Investigation on the luminescence properties of fluoride phosphors

Abstract

Rare earthbased upconverting phosphors UCPs have attracted much attention due to their unique luminescent properties Compact and inexpensive sources of visible light are mostly in demand at present Rare-earth RE fluoride phosphors are used to convert nearinfrared NIR to visible light by upconversion UC phenomena to make highperformance displays In the present study UC is a sequential form of nonlinear two/three-photon absorption in which a sensitizer absorbs two or more low energy photons and transfers its energy to activator which emits light in the visible range Some of the UC emitter s most appealing characteristics for displays are a wide colour range with saturated colours high brightness operation without damage to the emitters long lifetimes and efficiencies comparable to those of existing technologies Other advantages comprise ease of fabrication and the changeability of operating modes The aim of the study is to improve the upconversion emission intensities of Yb3Er3 codoped phosphors by varying the host As the distance between the sensitizer and the activator significantly affects the energy transfer efficiency different strategies are explored to change the local symmetry around the doped lanthanides One important strategy is the intentional codoping of active (participate in energy transfer or passive do not participate in energy transfer impurities into the host matrix The role of doped passive impurities K in enhancing the UC as well as in influencing the intense UV UC emission through excess sensitization active impurity are studied Additionally the effects of both active and passive impurity doping on the morphological and optical performance of UCPs are investigated newline