Electrical and Computer Engineering ETDs

Author

Brian Akins

Publication Date

9-15-2014

Abstract

Efficient white LEDs are rapidly taking over many lighting and display applications, because of their improved color rendering and low power requirements. They are attractive replacements for traditional lighting from the point of view of both human perception and energy efficiency. Currently, the most efficient and common LED design consists of a blue LED and a yellow phosphor, which in conjunction produce white light. The LED phosphor is a yellow phosphor made of yttrium aluminum garnet doped with cerium (YAG:Ce). While it does strongly absorb blue light, its external quantum efficiency is only 75% under blue LED excitation at room temperature and it lacks sufficient red spectral content, resulting in cool white light under blue LED excitation. This thesis investigates doped nanophosphors that have unique high temperature emission well above room temperature. A novel technique for colloidal synthesis of ZnSe:Mn/ZnS nanocrystals (NCs) is also presented here, using a growth doping technique that exhibits a bright emission peak at 587 nm with excellent thermal behavior and record high quantum efficiency. The 587 nm peak from the Mn dopant exhibits a record high vi quantum efficiency of 90% with 418 nm excitation light, and has improved stability over previously reported synthesis due to the addition of a ZnS shell.

Keywords

ZnSe:Mn/ZnS, ZnSe:Mn/ZnSeS, InP:Cu/ZnSe, MnSe/ZnSe, Nanocrystal, Nanophosphor, White LED, White light, LED, Light emitting diode, Quantum dot, High Temperature, Very high quantum efficiency

Sponsors

National Science Foundation (NSF), Integrating Nanotechnology with Cell Biology and Neuroscience Integrative Graduate Education and Research Traineeship (INCBN IGERT), Smart Lighting Engineering Research Center (SLERC), Center for Integrated Nanotechnologies (CINT)

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Advisor

Osinski, Marek

First Committee Member (Chair)

Osinski, Marek

Second Committee Member

Feezell, Daniel

Third Committee Member

Smolyakov, Gennady

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