02100nas a2200169 4500008004100000050001500041245008300056210006900139300001000208490001200218520153600230100002301766700001901789700002301808700002701831856007201858 1997 eng d aLBNL-4009600aAnalysis of Binary Electrochromic Tungsten Oxides with Effective Medium Theory0 aAnalysis of Binary Electrochromic Tungsten Oxides with Effective a50-550 v308-3093 a

Multicomponent oxides are of increasing interest for electrochromic electrodes. To reduce the large number of permutations in composition it would be useful to be able to predict the properties of the mixtures from the pure oxide components. WO3 mixed with V2O5 has been produced by a sol-gel technique in order to increase durability and color neutrality of conventional WO3 electrochromic coatings. Chemical composition was confirmed by Rutherford backscattering spectrometry (RBS). Surface morphology was analyzed by atomic force microscopy (AFM). Electrochromic performance of the films was tested by cyclic voltammetry with in-situ transmission control. Optical constants of vanadium tungsten oxides were determined over the whole solar spectrum. The measurements included variable angle spectroscopic ellipsometry and spectral transmittance and reflectance. An attempt is made to treat doped tungsten oxide as an effective medium consisting of a mixture of WO3 with V2O5. In the clear state, comparison of optical constants and thickness directly determined on the samples yields qualitative agreement with results from effective-medium analysis. The resulting component fraction also agrees as long as the film density does not deviate too much from the linearly interpolated value between the pure components. For the colored state, preferential trapping of electrons at one atom species hinders the application of effective medium theory.

1 avon Rottkay, Klaus1 aÖzer, Nilgün1 aRubin, Michael, D.1 aRichardson, Thomas, J. uhttps://facades.lbl.gov/publications/analysis-binary-electrochromic03663nas a2200133 4500008003900000245009000039210006900129260002200198520316700220100001903387700002103406700002303427856007903450 1996 d00aOptical and Electrochromic Properties of Sol-Gel Deposited Doped Tungsten Oxide Films0 aOptical and Electrochromic Properties of SolGel Deposited Doped  aBerkeleyc01/19963 a

The goal of this study is to investigate the effects of doping of tungsten oxide on its electrochromic properties. The work is directed toward the development of neutral coloring tungsten oxide materials with properties superior to undoped tungsten oxide. Two basic types of sol-gel formulations were used for experimentation. Type 1 used a WOCl4 precursor. Type 2 used a proprietary (Donnelly) tungsten complex precursor. The Type 2 precursor was used only for comparison to Type 1. Doping experiments were performed using the Type 1 chemistry. The dopants studied were Co, Cr, Nb, Ti, V and Y. The range of dopant was 1-12 mole %. Improved electrochromic behavior was observed for tungsten oxide films doped with V and Ti.

Analysis of the films included x-ray diffraction, ellipsometry, cyclic voltammetry and spectrophotometry. X-ray diffraction showed that all films heat treated at temperatures below 300°C were amorphous in structure. The refractive indices for undoped films were measured. We found the n, k values of the Type 1 films to be lower than the Type 2 films. The n and k values were n=1.79 and k=2.8x10-3, and n=2.08 and k=3.6x10-3 at 550 nm, for Type 1 and Type 2 films respectively. Both types of tungsten oxide films showed low absorption and high transparency in the visible range. As expected, we found that the film density, and hence the refractive index and extinction coefficient, depended on coating solution chemistry, hydration, and densification procedures. Undoped Type 1 films showed slightly higher lithium diffusion coefficients (DLi), compared to undoped Type 2 films, DLi=1.36x 10-9 cm2 s-1 and 1.31 x 10-9 cm2 s-1, respectively.

We also noted that the properties of the films could be reproduced for any coating chemistry and densification scheme. The electrochemical and optical behavior were determined by using an in-situ cuvette cell with a 1M LiCl04 / propylene carbonate electrolyte. Cyclic voltammetric measurements showed that doped Type 1 films exhibited electrochemical reversibility beyond 1200 cycles without change in charge capacity. A slight lowering of charge capacity was noted for the undoped films after cycling. The charge capacity for the V doped film was 16.9 mC/cm2 compared to undoped film, 9.6 mC/cm2. Spectrophotometry showed that doped films tended to exhibit a higher absorbance in their colored state compared to undoped films. Considerable improvement in the lithium diffusivity was noted for all the doped films. The greatest change was a factor of 20x for vanadium doping. Doping appeared to increase the cyclic durability of all the tungsten films out to 1200 cycles. Color changes by doping were noted for several dopants. The doped films with the best overall properties were about 8% vanadium and titanium tungsten oxide. The optimum concentration lies in the range of 7 to 12 mol%. The electrochromic color was a neutral brownish-blue for vanadium and grayish-blue for titanium doped tungsten oxide.

