Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Thulium and ytterbium-doped titanium oxide thin films deposited by MOCVD
Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
Conclusion
S. Forissier1,2 , A. Guille2 , H. Roussel1 , C. Jimenez1 , O. Chaix1 , A. Pereira2 , J.-L. Deschanvres1 , B Moine2 1 : Laboratoire des Mat´eriaux et du G´enie Physique / Grenoble-INP, CNRS / MINATEC, 3 parvis Louis N´eel, 38016 Grenoble, France 2 : Laboratoire de Physico-Chimie des Mat´eriaux Luminescents UMR 5620 CNRS / Universit´e Claude Bernard Lyon 1, 10 rue Ada Byron 69622 Villeurbanne, France
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Outline Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Introduction
Introduction Elaboration MOCVD
Elaboration
Characterization
MOCVD
Morphological properties Luminescence properties
Conclusion
Characterization
Morphological properties Luminescence properties
Conclusion
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Context Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Solar spectrum
Introduction Elaboration MOCVD
Available energy for conversion in the solar spectrum.
Characterization Morphological properties Luminescence properties
Conclusion
Potential gains of down-conversion I 10 % under unconcentrated sunlight Badescu et al. Journal of physics D, 2007, 40, 341-352
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Context Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Converting mechanisms
Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
Conclusion
Down-conversion
S´ebastien Forissier
Down-shiing
Up-conversion
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Matrix and ions choice Matrix : TiO2 I Low phonon energy I Easy to grow I Transparency in the visible range
Tm,Yb co-doped TiO2 thin films deposited by MOCVD Introduction Elaboration MOCVD
Characterization Morphological properties
Ions
Luminescence properties
30
TiO2
Energy (103 cm-1)
matrix
Conclusion
{
1
1
20
D2
2 3 3 4
10
3 3
3
0 Yb3+
Tm3+
I
G4 F 2
H5 H4
F5/2
2
H6
I
Ytterbium: emitter 2F5/2 → 2F7/2 Thulium: sensitizer
F7/2
Yb3+
Quantum cutting mechanism between Tm and Yb. Adapted from Richards, Solar energy materials and solar cells, 2006 S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Apparatus Definition AAMOCVD: Aerosol-assisted Metal-Organic Chemical Vapor Deposition
Tm,Yb co-doped TiO2 thin films deposited by MOCVD Introduction Elaboration MOCVD
Description of the apparatus
Characterization Morphological properties Luminescence properties
I I Sample holder
Transducer Solution
I Aerosol Air Carrier
Butanol solvant Acetylacetonate precursors : TiO2 , Yb Tetramethylheptanedionate precursors : Tm
Conclusion
Apparatus schematics S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Apparatus Definition AAMOCVD: Aerosol-assisted Metal-Organic Chemical Vapor Deposition
Tm,Yb co-doped TiO2 thin films deposited by MOCVD Introduction Elaboration MOCVD
Description of the apparatus
Characterization Morphological properties Luminescence properties
I
Sample holder
Transducer Solution
I I
Aerosol Air Carrier
I
Atmospheric pressure synthesis (air gas carrier) Synthesis from 300 ◦C to 600 ◦C Aerosol-assisted Growth rate : 0.1 h−1 to 1 h−1
Conclusion
Apparatus schematics S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Morphological properties Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Surface aspect SEM pictures
Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
Conclusion
(a) top view I I
(b) cross-section
Smooth surface Good density
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Physico-chemicals properties Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Composition
Introduction Elaboration MOCVD
Doping percentage in the film
8 7
I
Tm Yb
6 5 4
I
3 2
Electron microprobe measurements Doping efficiency not linear
Characterization Morphological properties Luminescence properties
Conclusion
1 0 0
2
4
6
8
10
12
14
16
Doping percentage in the solution
Doping efficiency by dopants
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Physico-chemicals properties Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Composition
Introduction Elaboration MOCVD
Doping in the film: RE/(RE+Ti)
1,4
Yb Tm
1,2
I
1 0,8
I
0,6 0,4 0,2
I
0 300
350
400
450
500
550
Deposition temperature (℃)
600
650
Electron microprobe measurements Doping efficiency not linear Optimal doping temperature: 400 ◦C
Characterization Morphological properties Luminescence properties
Conclusion
Optimal doping efficiency
(3 % Tm and 3 % Yb in the solution)
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Physico-chemicals properties Structural properties Influence of substrate temperature
20
25
30
35
40
45
Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
I
Crystallization above 400 ◦C
Conclusion
(105) (211)
(200)
(103) (004) (112)
(101)
Intensity (a.u.)
