surf final presentation

7/24/2019 SURF Final Presentation

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Electrochromic Inverse Opals

for Smart Windows with Static and ynamic Optica

Transmittance

Christian Lau

Mentors: Julia Greer and Victoria Chernow


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Electrochromic Smart Windows

TiO2 +xLi+ +xe-

SageGlass Smart Window

Siemens Wind Turbine Facility. Hutchinso

LixTiO2

Granqvist, Thin Solid Films, 2014


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Visible and

UV range

Near-IR range

Heat Transfer into Buildings

30-40% of energy consumption

Infrared light a significant sourceof blackbody radiation

Spectra from the American Society

Spectral radiation on Earths su


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Incorporating Photonic Crystals into SmWindows Photonic Crystal:

a low-loss periodic dielectric medium with photonic bandgaps, preventing light frompropagating in certain directions with specified frequencies (Joannopoulos et al. 2008).

Various methods reported for TiO2 inverse opal fabrication via sol-gel coatinwith tunable photonic bandgaps

Kim et al., N


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Evaporative Self Assembly

Born et al., Langm

Solvent evaporation at contact line

causes convective flow into meniscus

Capillary attraction between spheres

causes aggregation


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Smart Window Design

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Transparen

Electrolyte (Li

TiO2

Inverse Opals

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Static photonic bandgap in the near-IR Dynamic electrochromism in the

visible range


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Fabrication Scheme

Substrate SurfaceModification

Evaporative Self

Assembly ofOpal Template

Calcination t

Inverse Opaland Convers

TiBALDH to T

Hatton et al., PNAS, 2010Lu et al., Nanoscale, 2014


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Surface Modification: Titania Deposition

Soda-lime glass

ITO Ti layer

Treat with oxygen plasma a

thermally oxidize Ti at 450 Deposit 5nm layer of Ti by e-

beam evaporation

OH O


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Surface ModificationSoda-lime glass

Sod


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Effect of Surface Modification

ITO

Soda-lime glass

OH OH OH OH


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Vertical Evaporative Deposition

Hatton et al., PNAS, 2010

Sol-Gel Composition:0.14 mL 10% TiBALDH

+ trace EtOH

+ 1.0 mL polystyrene sphere stock solution

in water)

+ 20 mL DI-Water


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Vertical Evaporative Deposition

Curved regions ofmeniscus depositmore uniformly thancenter region


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Calcination/Baking Step

Lu et al., Nanosc

Heat sample to 400 C Surface cracks widen at high

temperatures

400 C

400 C


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Chemical Composition and MolecularStructure of Titania Inverse Opals

Literature raman spectrum taken from RRUFF database

(RRUFFID: R070582)

Rutile Titania

Images by Kinsinger et al., Cr


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Conclusions

Factors affecting inverse opal fabrication Substrate polarity

Deposition method (vertical deposition)

Cracking during baking

Sol Gel methods are promising for fabricating titania inversearrays with the optimal crystal phase


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Future Work

Scalable doctor bladecoating of opal template

Device fabrication andelectrochemical tests

Chen et al. ,ACS Nano, 2012


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Acknowledgements

Vicitoria Chernow and Dr. Greer Greer Group SURFs

Greer Group Grad Students

Student-Faculty Programs

surf final presentation

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