(3-methylphenyl)-1, 1´- biphenyl-4,4´-diamine (TPD) / europium oxide (Eu₂O₃) nanocrystals composite by spin-coating. The organic-inorganic hybrid film consists of Eu₂O₃ nanocrystals, TPD and polymethyl methacrylate (PMMA). The bandwidth of the white light emission spans as wide as 300 nm, which is attributed to the interaction between the organic and inorganic components of the hybrid film. The peak wavelength of the electroluminescence is tuned from 550 nm to 410 nm, when the forward biased voltage increases from 6 V to 9 V. We further investigate the hybrid film by scanning near-field optical microscope and confirm that PMMA improves the film quality and hence the luminescence.