TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Ligand: The ligand is bipyridyl, phenanthroline, beta-diketone group compound or their derivatives. Preferred Composition: The organic solution contains water, organic solvent and/or catalyst. Preferred Organic Solvent: The organic solvent is preferably an alcohol, more preferably methanol, ethanol, isopropanol and/or n-butanol and especially isomers or diacetone alcohol.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Element: The rare earth element is europium or terbium. Preferred Alkoxide: The silicon alkoxide is an alkoxide of tertiary ethoxy silane and organic silicone, preferably diethoxydiphenyl silane. Preferred Film Characteristics: The composite thin film is transparent and has uniform thickness of 0.2-0.5 mum. Preferred Process: The solution containing complex and OMS is subjected to condensation polymerization and dehydration. The film formed on the substrate is dried at 50-110degreesC. EXAMPLE - Europium oxide or terbium oxide and ammonium chloride were heated for several hours in nitrogen atmosphere at 200-300degreesC. Excess ammonium chloride was sublimated under vacuum at 400degreesC. The europium or terbium chloride thus obtained was dissolved in ethanol and dropped into ethanol solution of 1,10-phenanthroline to form a precipitate which was then separated, washed by ethanol and vacuum dried to form europium or terbium chloride phenanthroline complex. 75 weight parts (wt.pts) of tertiary ethoxy silane and 75 wt.pts of diphenyldiethoxy silane were added to a mixture consisting of 350 wt.pts of ethanol, 390 wt.pts of isopropyl alcohol, 160 wt.pts of diacetone alcohol, 100 wt.pts of water and 3 wt.pts of hydrochloric acid. Further 0.04 wt.pts of europium or terbium chloride phenanthroline complex was added to the mixture and stirred for 2 hours at room temperature to form OMS coating solution. The solution obtained was coated on quartz glass substrate and dried for 1 hour at 100degreesC to form composite thin film of thickness 0.2 mum. The OMS matrix and phenanthroline ligand showed specific absorption maximas in UV region. Concentration difference in the obtained thin film was not observed and hence was found to be uniform. The composite thin film exhibited specific UV ray excitation fluorescence spectrum which confirmed that the thin film absorbed UV rays efficiently. Light emission was found to be intense against red light. The thin film was found to be effectively used as solar light condensing board in solar battery module.