NOVELTY - A rare earth co-doped crystalline light emitting material preparing method involves dissolving a rare earth oxide in concentrated hydrochloric acid to obtain clear solution. The pH of the clear solution is adjusted with saturated salt solution. The resultant solution is added with precipitating agent to completely precipitate the rare earth oxide. The precipitate is filtered and washed. The washed precipitate is calcined to obtain calcined powder. The calcined powder is doped in titanium dioxide colloid.    USE - Method for preparing a rare earth co-doped crystalline light emitting material for use in a titanium dioxide colloid hybrid solar battery.    ADVANTAGE - The method enables preparing the synthetic rare earth doped crystalline light emitting material with improved photoelectric conversion efficiency.    DETAILED DESCRIPTION - A rare earth co-doped crystalline light emitting material preparing method involves dissolving a rare earth oxide in concentrated hydrochloric acid to obtain clear solution. The pH of the clear solution is adjusted with saturated salt solution. The resultant solution is added with precipitating agent to completely precipitate the rare earth oxide. The precipitate is filtered and washed. The washed precipitate is calcined to obtain calcined powder. The calcined powder is doped in titanium dioxide colloid, followed by using n-type semiconductor titanium dioxide nanomaterial as anode, passing light through a hole transport layer comprising PEDOT and PSS and electrons recombine to form electron-hole on the material to obtain finished product. An INDEPENDENT CLAIM is also included for a method for preparing a titanium dioxide colloid hybrid solar battery, which involves taking yttrium oxide powder and rare earth oxide powder at a mole ratio of 95:5 to obtain mixture, followed by dissolving the mixture in a concentrated hydrochloric acid, stirring the mixture until the clear solution to be obtained, adjusting a pH value of sodium hydroxide solution to neutral range, preparing a potassium metasilicate solution by using co-precipitation technique, adding a precipitator slowly into the potassium metasilicate solution until white precipitate to be obtained, filtering and washing the white precipitate, performing doping operation for 150 minutes, obtaining titanium dioxide colloid, forming multiple holes on an n-type semiconductor and coating a conductive layer on an FTO conductive glass to obtain finished product.