Si (200)
Anatase JCPDS 00-021-1272 600℃ synthesis 550℃ synthesis 500℃ synthesis 450℃ synthesis 400℃ synthesis 350℃ synthesis
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
50
55
60
Angle (°C)
As-deposited diffractogram
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Physico-chemicals properties Structural properties Influence of annealing temperature
Intensity (a.u.)
Si (200)
Anatase JCPDS 00-021-1272 annealing at 500℃ for 1h annealing at 800℃ for 1h as-deposited at 400℃
I
20
25
30
35
40
45
(105) (211)
(200)
(103) (004) (112)
(101)
I 50
55
60
Tm,Yb co-doped TiO2 thin films deposited by MOCVD Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
Crystallization above 400 ◦C Annealing improves crystallinity
Conclusion
Angle (°C)
Annealing effect on the phases
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Physico-chemicals properties Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Composition
Introduction Elaboration MOCVD
Absorbance (a.u.)
1
Characterization
as deposited annealed 800℃ for 1h
0,8
Morphological properties
0,6 0,4 0,2
OH groups
C-O, C-H groups
0 -0,2 4000
Ti-O anatase 3000
2000
Annealing: I remove organic remnants I Improve crystallisation
Luminescence properties
Conclusion
1000
Wavenumber (cm-1)
FTIR spectrum : annealing effect
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Emission and excitation scans Excitation spectrum
TiO2
matrix
Energy (103 cm-1)
Luminescence properties
30
{
1
1
20
D2
G4
2 3 3 4
F 2
F5/2TiO Tm,Yb co-doped 2 3 H5 3 thin H4films deposited by MOCVD
10
3
0 Yb3+
2
H6
F7/2
3+ TmIntroduction Yb3+
Elaboration MOCVD
Characterization
3
F4→3H6 Tm transition F5/2→2F7/2 Yb transition
Counts (a.u.)
2
I I
Excitation at 330 nm Tm and Yb luminescence
Morphological properties Luminescence properties
Conclusion
Composition: 0.9% Yb, 0.42% Tm 400
500
600
700
800
900
1 000
Wavelength (nm)
Emission spectrum
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Emission and excitation scans Emission spectrum
TiO2
matrix
Energy (103 cm-1)
Luminescence properties
30
{
1
1
20
D2
G4
2 3 3 4
F 2
F5/2TiO Tm,Yb co-doped 2 3 H5 3 thin H4films deposited by MOCVD
10
3
0 Yb3+
2
H6
F7/2
3+ TmIntroduction Yb3+
Elaboration MOCVD
Characterization Morphological properties
Counts (a.u.)
Observation at 973nm (Yb) Observation at 800nm (Tm) Composition: 0.69% Yb, 0.41% Tm
Luminescence properties
I
I 300
350
400
450
500
550
600
Tm and Yb luminescence Absorption through the matrix
Conclusion
Wavelength (nm)
Excitation spectrum
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Luminescence properties Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Decay times
Introduction Elaboration
I
1
I 0,1
0,01
composition : Tm 0,36% | Yb 0,60% | 43µs Tm 0,36% | Yb 1,02% | 39.3µs
0,001
0,0001 0
100
200
Time (µs)
Fluorescence decay
S´ebastien Forissier
300
400
I
Tm: 3F4 → 3H6 Increasing Yb co-doping at Tm constant decreases the lifetime R tI (t)dt τ¯x = R I (t)dt
MOCVD
Characterization Morphological properties Luminescence properties
Conclusion
Transfer rate: 10 % η = 1 − ττ¯x0
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Conclusion Tm,Yb co-doped TiO2 thin films deposited by MOCVD
Results I Thin films doped and crystallised I Energy transfer between Tm and Yb I Yb luminescence under UV illumination
Introduction Elaboration MOCVD
Characterization Morphological properties Luminescence properties
Conclusion
Perspectives I Yield measurements : actual quantum-cutting ? I Ce-doping for increasing absorption I Another host matrix : Y2 O3 I Other ions as sensitizers : Tb, Er
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
Tm,Yb co-doped TiO2 thin films deposited by MOCVD Introduction Elaboration MOCVD
Thank you for you attention.
Characterization Morphological properties Luminescence properties
Conclusion
Support This work has been supported by French Research National Agency (ANR) through Habitat intelligent et solaire photovolta¨ıque program (project MULTIPHOT n°ANR09-HABISOL-009) and the cluster ENERGIES Rhˆone-Alpes, the Carnot institute project MacSiPV.
S´ebastien Forissier
Tm,Yb co-doped TiO2 thin films deposited by MOCVD
August,15th 2011
