Article ID Journal Published Year Pages File Type
5400038 Journal of Luminescence 2014 8 Pages PDF
Abstract
Upconversion materials have regained interest in recent years due to their potential to enhance the efficiency of solar cells. The research has focused on lanthanide based upconverters, especially Er3+- and Yb3+-doped materials. In this paper we report Ho3+ and Yb3+ upconversion after excitation into the 5I6 Ho3+ state in LiYF4. Infrared excitation into the 5I6 Ho3+ level at 1150 nm induces both visible 5F5→5I8 Ho3+ and near-infrared 2F5/2→2F7/2 Yb3+ upconversion luminescence, around 650 nm and 1000 nm, respectively. The concentration dependence was investigated and the most efficient Ho3+ upconversion was found for LiYF4: 2%Yb3+, 20%Ho3+. Time-resolved spectroscopy as well as temperature dependent measurements were used to unravel the mechanism underlying the upconversion processes. Experimental results and rate equation modeling provides evidence for infrared to near-infrared/visible upconversion mechanisms that are different from those previously reported in the literature.
Related Topics
Physical Sciences and Engineering Chemistry Physical and Theoretical Chemistry
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