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Thesis defence by Pierre GAFFURI

Published on December 10, 2020
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PhD Defense February 5, 2021
1.30 p.m. - Amphi M001, Building M, ground floor,Grenoble INP Phelma-Minatec
Grenoble INP - Phelma
3 parvis Louis Néel - 38000 Grenoble
Accès : TRAM B arrêt Cité internationale
Free entrance - No registration

New materials for eco-efficient white LEDs: ZnO nanowire-based heterostrcutures and rare-earth-free aluminium borate phosphors

Pierre GAFFURI

Pierre GAFFURI

Keywords:

LED lighting, ZnO nanowires, Aluminoborate phosphors, Semiconductors, Heterostructures, Critical materials

cliquer pour voir la liste des membres du jury/clic here for the jury members

 

Abstract

The widespread implementation of white light-emitting diodes (wLEDs), based on the blue electroluminescence of an LED and the yellow photoluminescence of a phosphor, represents a major opportunity to reduce global energy consumption. The performances of wLEDs are based on materials considered as critical, such as gallium and gallium/indium nitrides for the blue LED, and cerium doped yttrium aluminium garnet for the phosphor. The synthesis of these materials require costly and high-temperature physical and chemical deposition techniques. In this context, new non-critical materials have been studied and manufactured by soft chemistry methods: ZnO nanowires array as n-type semiconductor, and aluminoborate powders as phosphor. On the one hand, the mechanisms of the extrinsic doping and related modification of the growth of ZnO nanowires deposited by chemical bath deposition were investigated, showing the dominant roles of pH and precursor concentrations. Defects and complex defects incorporated in ZnO nanowires, crucial from an application point of view, greatly modify their optical and electrical proprieties. Their epitaxial growth on p-type GaN thin films forms heterojunctions whose electroluminescence properties are evaluated. On the other hand, aluminoborate-based phosphors powders were synthesized by the Pechini method, by substituting yttrium, usually present in the amorphous particles. The optimization of the new chemical compositions and thermal annealing offers a broad emission whose internal quantum luminescence efficiency exceeds 60 %. This study provides a better understanding of the trapping of carbon species, and their role in the luminescence. Eventually, consumer interest in such structures without critical materials and with low embodied energy is measured and offers optimistic prospects for their development

Membres du jury/ Jury members :
 

Prof.

Véronique Jubera

Institut de Chimie de la Matière Condensée de Bordeaux

Rapportrice

Dr

Daniel Lincot

Institut Photovoltaïque d'Ile de France

Rapporteur

Prof.

Gilles Lerondel

Université de Technologie de Troyes

Examinateur

Dr

Rachid Mahiou

Institut de Chimie de Clermont-Ferrand

Examinateur

Prof.

Bruno Masenelli

Institut des Nanotechnologies de Lyon

Examinateur

Dr

Vincent Consonni

Laboratoire des Matériaux et du Génie Physique

Directeur de thèse

Dr

Estelle Appert

Laboratoire des Matériaux et du Génie Physique

Co-encadrante de thèse

Dr

Mathieu Salaün

Institut Néel, Grenoble

Co-encadrant de thèse


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Date of update January 19, 2021

Université Grenoble Alpes