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Smart Windows with Neutral Color, Excellent Durability, and Low Cost using Reversible Metal Electrodeposition versus November 3, 2016 Christopher Barile, Prof. Michael McGehee, Jingye Hou, Dan Slotcavage, Tyler Hernandez, Michael Strand The

SLIDE 1

Smart Windows with Neutral Color, Excellent Durability, and Low Cost using Reversible Metal Electrodeposition

November 3, 2016 Christopher Barile,

Prof. Michael McGehee, Jingye Hou,

Dan Slotcavage, Tyler Hernandez, Michael Strand

versus

SLIDE 2

The Potential of Smart Windows

Dynamically control solar radiation
Buildings used 40% of U.S. electricity

in 2015

20% energy savings for lighting,

cooling, and heating

Car windows, sunglasses

U.S. Energy Information Administration, 2015. View Glass, Energy Savings Guide, http://viewglass.com/assets/pdfs/workplace-white-paper.pdf

SAGE Windows, Chabot College, Hayward, CA

Tinted Transparent

SLIDE 3

Electrochromic Devices

Materials that change

color with voltage

Transition metal
xides

x Li+ + x e- + WO3  LixWO3 colorless blue

Mortimer, R. J. Ann. Rev. Mater. Res. 2011, 41, 241.

SLIDE 4

Drawbacks of Electrochromics

Not color neutral
Absorptive  poor heat management
Expensive due to multiple layers (≥ 4)
Difficult to scale
Cycle life (need > 10,000)

WO3 Electrochromic Boeing 787 Dreamliner

Thakur, V. K. et al. Adv. Mater. 2012, 24, 4071.

SLIDE 5

Reversible Metal Electrodeposition

Only ~20 nm metal required

for complete opacity

Reflective

M+ + e-  M(window) Cathode: Anode: Net: M(frame)  M+ + e- M(frame)  M(window)

Anode: Metal counter electrode around glass Cathode: Transparent conducting substrate on glass Electrolyte containing M+

First Prototypes: M = Cu-Pb, Cu-Ag

SLIDE 6

Metal Deposition from a Cu-Pb System

0.35 V deposition,

0 s 30 s 60 s Visible Infrared ITO on glass working, Pt counter, Ag/AgCl reference electrodes

SLIDE 7

Metal Deposition from a Cu-Pb System

0.35 V deposition,

+0.45 V stripping

0 s 30 s 60 s 90 s 120 s Opaque Transparent Transparent Visible Infrared

Good Resting Stability

ITO on glass working, Pt counter, Ag/AgCl reference electrodes

SLIDE 8

55% Transmission 30% Transmission 5% Transmission

Morphology on Pt-modified ITO

Increasing Deposition Time

200 nm 200 nm 200 nm

SLIDE 9

Smart Window Reliability

Pt-modified ITO/glass electrode Each cycle: -0.35 V for 60 s, +0.45 V for 60 s

Maximum Transmission Minimum Transmission

SLIDE 10

1 Cycle of Deposition: 10 Cycles of Deposition: 1000 Cycles of Deposition:

Morphology on Pt/ITO with Cycling

Reversible Electrochemical Mirror

SLIDE 11

Developing a Gel Electrolyte

Challenges:

Gel viscosity decreases ion

diffusion

Nature of Pt seed layer is

more important Advantages:

Easier device fabrication
Less prone to leaks
Keeps electrolyte confined in

event of accident

SLIDE 12

Anchored Pt Nanoparticles

Good uniformity obtained with anchored Pt

nanoparticles for gel system

( ) ( )

( )

n n

( )

SLIDE 13

Towards Practical Smart Windows

Cu-Ag gel electrolyte
Stable cycling throughout 5,500 cycles

Maximum Transmission Minimum Transmission

SLIDE 14

10 x Speed 5 cm Cycle 1500

SLIDE 15