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Granqvist, C. G., Arvizu, M. A., Qu, H.-Y., Wen, R.-T. & Niklasson, G. (2019). Advances in electrochromic device technology: Multiple roads towards superior durability. Paper presented at 61st Annual Technical Conference of the Society-of-Vacuum-Coaters (SVC), MAY 05-10, 2018 , Orlando, FL, USA.. Surface & Coatings Technology, 357, 619-625
Open this publication in new window or tab >>Advances in electrochromic device technology: Multiple roads towards superior durability
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2019 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 357, p. 619-625Article in journal (Refereed) Published
Abstract [en]

Most electrochromic (EC) devices must have a service lifetime of many years, and this is particularly so for“smart windows” in buildings with good energy efficiency and indoor comfort. The central part of oxide-based EC devices contains thin films based on W oxide and Ni oxide together with an interposed electrolyte. Depending on operating conditions, these films may show degradation at a slower or faster pace, and means to prevent or reverse this phenomenon, or as a minimum allow reliable lifetime prediction, have been sought ever since the beginnings of EC technology. Here we survey recent endeavors related to EC films of W oxide and Ni oxide and show that (i) electrochemical pretreatment of films in a liquid electrolyte can significantly improve durability, (ii)electrochemical posttreatment in a liquid electrolyte can rejuvenate degraded films, (iii) mixed oxides can have better durability and optical performance than corresponding pure oxides, and (iv) lifetime prediction is possible.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Materials Chemistry
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-369882 (URN)10.1016/j.surfcoat.2018.10.048 (DOI)000455691100083 ()
Conference
61st Annual Technical Conference of the Society-of-Vacuum-Coaters (SVC), MAY 05-10, 2018 , Orlando, FL, USA.
Funder
EU, European Research Council, 267234
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-02-05Bibliographically approved
Arvizu, M. A., Qu, H.-Y., Cindemir, U., Qiu, Z., Rojas González, E. A., Primetzhofer, D., . . . Niklasson, G. (2019). Electrochromic WO3 thin films attain unprecedented durability by potentiostatic pretreatment. Journal of Materials Chemistry A, 7(6), 2908-2918
Open this publication in new window or tab >>Electrochromic WO3 thin films attain unprecedented durability by potentiostatic pretreatment
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 6, p. 2908-2918Article in journal (Refereed) Published
Abstract [en]

Electrochromic windows and glass facades are able to impart energy efficiency jointly with indoor comfort and convenience. Long-term durability is essential for practical implementation of this technology and has recently attracted broad interest. Here we show that a simple potentiostatic pretreatment of sputterdeposited thin films of amorphous WO3-the most widely studied electrochromic material-can yield unprecedented durability for charge exchange and optical modulation under harsh electrochemical cycling in a Li-ion-conducting electrolyte and effectively evades harmful trapping of Li. The pretreatment consisted of applying a voltage of 6.0 V vs. Li/Li+ for several hours to a film backed by a transparent conducting In2O3: Sn layer. Associated compositional and structural modifications were probed by several techniques, and improved durability was associated with elemental intermixing at the WO3/ITO and ITO/glass boundaries as well as with carbonaceous solid-electrolyte interfacial layers on the WO3 films. Our work provides important new insights into long-term durability of ion-exchange-based devices.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-378529 (URN)10.1039/c8ta09621j (DOI)000457893400054 ()
Funder
EU, European Research Council, 267234Swedish Research Council, 821-2012-5144Swedish Research Council, 2017-00646_9Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-03-22Bibliographically approved
Bayrak Pehlivan, I., Arvizu, M. A., Qiu, Z., Niklasson, G. A. & Edvinsson, T. (2019). Impedance Spectroscopy Modeling of Nickel–Molybdenum Alloys on Porous and Flat Substrates for Applications in Water Splitting. The Journal of Physical Chemistry C, 123(39), 23890-23897
Open this publication in new window or tab >>Impedance Spectroscopy Modeling of Nickel–Molybdenum Alloys on Porous and Flat Substrates for Applications in Water Splitting
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2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 39, p. 23890-23897Article in journal (Refereed) Published
Abstract [en]

