We are conducting researches on synthesis and applications of photoluminescent nanoparticles with outstanding properties as much as micro-scaled crystals. The materials increase transparency when their sizes are smaller than several hundred nanometer. Transparent and highly functional thin films of nanoparticles on substrate can be obtained by our facile liquid-phase method. Such thin films of nanoparticles with photoluminescent properties have high potentials to be used as a remote phosphor layer in LED lighting and next generation solid state lighting.　Photoluminescent glasses are already used for optical fibers in optical communication as optical amplifiers. We have focused ourselves on material researches for wavelength conversion of solar light to increase efficiency in solar power generation. We have further conducted researches to look for different property conversion properties of photoluminescent nanoparticles and work together with European research institutes for the developments of novel nanomaterials.