Red, green, and blue-emitting Li-doped Y2O3: Re ( Re = Eu3+, Tb3+, or Tm3+ ) film phosphors were coated on sapphire substrates using a sol-gel technique in which yttrium nitrate, metal nitrate (metal = Eu3+, Tb3+, or Tm3+), lithium carbonate, and citric acid were used as the precursor materials. The effect of annealing temperature on Y2O3: Re thin films (similar to 320 nm) and thick films (similar to 1.9 mu m) on sapphire substrates was studied with respect to the structural and cathodoluminescence (CL) properties of the Y2O3: Re film phosphors degrees. The structural and optical trends observed as a function of annealing temperature differed between the thin and thick films. The Y2O3: Re (Re = Eu3+, Tb3+, or Tm3+) red, green, and blue thick films (similar to 1.9 mu m) annealed at 1200 degrees C showed the highest volume and crystallinity of the Y2O3 phase and CL intensity of Li-doped Y2O3: Re (Re = Eu3+, Tb3+, Tm3+) red, green, and blue phosphors. These results for thick-film phosphors are discussed on the basis of the optical properties, such as the CL spectrum, color coordinates, brightness, and longevity. (c) 2007 The Electrochemical Society.