Hydrogen production by splitting water using electrocatalysts powered by renewable energy from solar or wind plants is one promising alternative to produce a carbon-free and sustainable fuel. Earth-abundant and nonprecious metals are, here, of interest as a replacement for scarce and expensive platinum group catalysts. Ni–Mo is a promising alternative to Pt, but the type of the substrate could ultimately affect both the initial growth conditions and the final charge transfer in the system as a whole with resistive junctions formed in the heterojunction interface. In this study, we investigated the effect of different substrates on the hydrogen evolution reaction (HER) of Ni–Mo electrocatalysts. Ni–Mo catalysts (30 atom % Ni, 70 atom % Mo) were sputtered on various substrates with different porosities and conductivities. There was no apparent morphological difference at the surface of the catalytic films sputtered on the different substrates, and the substrates were classified from microporous to flat. The electrochemical characterization was carried out with linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in the frequency range 0.7 Hz–100 kHz. LSV measurements were carried out at direct current (DC) potentials between 200 and −400 mV vs the reversible hydrogen electrode (RHE) in 1 M NaOH encompassing the HER. The lowest overpotentials for HER were obtained for films on the nickel foam at all current densities (−157 mV vs RHE @ 10 mA cm–2), and the overpotentials increased in the order of nickel foil, carbon cloth, fluorine-doped tin oxide, and indium tin oxide glass. EIS data were fitted with two equivalent circuit models and compared for different DC potentials and different substrate morphologies and conductivities. By critical evaluation of the data from the models, the influence of the substrates on the reaction kinetics was analyzed in the high- and low-frequency regions. In the high-frequency region, a strong substrate dependence was seen and interpreted with a Schottky-type barrier, which can be rationalized as being due to a potential barrier in the material heterojunctions or a resistive substrate–film oxide/hydroxide. The results highlight the importance of substrates, the total charge transfer properties in electrocatalysis, and the relevance of different circuit components in EIS and underpin the necessity to incorporate high-conductivity, chemically inert, and work-function-matched substrate–catalysts in the catalyst system.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Materials Chemistry
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-395176 (URN)10.1021/acs.jpcc.9b02714 (DOI)000489086300017 ()
Funder
EU, Horizon 2020Swedish Research Council, VR-2015-03814Swedish Research Council, VR-2016-03713
Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-12-12Bibliographically approved
Granqvist, C. G., Arvizu, M. A., Qu, H.-Y., Wen, R.-T. & Niklasson, G. (2018). Advances in electrochromic device technology: Multiple roads towards superior durability. In: Proceedings SVC: . Paper presented at Society of Vacuum Coaters 61st Annual Technical Conference, May 5-10, 2018, Orlando, FL, USA. , Article ID 9 pages.
Open this publication in new window or tab >>Advances in electrochromic device technology: Multiple roads towards superior durability
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2018 (English)In: Proceedings SVC, 2018, article id 9 pagesConference paper, Published paper (Refereed)
Abstract [en]

Most electrochromic (EC) devices must have a service lifetime of many years, and this is particularly so for “smart windows” in buildings with good energy efficiency and indoor comfort. The central part of oxide-based EC devices contains thin films based on W oxide and Ni oxide together with an interposed electrolyte. Depending on operating conditions, these films may show degradation at a slower or faster pace, and means to prevent or reverse this phenomenon, or as a minimum allow reliable lifetime prediction, have been sought ever since the beginnings of EC technology. Here we survey recent endeavors related to EC films of W oxide and Ni oxide and show that (i) electrochemical pretreatment of films in a liquid electrolyte can significantly improve durability, (ii) electrochemical posttreatment in a liquid electrolyte can rejuvenate degraded films, (iii) mixed oxides can have better durability and optical performance than corresponding pure oxides, and (iv) lifetime prediction is possible.

