Sol-gel preparation of highly transparent α-Fe2O3 film for the application in red color filter

alpha-Fe2O3 films as inorganic red color filter were synthesized through a simple procedure, epoxide assisted sol-gel route. The sol was prepared through reaction of FeCl2 in boiling ethanol solution with propylene oxide. The films were formed by the dip-coating of sol on substrate, drying and the following annealing steps. The obtained alpha-Fe2O3 films were composed of homogeneous distributed alpha-Fe2O3 nanoparticles with size of 30-50 nm. The film shows strong absorption to the light below 600 nm and high transparency to the red light (87% at 630 nm). As inorganic red color filter, the optic behavior of this film is nearly as same as the organic color filter made of dye.