(Invited, Digital Presentation) Novel Technology for Halide Phosphors

Abstract

Many people believe that an ionic-diffusion in an ionic crystal is very slow around room temperature. Therefore, a conventional solid-state reaction (SSR) method requires a high temperature to synthesize the ceramic materials. Synthesis of morphology controlled phosphors can be categorized in two ways namely, chemical and physical methods. Various methods such as the sol-gel, hydro-thermal, or the polymerized complex methods are usually used to synthesize phosphor materials. However, these methods require expensive and special experimental equipment, raw materials, or solvents.In order to perform inexpensive mass-production for new phosphor materials, we have applied novel soft chemical synthesis technique, water-assisted solid-state reaction (WASSR) method. The WASSR method is very simple and can synthesize nano-materials just by storing or mixing raw materials added a small amount (typically 10wt%) of water at low temperature below 500 K. Typical particle sizes (10 - 100 nm) of the samples prepared by the WASSR method were smaller than that (2 - 10 micrometer size) of the sample prepared by the SSR method. The most probable mechanism is new type water accelerated solid acid-base reaction on the surface. We successfully synthesized various phosphor materials ((Cs,Rb)VO3, YVO4:Eu, Ba2SiO4:Eu, LaPO4:Ce,Tb) by the WASSR method. In this study, we report the synthesis of non-oxide halide phosphors (CsPbX3, K2SiF6:Mn).For example, a stoichiometric mixture of CsBr, PbCl2 was mixed for the WASSR synthesis of CsPbBr3 quantum dot phosphor. Then, a small amount (10 wt%) of water was added to the mixture and mixed using mortar for 1 min to synthesize a single phase of CsPbBr3. The XRD pattern of the products are in good agreement with that of single phase CsPbBr3. The QD dispersed hexane solution shows strong green emission under the excitation of UV light. Our proposed WASSR synthesis technique is a powerful tool for rapid screening and mass-production of phosphor materials.AcknowledgmentThis research was partly supported by the Ministry of Trade, Industry and Energy(MOTIE) and Korea Institute for Advancement of Technology(KIAT) through the International Cooperative R&D program(P0006844_Development of color conversion nanocrystal luminescence materials for next generation display).