National Category
Materials Chemistry
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-368957 (URN)
Conference
Society of Vacuum Coaters 61st Annual Technical Conference, May 5-10, 2018, Orlando, FL, USA
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2019-03-06Bibliographically approved
Arvizu, M. A., Qu, H.-Y., Niklasson, G. A. & Granqvist, C. G. (2018). Electrochemical pretreatment of electrochromic WO3 films gives greatly improved cycling durability. Thin Solid Films, 653, 1-3
Open this publication in new window or tab >>Electrochemical pretreatment of electrochromic WO3 films gives greatly improved cycling durability
2018 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 653, p. 1-3Article in journal (Refereed) Published
Abstract [en]

Electrochromic WO3 thin films have important applications in devices such as smart windows for energy-efficient buildings. Long-term electrochemical cycling durability of these films is essential and challenging. Here we investigate reactively sputter-deposited WO3 films, backed by indium-tin oxide layers and immersed in electrolytes of LiClO4 in propylene carbonate, and demonstrate unprecedented electrochemical cycling durability after straight-forward electrochemical pretreatments by the application of a voltage of 6 V vs. Li/Li+ for several hours.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
National Category
Materials Chemistry Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-352465 (URN)10.1016/j.tsf.2018.02.032 (DOI)000429409800001 ()
Funder
Swedish Research Council, 821-2012-5144]EU, FP7, Seventh Framework Programme, 267234Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2018-12-17
Niklasson, G., Abatte, L., Rojas González, E. A., Arvizu, M. A., Qu, H.-Y. & Granqvist, C. G. (2018). Electrochemical rejuvenation of Tungsten oxide electrochromic thin films: Evidence from impedance spectroscopy. In: 13th International Meeting on Electrochromism, IME-13: Book of Abstracts. Paper presented at 13th International Meeting on Electrochromism, Chiba University, Chiba, Japan, Aug 27-31, 2018 (pp. 11). , Article ID IN-3.
Open this publication in new window or tab >>Electrochemical rejuvenation of Tungsten oxide electrochromic thin films: Evidence from impedance spectroscopy
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2018 (English)In: 13th International Meeting on Electrochromism, IME-13: Book of Abstracts, 2018, p. 11-, article id IN-3Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

A major challenge for energy-efficient smart window technology is to ensure the durability of electrochromic (EC) devices capable of render a service life significantly higher than 20 years. The development of more durable EC materials would also make it possible to increase the transmittance contrast between bleached and colored states without the risk of limiting service life. Recently, it has been shown that degraded EC coatings can be restored to their initial state by electrochemical rejuvenation treatments.1,2 In addition, it was found that tungsten oxide EC films could gain vastly improved durability after extended electrochemical treatments at high applied potentials.3 In this paper we present an attempt to unravel the complex mechanisms behind high potential rejuvenation and durability-enhancing treatments. We study EC amorphous tungsten oxide, which is the most commonly used EC oxide. It is used in most commercial device designs, often in combination with a nickel oxide-based complementary EC layer.

Amorphous tungsten oxide thin films were deposited by sputtering onto conducting indium-tin oxide (ITO) coated glass substrates. Ion intercalation and diffusion in the films were studied by electrochemical impedance spectroscopy measurements in the frequency range 10 mHz-10 kHz and for potentials between 2.0 and 3.3 V vs. Li/Li+, using the film as working electrode in a Li+ containing electrolyte. Measurements were carried out for as-deposited EC tungsten oxide films, degraded and rejuvenated films as well as durability-enhanced WOx films. The impedance data were in good agreement with a Randles-type equivalent circuit containing an anomalous diffusion element.4 In this study we focus on changes at the electrolyte/EC film and EC film/ITO interfaces during degradation and after different electrochemical treatments.