1 aÖzer, Nilgün1 aLampert, Carl, M1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/optical-and-electrochromic-properties02176nas a2200181 4500008004100000245005500041210005500096260001200151300001000163490000700173520164100180100002301821700002301844700001701867700001901884700002401903856006701927 1996 eng d00aOptical Indices of Lithiated Electrochromic Oxides0 aOptical Indices of Lithiated Electrochromic Oxides c07/1998 a49-570 v543 a

Optical indices have been determined for thin films of several electrochromic oxide materials. One of the most important materials in electrochromic devices, WO3, was thoroughly characterized for a range of electrochromic states by sequential injection of Li ions. Another promising material, Li0.5Ni0.5O, was also studied in detail. Less detailed results are presented for three other common lithium-intercalating electrochromic electrode materials: V2O5, LiCoO2, and CeO2-TiO2. The films were grown by sputtering, pulsed laser deposition (PLD) and sol-gel techniques. Measurements were made using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The optical constants were then extracted using physical and spectral models appropriate to each material. Optical indices of the underlying transparent conductors, determined in separate studies, were fixed in the models of this work. The optical models frequently agree well with independent physical measurements of film structure, particularly surface roughness by atomic force microscopy. Inhomogeneity due to surface roughness, gradient composition, and phase separation are common in both the transparent conductors and electrochromics, resulting sometimes in particularly complex models for these materials. Complete sets of data are presented over the entire solar spectrum for a range of colored states. This data is suitable for prediction of additional optical properties such as oblique transmittance and design of complete electrochromic devices.

1 aRubin, Michael, D.1 avon Rottkay, Klaus1 aWen, Shi-Jie1 aÖzer, Nilgün1 aSlack, Jonathan, L. uhttps://facades.lbl.gov/publications/optical-indices-lithiated02302nas a2200145 4500008004100000024001200041245008100053210006900134260003000203520178400233100001902017700002102036700002302057856007602080 1996 eng d aUC-160000aSol-Gel Deposited Electrochromic Films for Electrochromic Smart Window Glass0 aSolGel Deposited Electrochromic Films for Electrochromic Smart W aIstanbul, Turkeyc09/19963 a

Electrochrornic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these windows. The sol-gel process offers a low-capital investment for the deposition of these active films. Sol-gel serves as an alternative to more expensive vacuum deposition processes. The sol-gel process utilizes solution coating followed by a hydrolysis and condensation. In this investigation we report on tungsten oxide and nickel oxide films made by the sol-gel process for electrochromic windows. The properties of the sol-gel films compare favorably to those of films made by other techniques. A typical laminated electrochromic window consists of two glass sheets coated with transparent conductors, which are coated with the active films. The two sheets are laminated together with an ionically conductive polymer. The range of visible transmission modulation of the tungsten oxide was 60% and for the nickel oxide was 20%. We used the device configuration of glass/SnO2:F/WO3/polymer/LizNiOxHy/SnO2:F to test the films. The nickel oxide layer had a low level of lithiation and possibly contained a small amount of water. Lithiated oxymethylene-linked poly(ethylene oxide) was used as the laminating polymer. Commercially available Sn02:F/glass (LOF-Tec glass) was used as the transparent conducting glass. We found reasonable device switching characteristics which could be used for devices.

1 aÖzer, Nilgün1 aLampert, Carl, M1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/sol-gel-deposited-electrochromic-001364nas a2200145 4500008004100000245008300041210006900124260001200193300001200205490000700217520087500224100001901099700002101118856007901139 1995 eng d00aElectrochemical Lithium Insertion in Sol-gel Deposited LiNbO3 Films0 aElectrochemical Lithium Insertion in Solgel Deposited LiNbOsub3s c12/1995 a367-3750 v393 a

Inorganic LiNbO3 ion conducting films were prepared by sol-gel process involving two alkoxides, lithium ethoxide and niobium ethoxide. The films were analyzed by ellipsometry, X-ray diffractometry, scanning electron microscopy and impedance spectroscopy. Impedance spectroscopy indicated that the Li+ conductivity values were in the range of 6-8 x 10-7 S cm-1. The morphology and thickness of these films played an important role in the insertion of lithium ions. Spectrophotometric investigation showed that LiNbO3 films exhibit very weak cathodic coloration from 350 to 900 nm spectral region. The previous termelectrochemical and opticalnext term properties clearly indicate that sol-gel deposited LiNbO3 films can be used as lithium ion conducting layers for electrochromic device application.

