Method for preparing rare-earth metal fluoride REF3 film with trifluoroacetate solution

The invention relates to preparation techniques of optical film materials, display unit materials and solar device materials, particularly a method for preparing a rare-earth metal fluoride REF3 film with a trifluoroacetate solution. Many methods for preparing upconversion fluoride films exist at present, such as ion beam assisted deposition, laser pulse deposition, magnetron sputtering technique, electron beam evaporation technique, sol-gel technique and the like. In the aspect of film preparation, the techniques for preparing oxide upconversion films have been largely researched and reported, and thus, are very mature. However, the film preparation techniques for preparing the fluoride upconversion films are largely limited. By modifying the solution, the water content of the solution is reduced to control the film formation process; and a spin coating method or dip coating method is utilized to obtain the colloid film with bright surface; and heat treatment in an oxygen-free protective atmosphere is utiliz