Blue cathodoluminescence from Ba2B5O9Cl:Eu phosphor thin films on glass substrates

Spray pyrolysis was used to deposit thin films of Ba2B5O9Cl:Eu from aqueous solutions containing Eu3+. Blue cathodoluminescence due to the abnormal reduction of Eu3+→Eu2+ in as-grown thin films was observed at the growth temperatures from 140 °C to 500 °C. Significant line narrowing was found as the growth temperature increased. Using either conventional or rapid thermal annealing of thin films in air enhanced the transition of the emission spectrum from several peaks to a sharp single peak. Our results also provide the possibility of tuning the blue emission at temperatures suitable for the use of glass substrates in flat panel applications.