Preparation of Eu-doped SrAl2O4 phosphor films from self-assembled polycation/hydroxide multilayer films

The preparation of Eu2+-doped SrAl2O4 phosphor films by a self-assembly approach is investigated. Self-assembled multilayer films of polyethyleneimine (PEI)/mixed (Sr and Eu) hydroxide were prepared on Al2O3 substrates using an alternating layer-by-layer deposition technique. The film formation is based on the electrostatic attraction between negatively charged mixed-hydroxide particles and positively charged Al2O3 substrates adsorbed with PEI. SrAl2O4 films were obtained by calcination of the self-assembled multilayer films at 1300 degrees C in a reducing atmosphere, as revealed by X-ray diffraction analysis. Scanning electron microscopy analysis confirmed that the reaction between the deposited hydroxides and the Al2O3 substrate occurred via calcination to form a dense reaction layer (ca. 2 mu m) on the surface of the substrate. The prepared films exhibited intense green emission at 520 nm when excited at 320 nm, indicating the successful doping of Eu2+ ions in SrAl2O4. Furthermore, the emission intensity increased with an increase in the number of hydroxide deposition cycles. (C) 2008 The Electrochemical Society.