The most notable changes were associated with the high frequency and charge transfer resistances. The high frequency resistance increased significantly during degradation as well as extended rejuvenation treatments; a similar effect was observed in durability-enhanced WOx films. This might indicate compositional or chemical changes in the ITO backing or at the film/ITO interface. The charge transfer resistance associated with the electrolyte/film interface also increased after treatments, but in addition exhibited a strong potential dependence. The appearance of a second high-frequency process after rejuvenation is considered to be more interesting. Possible explanations include an additional adsorption step preceding ion intercalation into the EC film, or alternatively the appearance of a solid-electrolyte interphase layer of the type commonly observed in Li-ion batteries.

Ion diffusion coefficients were not significantly different for rejuvenated EC films as compared to the as-deposited ones. On the other hand degraded films exhibited a completely different impedance response, which could be interpreted as being due to parasitic chemical reactions in the system.

An increased understanding of ageing and rejuvenation processes will facilitate the search for more durable EC materials and preliminary results suggest that interfacial characteristics may influence durability. Eventually, improved EC coatings will be important for large-scale practical application of electrochromic materials, for example in smart windows.

 

 

References

[1]     R.-T. Wen, C.G. Granqvist, G.A. Niklasson, Nature Mater., 14, 996 (2015).

[2]     H.-Y. Qu, D. Primetzhofer, M.A. Arvizu, Z. Qiu, U. Cindemir, C.G. Granqvist, G.A. Niklasson, ACS Appl. Mater. Interf., 9, 42420 (2017).

[3]     M.A. Arvizu, H.-Y. Qu, G.A. Niklasson, C.G. Granqvist, Thin Solid Films, 653, 1 (2018).

[4]     S. Malmgren, S.V. Green, G.A. Niklasson, Electrochim. Acta, 247, 252 (2017).

 

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-368961 (URN)
Conference
13th International Meeting on Electrochromism, Chiba University, Chiba, Japan, Aug 27-31, 2018
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2019-03-07Bibliographically approved
Granqvist, C. G., Arvizu, M. A., Bayrak Pehlivan, I., Qu, H.-Y., Wen, R.-T. & Niklasson, G. A. (2018). Electrochromic materials and devices for energy efficiency and human comfort in buildings: A critical review. Electrochimica Acta, 259, 1170-1182
Open this publication in new window or tab >>Electrochromic materials and devices for energy efficiency and human comfort in buildings: A critical review
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2018 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 259, p. 1170-1182Article, review/survey (Refereed) Published
Abstract [en]

Electrochromic (EC) materials can be integrated in thin-film devices and used for modulating optical transmittance. The technology has recently been implemented in large-area glazing (windows and glass facades) in order to create buildings which combine energy efficiency with good indoor comfort. This critical review describes the basics of EC technology, provides a case study related to EC foils for glass lamination, and discusses a number of future aspects. Ample literature references are given with the object of providing an easy entrance to the burgeoning research field of electrochromics.

National Category
Materials Chemistry Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-350203 (URN)10.1016/j.electacta.2017.11.169 (DOI)000423968600129 ()
Available from: 2018-05-08 Created: 2018-05-08 Last updated: 2018-12-17
Niklasson, G. A., Wen, R.-T., Qu, H.-Y., Arvizu, M. A. & Granqvist, C. G. (2017). Durability of electrochromic films: Aging kinetics and rejuvenation. In: ECS Transactions: . Paper presented at 231st ECS Meeting, New Orleans, May 28 - June 1, 2017 (pp. 1659-1669). Electrochemical Society, 77
Open this publication in new window or tab >>Durability of electrochromic films: Aging kinetics and rejuvenation
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2017 (English)In: ECS Transactions, Electrochemical Society, 2017, Vol. 77, p. 1659-1669Conference paper, Published paper (Refereed)
Abstract [en]

A major challenge for energy-efficient smart window technology is to ensure the durability of electrochromic (EC) devices over aservice life of more than 20 years. In this paper, we report recent results from a fundamental study of the aging kinetics of EC tungsten oxide and nickel oxide thin films and describe electrochemical rejuvenation mechanisms that are able to restore the films to their initial state. The aging kinetics displays an approximate power-law decrease of the charge capacity as a function of cycle number. This decay of charge capacity can be understood in terms of models built on so-called dispersive chemical kinetics. Tungsten oxide and nickel oxide EC films can be rejuvenated by applying a high electrochemical potential or a small constant current. Trapped ions in the bulk or at the surface of the films can be released by these procedures.