1 aÖzer, Nilgün1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/electrochemical-lithium-insertion-sol03007nas a2200217 4500008004100000245013800041210006900179260001200248300001200260490000700272520227100279653003002550653002002580653001102600653002302611653002302634100001902657700002102676700002302697856006902720 1995 eng d00aOptical and Electrochemical Characteristics of Niobium Oxide Films Prepared by Sol-Gel Process and Magnetron Sputtering: A Comparison0 aOptical and Electrochemical Characteristics of Niobium Oxide Fil c08/1996 a285-2960 v403 a

Electrochromic niobia (Nb205) coatings were prepared by the sot-gel spin-coating and d.c. magnetron sputtering techniques. Parameters were investigated for the process fabrication of sol-gel spin coated Nb205 films exhibiting high coloration efficiency comparable with that d.c. magnetron sputtered niobia films. X-ray diffraction studies (XRD) showed that the sot-gel deposited and magnetron sputtered films heat treated at temperatures below 450°C, were amorphous, whereas those heat treated at higher temperatures were slightly crystalline. X-ray photoelectron spectroscopy (XPS) studies showed that the stoichiometry of the films was Nb205. The refractive index and electrochromic coloration were found to depend on the preparation technique. Both films showed low absorption and high transparency in the visible range. We found that the n, k values of the sot-gel deposited films to be lower than for the sputtered films. The n and k values were n = 1.82 and k = 3 × 10−3, and n = 2.28 and k = 4 × 10−3 at 530 urn for sot-gel deposited and sputtered films, respectively. The electrochemical behavior and structural changes were investigated in 1 M LiC104/propylene carbonate solution. Using the electrochemical measurements and X-ray photoelectron spectroscopy, the probable electrode reaction with the lithiation and delithiation is Nb2O5 + x Li+ + x e ↔ LixNb205. Cyclic voltametric (CV) measurements showed that both Nb205 films exhibits electrochemical reversibility beyond 1200 cycles without change in performance. “In situ” optical measurement revealed that those films exhibit an electrochromic effect in the spectral range 300 < λ < 2100 nm but remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for 250 nm thick electrodes. Spectroelectrochemical measurements showed that spin coated films were essentially electrochemically equivalent to those prepared by d.c. magnetron sputter deposition.

10aD.C. magnetron sputtering10aelectrochromism10aNiobia10aoptical properties10asol-gel deposition1 aÖzer, Nilgün1 aLampert, Carl, M1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/optical-and-electrochemical02070nas a2200205 4500008004100000245010400041210006900145260002700214520133500241653003201576653002201608653003101630653002601661653002301687653002301710100001901733700002001752700002101772856007101793 1995 eng d00aOptical and Electrochemical Properties of Sol-gel Spin Coated CeO2-TiO2 Films0 aOptical and Electrochemical Properties of Solgel Spin Coated CeO aSan Diego, CAc07/19953 a

The optical and electrochemical properties of sol-gel spin coated Ce02-TiO2 (50% CeO2) films were investigated for electrochrornic applications. The coating solutions were prepared by using mixed organic-inorganic | Ti(OC2H5)4 and Ce(NH4)2 (NO3)6 | precursors. X-ray diffraction studies showed the sol-gel spin-coated films were composed of an amorphous matrix of titanium oxide containing nanocrystallites of cerium oxide. The coating solar transmission value was Ts=0.8 (250 nm thick). The refractive index and the extinction coefficient were derived from transmittance measurements in the UV-VIS-NIR regions. These films had refractive index value of n=2.18 and extinction coefficient value of k=8x10-4 at λ=550 nm. Cyclic voltametric measurements showed reversible electrochemical insertion of lithium ions in a CeO2-TiO2/LiClO4-propylene carbonate electrochemical cell. During cycling the films maintain high optical transmittance. Spectrophotometric and electrochemical investigations performed on CeO2-TiO2 films revealed that these films are suitable as an optically passive counter-electrode in lithium electrochromic devices.

