Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications

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1 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Delphine Lebrun Div. Solid state physics Dep. Engineering Sciences Uppsala University Sweden

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3 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled Structure Acknowledgments

4 Photonic crystals Blue peafowl Pavo cristatus Comb-jellyfish Beroë cucumis Beetle Pachyrrhynchus congestus pavonius Opal Jun Xu 2013 Morpho Rethenor

5 Photonic crystals STRUCTURAL: 2 DIELECTRICS ε 2 Frequency gaps Standing waves 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

6 Photonic crystals Band structure alumina inverse opal (FTDT) P. Sahoo (KTH) MIT Photonics Forbidden region in orange = total reflection Photonic Band Gap (PBG) Above and Below = light propagates in the structure

7 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled structure Acknowledgments

8 Engineering choices Ideal position of the PBG for light harvesting With a direct electronic band gap material With an indirect electronic band gap material de dk = V G Electronic band gap PBG Electronic band gap PBG Forbidden photonic band Quench recombination rate Slow light velocity at higher energy PBG edge increase electron-hole pair generation

9 Engineering choices Refractive indices difference TiO 2 Fe 2 O 3 ZnO Al 2 O 3 Air H 2 O Polystyrene

10 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled structure Acknowledgments

11 Creation of opals Beads: PS, silica, PMMA Substrates: quartz, glass, ITO Cleaning: Decon90 Ultra-sonic bath 15 min prior deposition! Anneal at 85 C for 1h30. Convective Evaporation T= 50 C 25mL beakers 20mL solution Small angle <10

12 2 cm Photonic Band Gap Creation of opals SHAPE = FWHM SCALE = DEPTH Concentration Temperature & Humidity Periodicity Refractive index difference

13 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled structure Acknowledgments

14 Creation of inverse opals 0.1 s Atomic Layer Deposition Alumina example TMA Purge s H 2 O 0.1 s Purge s

15 Creation of inverse opals 85 C 450 C ➊ ➋ ➌ Convective evaporation Atomic Layer Deposition Annealing

16 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled structure Acknowledgments

17 Bragg l (nm) Controlled structure Filling factor influence Example of 150nm periodicity Al 2 O 3 inverse opal Simulated PGB position Opal diameter 148nm Al 2 O 3 thickness (nm) Blue: 50 cycles Red: 100 cycles Green: 150 cycles Black: 200 cycles

18 Controlled structure EDS Multi-layer TiO 2 Al 2 O 3 Air SEM

19 Transmittance Controlled structure Inverse core-shell structure simulation: Shift of the Bragg peak vs TiO 2 thicknesses 17nm shift 40nm shift 60nm shift P. Sahoo (KTH) 1 Inverse Alumina 2 nm 5 nm 10 nm Bragg peak position obtained by FDTD simulation λ(nm)

20 Controlled structure Experimental shift of the PBG with TiO 2 thickness 10nm 5nm 15nm 19nm ALD Al 2 O 3 : 200 cycles ALD TiO 2 Red: 70 cycles Blue: 155 cycles Green : 200 cycles Black: 250 cycles

21 PBG (nm) FWHM (nm) Controlled structure Data analysis of the Al 2 O 3 /TiO 2 200nm periodicity inverse opals Δ= 11 Δ = PGB position vs TiO 2 thickness Simulated Experimental TiO 2 thickness (nm) FWHM vs TiO 2 thickness Simulated Experimental

22 Versatile multi-layered metal-oxide inverse opal fabrication for photocatalytic applications Photonic crystals Engineering choices Creation of opals Creation of inverse opals Controlled structure Acknowledgments

23 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

24 Thank you for your attention! I would be glad to answer questions and take home remarks. Delphine Contact: dele@angstrom.uu.se