Date of Award

2019

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Applied Physics (MS)

Administrative Home Department

Department of Physics

Advisor 1

Jae Yong Suh

Committee Member 1

Patricia Heiden

Committee Member 2

Jacek Borysow

Abstract

There is no debate of the affect that solid-state lighting has had on the world we live in. Throughout the centuries, lighting has continued to improve from kerosene lanterns to white light emitting diodes. Even though lighting today is sufficient there is still much room to improve color rendering index and efficiency. An active area of research to improve today's lighting technology is by doping inorganic phosphors with luminescent ion centers. There have been numerous reports of inorganic phosphors showing a variety of emission color and luminescence. In this thesis we discuss two new inorganic phosphors codoped with Eu2+ and Mn2+ and the energy transfer mechanism between the two. The phosphor Na(Sr,Ba)PO4 shows dual emission peaks with Eu2+ emitting blue light, and Mn2+ emitting red-orange light. In comparison, the phosphor Ba2Mg(BO3)2 shows an overlapped emission from both Eu2+ and Mn2+ in the red-orange region. Energy transfer can occur when there is spectral overlap between the emission of Eu2+ and the absorption of Mn2+. In this study, we compared the energy transfer when emission of Eu2+ is Stokes-shifted by the host material to an overlapping region of Mn2+ emission as seen in Ba2Mg(BO3)2. With photoluminescence and time resolved photoluminescence measurements, we characterized the effects of the host material on the luminescence centers and the energy transfer mechanism. The data clearly suggests that the energy transfer efficiency increases for a specific overlap between the energy levels as seen in Ba2Mg(BO3)2, compared to the greater overlap seen in Na(Sr,Ba)PO4.

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