Optical spectroscopy of zinc phosphate films activated with Ce3+, Tb3+ and Mn2+ ions for white LED applications

Abstract Zinc phosphate films doped with Ce3+, Tb3+, Mn2+, Ce3+/Tb3+ and Ce3+/Tb3+/Mn2+ were deposited at 500 °C by the ultrasonic spray pyrolysis technique. Blue emission with color purity of 89.8% is generated from the Ce3+-singly doped film upon 280 nm excitation. The Mn2+-singly doped film emits neutral white light of 4896 K upon 410 nm excitation. The Tb3+-singly doped film excited at 377 nm emits in the green region. Yellowish-green emission is achieved by codoping with Ce3+ and Tb3+ upon Ce3+ excitation at 280 nm, such that Tb3+ is sensitized by Ce3+ through a non-radiative energy transfer with an efficiency of up to 25%. Yellow white emission of 2810 K can be generated from the film triply doped with Ce3+, Tb3+ and Mn2+ upon 280 nm excitation. Tb3+ and Mn2+ being sensitized by Ce3+ through a non-radiative energy transfer with an efficiency of 29%. The energy transfer from Ce3+ to Tb3+ and Mn2+, resulting in yellow white emission, as well the neutral white emission from the Mn2+-singly doped film, make the Mn2+ and Ce3+/Tb3+/Mn2+-doped zinc phosphate films versatile materials that could contribute to the design of efficient UV-blue LED pumped white phosphors.