10acerium oxide-titanium oxide10acounter electrode10aelectrochemical properties10aelectrochromic device10aoptical properties10asol-gel deposition1 aÖzer, Nilgün1 aDeSouza, Selmar1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/optical-and-electrochemical-001683nas a2200157 4500008004100000050001400041245009300055210006900148300001200217490000800229520114900237100002301386700002301409700001901432856007401451 1995 eng d aLBL-3804200aOptical Indices of the Tin-doped Indium Oxide and Tungsten Oxide Electrochromic Coatings0 aOptical Indices of the Tindoped Indium Oxide and Tungsten Oxide  a551-5560 v4033 a

Thin films of tin-doped indium oxide are widely used for transparent conductors. One application of In2O3:Sn (ITO) is transparent contacts for electrochromic electrodes. Optical design of electrochromic devices requires knowledge of the optical constants for each layer from the near ultraviolet and visible to the mid infrared. Determination of the optical constants of the electrochromic layer cannot be made in isolation; a complete device or at least a half-cell including a layer of ITO is required to change the optical state of the electrochromic material. Measurements on ITO were made using variable-angle spectral ellipsometry, and spectral transmittance and reflectance. A series of structural models were fit to this data. The problem is complicated because of inhomogeneity in the films, variability in the manufacturing process, and sensitivity to environmental conditions. The spectral dependency was modeled by a single Lorentz oscillator and a Drude free-electron component. This data was then used as the basis for a model to extract the optical constants for a tungsten oxide electrochromic film.

1 avon Rottkay, Klaus1 aRubin, Michael, D.1 aÖzer, Nilgün uhttps://facades.lbl.gov/publications/optical-indices-tin-doped-indium02295nas a2200217 4500008004100000050001500041245013600056210006900192260001200261300001200273490000800285520157600293653002101869653001801890653002301908653003701931100001901968700001801987700002102005856005102026 1995 eng d aLBNL-3900800aPreparation and Properties of Spin-Coated Nb2O5 Films by the Sol-Gel Process for Electrochemical Applications0 aPreparation and Properties of SpinCoated Nbsub2subOsub5sub Films c05/1996 a162-1680 v2773 a

The preparation and properties of Nb2O5 coatings made by the sol-gel process were investigated. The films were deposited by spin coating on In2O3:Sn/glass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized by investigation of the stoichiometry, refractive index, optical transmission, electrochemical behavior, and the microstructure. X-ray diffraction studies showed the films to be amorphous for heat treatments below 450 °C. X-ray photoelectron spectroscopy (XPS) measurement revealed the O:Nb atomic stoichiometry to be 5:2. Cyclic voltammetric measurements showed that the Nb2O5/1 M LiClO4-propylene carbonate system exhibits electrochemical reversibility beyond 1200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb2O5 films exhibit an electrochromic effect in the spectral range 300<λ<2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for a 250 nm thick electrode. XPS spectra indicate that Nb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li+. The bronze coloration is due to a simultaneous injection of electrons and Li+ ions into Nb2O5. The sol-gel-deposited Nb2O5 films are useful for cathodically coloring electrochromic electrodes in electrochromic devices.

10aElectrochemistry10aNiobium oxide10aoptical properties10aX-ray photoelectron spectroscopy1 aÖzer, Nilgün1 aChen, Din-Guo1 aLampert, Carl, M uhttp://dx.doi.org/10.1016/0040-6090(95)08011-201937nas a2200133 4500008004100000050001400041245009400055210006900149260002900218520143800247100001901685700002101704856007801725 1995 eng d aLBL-3852600aSol-Gel Deposited Amorphous Tantalum Oxide and Niobium Oxide Films as Protonic Conductors0 aSolGel Deposited Amorphous Tantalum Oxide and Niobium Oxide Film aToronto, Canadac06/19953 a

In this work we report on the preparation of tantalum oxide and niobium oxide films by the sol-gel method for use as proton ion conductors in electrochromic devices. Measurement of the proton conductivity was derived from impedence spectroscopy measurements. The proton conductivity for Ta2O5 and NbO5 films was 4.6 x 10-6 Scm-1 and 3.2 x 10-7 Scm-1 respectively. The structural and chemical properties of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. These films were found to be amorphous and close to the stoichometry of Ta2O5 and NbO5 respectively. In order to estimate the compatibility of these sol-gel deposited layers as ion conductors for EC devices, we investigated tantalum oxide and niobium oxide films deposited on sputtered WO3 films. Charge balance and coloration characteristics were investigated during voltammetric cycling in a pH 2 liquid electrolyte. Spectral transmittance was measured for colored and bleached conditions. The photopic weighted transmittance change and solar weighted transmittance change were Tp=35.2% - 21.8% and Ts=75.7% - 14.2% for tantala films on tungsten oxide. For niobia on tungsten oxide the values were Tp=85.3% - 35.2% and Ts=75.8% - 28.1%.

