Layer‐by‐layer Multilayer Films Self‐assembled from a Rare‐earth‐containing Poly‐oxometalate Na₉[Eu(W₅O₁₈)₂] and Poly (allylamine hydrochloride) and Their Photoluminescent Properties

Ultrathin multilayer films of a rare‐earth‐containing polyoxometalate Na 9 [Eu(W 5 O 18 ) 2 ] (EW) and poly(allylamine hydrochloride) (PAH) have been prepared by layer‐by‐layer self‐assembly from dilute aqueous solutions. The fabrication process of the EW/PAH multilayer films was followed by UV‐vis spectroscopy and ellipsometry, which show that the deposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayer thickness of ca . 2.1 nm was determined by ellipsometry. In addition, the scanning electron microscopy (SEM) image of the EW/PAH film indicates that the film surface is relatively uniform and smooth. The photoluminescent properties of these films were also investigated by fluorescence spectroscopy.