Blue-yellow photoluminescence from Ce3+ → Dy3+ energy transfer in HfO2:Ce3+:Dy3+ films deposited by ultrasonic spray pyrolysis

HfO2 films codoped with Ce3+ and several concentrations of Dy3+ have been processed by the ultrasonic spray pyrolysis technique. Emissions from Dy3+ ions centred at 480 and 575 nm associated with the F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) transitions, respectively, have been observed upon UV excitation via a non-radiative energy transfer from Ce3+ to Dy3+ ions. Such energy transfer via an electric dipole-quadrupole interaction appears to be the most probable transfer mechanism. The efficiency of this transfer increases up to 86 +/- 3% for the film with the highest Dy3+ content (1.9 +/- 0.1 at.% as measured from EDS). The possibility of achieving the coordinates of ideal white light with increasing the concentration of dysprosium is demonstrated. (C) 2010 Elsevier B.V. All rights reserved.