1 aÖzer, Nilgün1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/sol-gel-deposited-amorphous-tantalum01160nas a2200157 4500008004100000050001400041245004600055210004500101260002400146300001200170490000700182520069900189100001900888700002100907856007400928 1995 eng d aLBL-3852700aSol-Gel Deposited Electrochromic Coatings0 aSolGel Deposited Electrochromic Coatings aTucson, AZc06/1995 a344-3470 v173 a

Electrochromic devices have increasing application in display devices, switchable minors and smart windows. A variety of vacuum depition technologies have been used to make electrochromic devices. The sol-gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO3, V2O5, TiO2, Nb2O5 and NiOx.

1 aÖzer, Nilgün1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/sol-gel-deposited-electrochromic01880nas a2200181 4500008004100000024001200041245011100053210006900164260002800233520122800261653002701489653002301516653002101539653001901560100001901579700002101598856007901619 1995 eng d aUC-160000aStructural and Optical Properties of Sol-Gel Deposited Proton Conducting Ta2O5 Films0 aStructural and Optical Properties of SolGel Deposited Proton Con aFaro, Portugalc09/19953 a

Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC2H5)5 as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 °C, were amorphous. Films heat treated at higher temperatures were crystalline Ta2O5. The solar transmission values (Ts) of tantala films on glass generally range from 0.8-0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at λ=550 nm increased from n=1.78 to 1.97 with increasing heat treatment from 150 to 450 °C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=1 x 10-3 in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta2O5 films revealed that these films have protonic conductivity of 3.2 x 10-6 S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.

10aelectrochromic devices10aoptical proterties10aproton conductor10atantalum oxide1 aÖzer, Nilgün1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/structural-and-optical-properties-sol01932nas a2200169 4500008004100000050001400041245009300055210006900148300001200217490000700229520136600236100001901602700002101621700002301642700002101665856007601686 1994 eng d aLBL-3852500aCharacterization of Sol-Gel Deposited Niobium Pentoxide Films for Electrochromic Devices0 aCharacterization of SolGel Deposited Niobium Pentoxide Films for a433-4430 v363 a

Niobium pentoxide films, fabricated by the sol-gel process, were spin coated onto conductive indium tin oxide (ITO)/glass, and microscope slides. These films were cycled in a 1M LiClO4 propylene carbonate (PC) solution, and exhibited electrochromic behavior upon the electrochemical insertion (reduction) and extraction (oxidation) of lithium. In-situ optical transmittance measurements were investigated in the ultraviolet/visible/near-infrared wavelength regions (250-2100 nm). Niobium pentoxide films showed reversible optical switching from 320 to 870 nm, but were found electrochromically inactive in the infrared region. Surface analysis using X-ray photoelectron spectroscopy (XPS) indicated little difference in the chemistry of Nb2O5 films as deposited and lithiated LixNb2O5 films, as XPS binding energies of Nb and O showed no appreciable shifts. These films were found to be amorphous by X-ray diffraction. Optical transmittance measurements combined with cyclic voltamograms and XPS spectra, revealed that the electrochromic behavior of these films occurs due to the insertion of Li+ cations into niobium pentoxide films. The bronze coloration of the niobium pentoxide films could make them useful as an electrochromic counter electrodesfor electrochromic devices.

1 aÖzer, Nilgün1 aBarreto, Timothy1 aBuyuklimanl, Temel1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/characterization-sol-gel-deposited01431nas a2200133 4500008004100000050001500041245010100056210006900157520093400226100001901160700001801179700002101197856007901218 1994 eng d aLBNL-3900500aCharacterization of Tantalum Oxide Films Prepared by Sol-Gel Process for electrochemical devices0 aCharacterization of Tantalum Oxide Films Prepared by SolGel Proc3 a

Tantalum oxide films were prepared by sol-gel process using tantalum ethoxide Ta(OC2H5)5. The dependence of deposition conditions (i.e. composition of polymeric solutions and spinning rate) on ionic conductivities for tantalum oxide films were studied. The best results achieved for films fabricated by the spin coating technique were from clear polymeric solutions. These films had low packing density ρ=3.2 g/cm3 and good proton conductivity (about 10-6 Ω-1 cm-1). X-ray photoelectron spectroscopy (XPS) was used for studying the compositions of the tantalum oxide films. We report on the use of tantalum oxide films as ion conductors in devices consisting of WO3/Ta2O5/H+ ion storage polymer structure. We found tantalum oxide to have very good properties for proton device applications.

1 aÖzer, Nilgün1 aHe, Yongxiang1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/characterization-tantalum-oxide-films