A novel hydrate-based thin-film phosphor: low-temperature growth process and properties

Abstract

Thin films of barium chloride hydrate doped with cerium were deposited by spray pyrolysis of aqueous solutions. The cathodoluminescence (CL) spectrum consists of two peaks at 443 and 485 nm due to 4f–5d transitions of the cerium ion in thin films without post-heat treatment. The CL depended dramatically on deposition temperature between 250 °C and 500 °C. The phenomenon is directly related to the change of crystallinity and Cl concentration of the thin films. The CL spectra of thin films of BaCl2·2H2O:Ce were compared on various substrates. The relaxation behavior of CL was also observed in thin-film phosphor. Our results indicate that the material studied as thin-film phosphor is unique since it contains water. It seems that the 4f–5d transition in Ce is so energetic that the O–H phonons cannot disturb it, indicating that barium chloride hydrate is a novel host in which Ce has a higher efficiency.