Novel Phosphors for Luminescence Conversion Intern: Ian Chapman - - PowerPoint PPT Presentation

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Novel Phosphors for Luminescence Conversion Intern: Ian Chapman (ME Major, SBCC) Mentor: Ronan Le Toquin Faculty Advisor: Tony Cheetham UCSB Materials Lab, Summer 2004 Project Funding: Solid State Lighting Device and Display

SLIDE 1

Project Funding: Solid State Lighting Device and Display Center

Novel Phosphors for Luminescence Conversion

Intern: Ian Chapman (ME Major, SBCC)
Mentor: Ronan Le Toquin
Faculty Advisor: Tony Cheetham

UCSB Materials Lab, Summer 2004

SLIDE 2

Phosphor Applications

Luminescence Conversion

– Fluorescent Lighting – Solid State White LEDs

Photon / Electron Detection

– TV Screens – CERN’s L3 Experiment

SLIDE 3

Project Overview

Objective:

– Synthesize novel phosphors for luminescence down-conversion (from Blue/UV to yellow).

Motivation:

– Improve efficiency & lifetime of solid state lighting.

SLIDE 4

Luminescent Down-Conversion

Excitation / Relaxation Energy Diagram Increasing Energy e- e- e- Excitation Energy Emission Energy Internal Energy

Eλ=hc

SLIDE 5

Adapted from: Schlotter, Schmidt, and Schneider, Luminescence conversion of blue light emitting diodes, Appl. Phys. A 64, 417-418 (1997)

Luminescence Converter (Phosphor) GaN / SiC Chip

Luminescence Conversion White LED

Blue Light + Yellow Light White Light

Adapted from: http://science.howstuffworks.com/light6.htm

~ 480 nm ~ 580 nm

Blue

+ Violet / UV Light

SLIDE 6

Research Methods

Approach:

– Design new applicable phosphor materials.

Alter existing PL materials.
Create entirely new phosphors.

– Synthesis

Sol-Gel
Solid State

– Characterization

SLIDE 7

Langbeinite Structure

Ce Space Group: P213 Crystal System: Cubic Cell Parameters: 10.3345(8) (x10-10 m) Composition: K2YZr(PO4)3

SLIDE 8

H2O

(Why) Sol-Gel Synthesis

Adapted from: Brinker and Scherer, Sol Gel Science, Academic Press (1990)

Sol Xerogel Gel Add H3PO4 Crystallization Ceramic Powder Drying M(NO3)3 + H2O M(NO3)3 + H3PO4 MPO4 + 3H2O Mill, Heat to 700oC

SLIDE 9

Powder X-Ray Diffraction

http://www.mrl.ucsb.edu/mrl/centralfacilities/xray/xray-basics/Xray-basics.html#x1 http://www.mrl.ucsb.edu/mrl/centralfacilities/xray/xray-basics/Xray-basics.html#x1

Scale: λCu = 1.54 Å

SLIDE 10

Sintag X2 Theta-Theta Diffractometer

Langbeinite: K2YZr(PO4)3, 2% Ce Doped

SLIDE 11

350 400 450 500 550 600 650 700 750 50 100 150 200 250 300 350 400 450

Intensity (cts) Wavelength (nm)

Luminescence Spectrometer

YAG:Ce (Standard) Sample A Sample B

Excitation: Samples A&B – 380nm YAG:Ce – 460nm

SLIDE 12

Future Research

High efficiency solid state lighting.
Improved synthesis methods.
Materials integration.

SLIDE 13

Adapted from: Schlotter, Schmidt, and Schneider, Luminescence conversion of blue light emitting diodes, Appl. Phys. A 64, 417-418 (1997)

Acknowledgements Acknowledgements

MRL:

MRL: Cheetham Cheetham Group, Joe Doyle Group, Joe Doyle

INSET: Trevor

INSET: Trevor Hirst Hirst, Nick Arnold, Mike , Nick Arnold, Mike Northen Northen

SBCC: Dr. Young, Don Ion

SBCC: Dr. Young, Don Ion

http://science.howstuffworks.co http://science.howstuffworks.co m/light6.htm m/light6.htm Adapted from: Brinker and Scherer, Sol Gel Science, Academic Press (1990)

350 400 450 500 550 600 650 700 750 50 100 150 200 250 300 350 400 450 Intensity (cts) Wavelength (nm)

SLIDE 14

Haaheim, A History of Solid State White Lighting, UCSB (2002)

Relative Efficiencies / Lifetimes: 100 W Incandescent Bulb (~800 h): 17 lu / W Fluorescent Tubes (~10,000 h): 50-70 lu / W White LUCO LED (~100,000 h): 40-50 lu / W (Nichia) 65-74 lu / W (Cree) M OH OH OH P O O O M O M P O O O Sol-Gel White LED Spectra