Preparation and characterization of photoluminescent ultrathin films based on polyoxometalates

Ultrathin multilayer films of a polyoxotungstoeuropate cluster K15[Eu(BW11O39)2](Eu(BW11)2) and poly(allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer (LbL) self-assembly method. The Eu(BW11)2/PAH multilayer films have been characterized by X-ray photoelectron spectra (XPS) and atomic force microscopy (AFM). UV–VIS measurements reveal regular film growth with each Eu(BW11)2 adsorption. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of 5D0→7FJ. The occurrence of photoluminescent activity confirms the potential for creating luminescent multilayers with polyoxometalates (POMs).