Transparent luminescent layers via ionic liquid-based approach to LaPO4:RE (RE = Ce, Tb, Eu) dispersions

Transparent layers containing the highly luminescent nanophosphors LaPO4:Ce,Tb and LaPO4:Eu are realized by ink-jet printing on standard transparencies and black paper. The luminescent material is non-agglomerated, 15 nm in size, and applied as a dispersion in ethanol for printing. The structured layers exhibit intense green (LaPO4:Ce,Tb) or red (LaPO4:Eu) emission. While printing on overhead transparencies, an optical transmission of about 90% is realized. This value, in fact, is limited due to the performance of the underlying polymer material. A microwave-assisted synthesis in ionic liquids as a novel concept of synthesis is prerequisite to gain the nanoscale phosphor materials.