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