White up-conversion luminescence of NaYF4:Yb3+,Pr3+,Er3+

Photon up-conversion which yields higher energy emission by stacking lower energy photons is possible only with specific rare earth ions. Despite this, it has several potential applications. NaYF4 with Yb3+,Er3+ co-doping has been recognized as one of the most feasible materials for efficient up-conversion luminescence. In this work, the up-conversion luminescence of the Pr3+-Er3+ combination was studied using sensitization by Yb3+. Emission was observed in the visible including blue, green, yellow, orange and red. These are due to the P-3(0,1) -> H-3(4-6),F-3(2-4) and D-1(2) -> H-3(4) (Pr3+) as well as F-2(11/2),S-4(3/2),F-4(9/2) -> I-4(15/2) (Er3+) transitions. Concentration quenching of the Pr + luminescence was observed already with 1 mol-% due to many cross-relaxation processes. With naked eye, the up-conversion luminescence was seen as white light. The CIE chromaticity coordinates are close to those of the standard illuminant F4 which represents warm white. (C) 2013 Elsevier B.V. All rights reserved.