Place, publisher, year, edition, pages
Electrochemical Society, 2017
Series
ECS Transactions ; 77 (11)
National Category
Materials Engineering
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-332945 (URN)10.1149/07711.1659ecst (DOI)000432420500151 ()
Conference
231st ECS Meeting, New Orleans, May 28 - June 1, 2017
Funder
Swedish Research Council, 2016-03713EU, European Research Council, 267234
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2018-08-30Bibliographically approved
Qu, H.-Y., Primetzhofer, D., Arvizu, M. A., Qiu, Z., Cindemir, U., Granqvist, C. G. & Niklasson, G. A. (2017). Electrochemical Rejuvenation of Anodically Coloring Electrochromic Nickel Oxide Thin Films. ACS Applied Materials and Interfaces (9), 42420-42424
Open this publication in new window or tab >>Electrochemical Rejuvenation of Anodically Coloring Electrochromic Nickel Oxide Thin Films
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, no 9, p. 42420-42424Article in journal (Refereed) Published
Abstract [en]

Nickel oxide thin films are of major importance as anodically coloring components in electrochromic smart windows with applications in energy-efficient buildings. However, the optical performance of these films degrades upon extended electrochemical cycling, which has hampered their implementation. Here, we use a potentiostatic treatment to rejuvenate degraded nickel oxide thin films immersed in electrolytes of LiClO4 in propylene carbonate. Time-of-flight elastic recoil detection analysis provided unambiguous evidence that both Li+ ions and chlorine-based ions participate in the rejuvenation process. Our work provides new perspectives for developing ion-exchange-based devices embodying nickel oxide.

Keywords
electrochromism, nickel oxide, thin film, electrochemical rejuvenation, ToF-ERDA
National Category
Engineering and Technology Nano Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-336541 (URN)10.1021/acsami.7b13815 (DOI)000418204300003 ()29164852 (PubMedID)
Funder
Swedish Foundation for Strategic Research , SSF-RIF14-0053Swedish Research Council, 821-2012-5144
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2019-02-01Bibliographically approved
Arvizu, M. A., Niklasson, G. A. & Granqvist, C.-G. (2017). Electrochromic W(1-x-y)Ti(x)lo(y)O(3) Thin Films Made by Sputter Deposition: Large Optical Modulation, Good Cycling Durability, and Approximate Color Neutrality. Chemistry of Materials, 29(5), 2246-2253
Open this publication in new window or tab >>Electrochromic W(1-x-y)Ti(x)lo(y)O(3) Thin Films Made by Sputter Deposition: Large Optical Modulation, Good Cycling Durability, and Approximate Color Neutrality
2017 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 5, p. 2246-2253Article in journal (Refereed) Published
Abstract [en]

Tungsten oxide thin films are used in electrochromic devices such as variable-transmittance "smart windows" for energy efficient buildings with good indoor comfort. Two long-standing issues for WO3 thin films are their limited durability under electrochemical cycling and their blue color in transmission. Here, we show that both of these problems can be significantly alleviated by additions of titanium and molybdenum. We found that similar to 300 nm-thick films of sputter deposited W1-x-yTixMoyO3 are able to combine a midluminous transmittance modulation of 0.4 similar to 70% with good color neutrality and durability under extended electrochemical cycling. The Ti content should be similar to 10 at. % in order to achieve durability without impairing transmittance modulation significantly, and the Mo content preferably should be no larger than 6 at. % in order to maintain durability. Hence, our results give clear guidelines for making three-component mixed-oxide thin films that are suitable for electrochromic "smart windows".

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Physical Sciences Chemical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-319529 (URN)10.1021/acs.chemmater.6b05198 (DOI)000396639400039 ()
Funder
EU, FP7, Seventh Framework Programme, 267234
Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2018-08-30
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9885-3161

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