Luminescent thin films: Fundamental aspects and practical applications

Inorganic luminescent materials (phosphors) do not absorb visible light and hence they are optically transparent if we could avoid light scattering. Thin films of luminescent materials that are coated on any kinds of substrates are really transparent and have received considerable attention these days. One should know, however, phosphor thin films are usually less bright than powder screens due to the occurrence of multiple internal reflections and light trapping. It is therefore a challenging undertaking to design, synthesize, and utilize luminescent thin films having excellent emission properties. This chapter reviews preparation of luminescent thin films by various kinds of chemical solution deposition methods and their applications. Emphasis is placed on characteristic optical properties of thin films such as transmission, surface Fresnel reflection, total internal reflection, and interference. Applications of luminescent thin films to active waveguides, flat panel displays, X-ray imaging devices, and solar cells are also presented.