Understanding the growth of Eu2O3 nanocrystal films made via electrophoretic deposition

Eu2O3 nanocrystals, surface-functionalized with oleic acid, were assembled into transparent thin films via electrophoretic deposition (EPD). Suspended in a non-polar solvent (hexane), the nanocrystals were cast into stable films on both the cathode and the anode. We characterized the nanocrystal films using optical microscopy, energy dispersive spectroscopy and photoluminescence spectroscopy. Scanning electron microscopy and atomic force microscopy provided information regarding the morphology, topology and surface coverage of the films. These homogeneous, densely packed films were composed predominantly of agglomerates (∼15 nm) of the Eu2O3 nanocrystals rather than of individual nanocrystals. Nonetheless, the films possessed low root mean square (RMS) roughness (∼1.4 nm). High transparency of the film in the visible region was facilitated by the dense packing and the small diameter of the agglomerates, which reduced transmission losses due to scattering. The effect of EPD process parameters (applied voltage and nanocrystal concentration) on the growth uniformity and the thickness of the films was examined via surface contact profilometry. We discovered a correlation among the said EPD process parameters, the overall quality and thickness of these transparent films, which provided insight into the mechanisms of the nanocrystal deposition process.