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Versatile multi-layered metal-oxide inverse opal
fabrication for photocatalytic applications
Delphine Lebrun Div. Solid state physics
Dep. Engineering Sciences
Uppsala University
Sweden
Photonic crystals
Engineering choices
Creation of opals
Creation of inverse opals
Controlled Structure
Acknowledgments
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
Blue peafowl
Pavo cristatus
Comb-jellyfish
Beroë cucumis
Beetle
Pachyrrhynchus congestus
pavonius
Morpho Rethenor Opal Jun Xu 2013
Photonic crystals
STRUCTURAL: 2 DIELECTRICS
∆ 𝜀 ≥ 2
Standing waves Frequency gaps
EM(𝑥) depends on 𝜀(𝑥) ∙ 𝐼(𝑥):
Two standing waves have different energies at zone boundaries ↓
Frequency gaps form & prevent photons from propagating ↓
Light totally reflected at these “photonic band gap” (PBG) energies
Photonic crystals
Forbidden region in orange = total reflection
→ Photonic Band Gap (PBG)
Above and Below = light propagates in the structure
Band structure alumina inverse opal (FTDT)
P. Sahoo (KTH) MIT Photonics
Photonic crystals
Engineering choices
Creation of opals
Creation of inverse opals
Controlled structure
Acknowledgments
Photonic crystals
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
With a direct electronic band
gap material
With an indirect electronic
band gap material
Forbidden photonic band
Quench recombination rate
Slow light velocity at higher energy
PBG edge increase electron-hole
pair generation
PBG
PBG
Electronic
band gap
Electronic
band gap
𝑑𝐸
𝑑𝑘= 𝑉𝐺
Engineering choices Ideal position of the PBG for light harvesting
Refractive indices difference
TiO2 Fe2O3 ZnO
Al2O3
Air
H2O
Polystyrene
1.5 1.9 1.0 0.7
1.1 1.6 0.7 0.4
0.9 1.4 0.4 0.1
Engineering choices
Creation of opals
Creation of inverse opals
Controlled structure
Acknowledgments
Photonic crystals
Engineering choices
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
Convective
Evaporation
Beads: PS, silica, PMMA
Substrates: quartz, glass, ITO
Cleaning: Decon90
T= 50°C
25mL beakers
20mL solution
Small angle <10°
Ultra-sonic bath 15 min prior deposition!
Anneal at 85°C for 1h30.
Creation of opals
Periodicity
SHAPE
=
FWHM
SCALE = DEPTH
Photonic Band Gap
Concentration
Temperature
& Humidity
Refractive index
difference
✓ ✓
✓ ✓ ✓
✓
Creation of opals 2 cm
Creation of inverse opals
Controlled structure
Acknowledgments
Photonic crystals
Engineering choices
Creation of opals
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
Atomic Layer Deposition Alumina example
H2O Purge
TMA Purge
´3
´3
0.1 s
0.1 s
120 s
120 s
Creation of inverse opals
85°C 450°C
➊ ➋ ➌
Convective evaporation Atomic Layer Deposition Annealing
Creation of inverse opals
Controlled structure
Acknowledgments
Photonic crystals
Engineering choices
Creation of opals
Creation of inverse opals
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
Filling factor influence Example of 150nm periodicity Al2O3 inverse opal
Blue: 50 cycles
Red: 100 cycles Green: 150 cycles
Black: 200 cycles
245
250
255
260
265
270
275
280
285
290
0 5 10 15 20 25Braggl(nm)
Al2O3thickness(nm)
Opal diameter 148nm
Simulated PGB position
Controlled structure
Multi-layer EDS
SEM
TiO2
Al2O3
Air
Controlled structure
Inverse core-shell structure simulation:
Shift of the Bragg peak vs TiO2 thicknesses
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
325 375 425 475 525
Tra
nsm
itta
nce
λ(nm)
Inverse Alumina 2 nm 5 nm 10 nm
17nm shift 40nm shift 60nm shift
Bragg peak position obtained by FDTD simulation
P. Sahoo (KTH)
Controlled structure
Red: 70 cycles
Blue: 155 cycles
Green : 200 cycles
Black: 250 cycles
ALD Al2O3 : 200 cycles
Experimental shift of the PBG with TiO2 thickness
ALD TiO2
5nm
10nm
15nm 19nm
Controlled structure
Δ = 5 Δ= 11
0
10
20
30
40
50
60
70
0
50
100
150
200
250
300
350
400
450
500
0 2 4 6 8 10 12 14 16 18 20
FW
HM
(n
m)
PB
G (
nm
)
TiO2 thickness (nm)
FWHM vs TiO2 thickness
Simulated
Experimental
PGB position vs TiO2 thickness
Simulated
Experimental
Data analysis of the Al2O3/TiO2 200nm periodicity inverse opals
Controlled structure
Acknowledgments
Photonic crystals
Engineering choices
Creation of opals
Creation of inverse opals
Controlled structure
Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic
applications
Acknowledgments
Supervision: L. Österlund, G. Niklasson, Dep.
Engineering Sciences, and V. Kapaklis, Dep.
Physics and Astronomy, Uppsala University,
Sweden
ALD deposition: M. Fondell and M. Boman, Dep.
Chemistry, Uppsala University, Sweden & M.
Pemble, Tyndall National Institute,
Ireland
Simulations: P. Sahoo and S. Anand, Dep.
Materials Physics, KTH,
Sweden
Thank you for your attention!
I would be glad to answer
questions and take home
remarks.
Delphine
Contact: dele@angstrom
.uu.se