Abstract

Electrochromic (EC) devices for use as smart windows have a large energy-saving potential when used in the construction and transport industries. When upscaling EC devices to window size, a well-known challenge is to design the EC device with a rapid and uniform switching between colored (charged) and bleached (discharged) states. A well-defined current distribution model, validated with experimental data, is a suitable tool for optimizing the electrical system design for rapid and uniform switching. This paper introduces a methodology, based on camera vision, for experimentally validating EC current distribution models. The key is the methodology’s capability to both measure and simulate current distribution effects as transmittance distribution. This paper also includes simple models for coloring (charging) and bleaching (discharging), taking into account secondary current distribution with charge transfer resistance and ohmic effects. Some window-size model predictions are included to show the potential for using a validated EC current distribution model as a design tool.

© 2011 Optical Society of America

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References

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  1. C. G. Granqvist, Handbook of Inorganic Electrochromic Materials (Elsevier, 1995).
  2. G. A. Niklasson and C. G. Granqvist, “Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these,” J. Mater. Chem. 17, 127–156(2007).
    [CrossRef]
  3. C. M. Lampert, “Large-area smart glass and integrated photovoltaics,” Sol. Energy Mater. Sol. Cells 76, 489–499(2003).
    [CrossRef]
  4. E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).
  5. ChromoGenics AB, EControl-Glas GmbH & Co., Gentex, Sage Electrochromic, Inc., Saint-Gobain, etc.
  6. J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
    [CrossRef]
  7. I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
    [CrossRef]
  8. J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
    [CrossRef]
  9. S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
    [CrossRef]

2007

G. A. Niklasson and C. G. Granqvist, “Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these,” J. Mater. Chem. 17, 127–156(2007).
[CrossRef]

2003

C. M. Lampert, “Large-area smart glass and integrated photovoltaics,” Sol. Energy Mater. Sol. Cells 76, 489–499(2003).
[CrossRef]

2002

J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
[CrossRef]

1999

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
[CrossRef]

1998

S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
[CrossRef]

Bell, J. M.

J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
[CrossRef]

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
[CrossRef]

Clear, R. D.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

DiBartolomeo, D. L.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Evans, G.

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

Fernandes, L. L.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Frost, D.

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

Granqvist, C. G.

G. A. Niklasson and C. G. Granqvist, “Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these,” J. Mater. Chem. 17, 127–156(2007).
[CrossRef]

C. G. Granqvist, Handbook of Inorganic Electrochromic Materials (Elsevier, 1995).

Inkarojrit, V.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Klems, J. H.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Lampert, C. M.

C. M. Lampert, “Large-area smart glass and integrated photovoltaics,” Sol. Energy Mater. Sol. Cells 76, 489–499(2003).
[CrossRef]

Lee, E. S.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Matthews, J. P.

J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
[CrossRef]

Motupally, S.

S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
[CrossRef]

Niklasson, G. A.

G. A. Niklasson and C. G. Granqvist, “Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these,” J. Mater. Chem. 17, 127–156(2007).
[CrossRef]

Selkowitz, S. E.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Skryabin, I. L.

J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
[CrossRef]

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
[CrossRef]

Streinz, C. C.

S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
[CrossRef]

Vogelman, G.

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

Wang, J.

J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
[CrossRef]

Ward, G. J.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Weidner, J. W.

S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
[CrossRef]

Yazdanian, M.

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

Electrochim. Acta

I. L. Skryabin, G. Evans, D. Frost, G. Vogelman, and J. M. Bell, “Testing and control issues in large area electrochromic films and devices,” Electrochim. Acta 44, 3203–3209 (1999).
[CrossRef]

J. Electrochem. Soc.

S. Motupally, C. C. Streinz, and J. W. Weidner, “Proton diffusion in nickel hydroxide—prediction of active material utilization,” J. Electrochem. Soc. 145, 29–34 (1998).
[CrossRef]

J. Mater. Chem.

G. A. Niklasson and C. G. Granqvist, “Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these,” J. Mater. Chem. 17, 127–156(2007).
[CrossRef]

Sol. Energy Mater. Sol. Cells

C. M. Lampert, “Large-area smart glass and integrated photovoltaics,” Sol. Energy Mater. Sol. Cells 76, 489–499(2003).
[CrossRef]

J. Wang, J. M. Bell, and I. L. Skryabin, “The kinetic behaviour of ion transport in WO3 based films produced by sputter and sol-gel deposition: Part I. The simulation model,” Sol. Energy Mater. Sol. Cells 59, 167–183 (1999).
[CrossRef]

Solid State Ion.

J. M. Bell, J. P. Matthews, and I. L. Skryabin, “Modelling switching of electrochromic devices—a route to successful large area device design,” Solid State Ion. 152–153, 853–860(2002).
[CrossRef]

Other

C. G. Granqvist, Handbook of Inorganic Electrochromic Materials (Elsevier, 1995).

E. S. Lee, S. E. Selkowitz, R. D. Clear, D. L. DiBartolomeo, J. H. Klems, L. L. Fernandes, G. J. Ward, V. Inkarojrit, and M. Yazdanian, “Advancement of electrochromic windows,” Publication number CEC-500-2006-052 (California Energy Commission, Public Interest Energy Research, 2006).

