White-light emitting surface-functionalized ZnSe quantum dots: europium complex-capped hybrid nanocrystal

Abstract

A color-tunable emitter comprising Eu complex-capped ZnSe quantum dot (QD) organic–inorganic hybrid nanocrystals (NCs) was simply synthesized by a hot-injection method, plus the addition of an Eu precursor. Hybrid NCs have the emission of both Eu complexes and ZnSe QDs, and they show bluish white light. In the case of composite NCs (Eu/Zn = 1.0), the emission increases up to 174% compared with that of pristine ZnSe QDs. It is due to the sensitization of the Eu complex acting as an antenna, so the energy obtained by the Eu complexes transfers to the ZnSe QDs. In addition, the NCs have a strong excitation band in the near-UV region, which gives them an advantage over wavelength converters for white light-emitting diodes (LEDs). The expected structure of the hybrid NCs was verified by TEM, XRD, and XPS. It features a zinc blende crystal structure identical to the ZnSe QD, along with Eu-based complexes that can be coordinated with the Se ion on the surface of ZnSe QDs. Therefore, new organic–inorganic hybrid luminescent material using the emission of both QDs and lanthanide (Ln) complexes can potentially serve as a light source in white LEDs.