ChromoGenics AB, EControl-Glas GmbH & Co., Gentex, Sage Electrochromic, Inc., Saint-Gobain, etc.

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Figures (12)

Fig. 1
Fig. 1

(a) Schematic illustration of an EC device (b) in cross section, (c) the 5 cm × 5 cm EC device, and (d) the 20 cm × 5 cm device. The current collectors are placed 0.5 cm from the active EC surface. The darker parts around the active EC surface in (c) and (d) are sealant materials.

Fig. 2
Fig. 2

Experimental setup as (top) schematic illustration and (bottom) actual picture.

Fig. 3
Fig. 3

EC surface and its transmittance measurement points for a 20 cm × 5 cm EC device with uneven transmittance distribution. The six outer measurement points to the left and right are placed 15 mm from its nearest current collector, and all other measurement points are evenly spaced between these outer points. The WO x current collector outside on left side (not shown in the figure) is the origin point for all measurement points. The darker parts at the very edges are sealant glue and mask material.

Fig. 4
Fig. 4

Transmittance as a function of time when coloring (charging) a 20 cm × 5 cm EC device with 6.0 V versus WO x . The measurement points are placed 15 mm (squares), 37 mm (crosses), 60 mm (circles), 82 mm (asterisks), and 105 mm (triangles) from the WO x current collector.

Fig. 5
Fig. 5

Transmittance as a function of time when bleaching (discharging) a 20 cm × 5 cm EC device with 6.0 V versus WO x . The measurement points are placed 15 mm (squares), 37 mm (crosses), 60 mm (circles), 82 mm (asterisks), and 105 mm (triangles) from the WO x current collector.

Fig. 6
Fig. 6

Comparison between some typical experimentally measured data and the calculated data from the transmittance versus SOC polynomial.

Fig. 7
Fig. 7

Transmittance as a function of time when coloring (charging) a 20 cm × 5 cm EC device with 6.0 V versus WO x . The experimental (markers) and model simulation (solid lines) measurement points are placed 15 mm (squares), 37 mm (crosses), 60 mm (circles), 82 mm (asterisks), and 105 mm (triangles) from the WO x current collector.

Fig. 8
Fig. 8

Transmittance as a function of time when bleaching (discharging) a 20 cm × 5 cm EC device with 6.0 V versus WO x . The experimental (markers) and model simulation (solid lines) measurement points are placed 15 mm (squares), 37 mm (crosses), 60 mm (circles), 82 mm (asterisks), and 105 mm (triangles) from the WO x current collector.

Fig. 9
Fig. 9

Transmittance as a function of time when coloring (charging) a 70 cm × 5 cm EC device with 1.5 V versus WO x . The model simulation measurement points are placed 15 mm (squares), 98 mm (crosses), 180 mm (circles), 263 mm (asterisks), and 345 mm (triangles) from the WO x current collector. The coloration is stopped when the first point reaches 15% transmittance state.

Fig. 10
Fig. 10

Transmittance as a function of time when coloring (charging) a 70 cm × 5 cm EC device with 3.0 V versus WO x The model simulation measurement points are placed 15 mm (squares), 98 mm (crosses), 180 mm (circles), 263 mm (asterisks), and 345 mm (triangles) from the WO x current collector. The coloration is stopped when the first point reaches 15% transmittance state.

Fig. 11
Fig. 11

Transmittance as function of time when coloring (charging) a 70 cm × 5 cm EC device with 6.0 V versus WO x . The model simulation measurement points are placed 15 mm (squares), 98 mm (crosses), 180 mm (circles), 263 mm (asterisks), and 345 mm (triangles) from the WO x current collector. The coloration is stopped when the first point reaches 15% transmittance state.

Fig. 12
Fig. 12

Relation between E e q and f (SOC) used in the models.

Equations (18)

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T 532 nm ( Q ) = 0.00015 Q 3 0.0002 Q 2 + 0.05414 Q + 0.547509 ,
σ 1 d 2 E 1 d x 2 = j ,
σ 2 d 2 E 2 d x 2 = j .
j = S · j 0 { e ( α a F ϕ Σ RT ) e ( α a F ϕ Σ RT ) } ,
ϕ Σ = E 1 E 2 Δ E i R Δ E e q
Δ E i R = j d κ e l ,
Δ E e q = f ( SOC ) = 0.5 + SOC · 1.9 10 3 · e ( 1 SOC + 0.15 )
SOC = q ( x , t ) q max ,
q max = 16 mC / cm 2 .
( σ d E d x = i and σ d i d x = j ) gives σ 1 d 2 E 1 d x 2 = j ,
σ 2 d 2 E 2 d x 2 = j .
x = 0 and t = t i 2 = 0 and E 1 = 0 ,
x = L and t = t i 1 = 0 and E 2 = V app .
d q d t = j ,
q ( x , 0 ) = 0 ( bleached / discharged state , T = 55 % ) ,
q ( x , 0 ) = q c ( colored / charged state , T = 14.5 % )
Δ E i R = j ( d κ el + R i ) ,
R i = 0.05 ( 1 SOC ) .

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