電致變色氧化鎢(WO3)薄膜具有高穿透率變化、高著色效率及高化學穩定性，而受到廣泛的矚目及研究，然而其性質受到薄膜之結晶性、薄膜孔隙率及表面形貌等因素影響，本研究分別利用電子束蒸鍍及電化學陽極化法製備不同結晶度、孔隙率及表面形貌之氧化鎢薄膜，並討論其電致色變性質影響。
研究結果顯示，利用電子束蒸鍍法製備非晶質氧化鎢薄膜，隨電化學循環次數增加，薄膜之電致色變性質亦隨之下降，透過XAS技術及Raman散射光譜發現，於循環過程中，Li+離子與WO3反應產生不可逆相Li2WO4，而使得電致色變性質下降。
於第二部份中，我們利用電子束共蒸鍍技術製備鈮摻雜氧化鎢薄膜，所製備之薄膜外觀具有金屬光澤，對其進行退火熱處理以改善其電致變色性質，結果發現經450 °C熱處理之鈮摻雜氧化鎢薄膜其電致色變性質相較於未經熱處理之薄膜有明顯提升，穿透率變化可由0.6%提升至38.4%，著色效率亦由4 cm2/mC提升至23 cm2 /C，這是由於薄膜之化學計量提升所致。
於第三部份中，我們對濺鍍金屬鎢薄膜進行陽極化處理，及不同溫度450-550 °C熱處理增加薄膜化學計量比，結果金屬鎢薄膜於陽極化處理後，其表面形貌已轉變為多孔微結構，且隨著熱處理溫度增加而使得結晶性增加，但同時燒結及頸縮現象越明顯而降低薄膜孔隙率。於本研究中，500 °C熱處理WO3薄膜具有最佳穿透率變化43.6%及最高著色效率42.8 cm2/C。
在最後一部份中， 對陽極化WO3薄膜進行酸性析出處理，以改變薄膜表面形貌，研究結果發現經酸性析出處理之陽極化WO3薄膜表面形貌由多孔轉變為片狀結構之WO3．2H2O。經400 °C熱處理後，其表面形貌並無明顯變化；當熱處理溫度增加至500 °C，片狀結構崩塌變為顆粒狀。而於電致色變性質測試方面，片狀結構之400 °C熱處理WO3薄膜具有最佳穿透率變化52%及著色效率71 cm2/C。

Electrochromic tungsten trioxide has received much attention due to its high optical modulation, high coloration efficiency, and stable cycling behavior. This thesis is divided into four parts to discuss the effects of microstructure, crystallinity, and morphology on the eletrochromic properties of tungsten trioxide. In the first part, amorphous WO3 films were prepared by electron beam evaporation. The optical transmission spectra showed 13.4% decay of optical modulation after 20 electrochemical cycles. The degradation behaviour of the WO3 films is also observed in electrochemical chronoamperometry measurements. X-ray absorption (XAS) spectroscopy indicates that the absorption energy of the W LIII-edge shifts towards lower energy with the insertion of Li+ ions and electrons. The results of radial distribution functions reveal that the increase in the distance of the W–O bonds is caused by the reduction in W ions. LixWO3 and Li2WO4 are formed at −0.5V and −1.0V, respectively, during electrochemical insertion. The Raman scattering analysis indicates that only two ionic states, W4+ and W6+, exist in the WO3 films, due to excess injection of electrons and Li+ ions. The degradation of the electrochromic properties of the WO3 films during electrochemical cycles is related to the formation of different W ionic states.
In the second part, the Nb-doping WO3 films were deposited by E-beam co-evaporation method using ceramic WO3 targets and metal Nb slugs. The as-deposited Nb-doping WO3 film showed a metallic luster and limited electrochromic properties. By post heat treatment at 450 °C, the Nb-doping WO3 film became stoichiometric and transparent. The GIXRD patterns showed that the Nb-doping WO3 films were amorphous and there is no formation of WNb2O8 compound after 450 °C annealing. The optical modulation was improved from 0.6% to 38.4% and the coloration efficiency was increased from 4 to 23 cm2/C after annealing at 450 °C.
In the third part, porous WO3 films prepared by electrochemical anodization of RF-sputtered metallic tungsten (W) films with different anodization times and annealing temperatures. After anodization, the W films transformed into amorphous structure and showed a brown color. Although the stoichiometry of porous WO3 films were improved by annealing at 450-550 °C, the sintering and necking effects occurred simultaneously. Tungsten oxide films of various morphology, crystallinity, and porosity were obtained by altering the anodization time (20~50 min) and annealing temperature (450~550 °C). The film obtained after 40 minutes of anodization, and that annealed at 500 °C show the best electrochromic performance with optical modulation of 43.6% and coloration efficiency of 42.8 cm2/C.
In the fourth part, tungsten films on ITO glass were anodized into a porous amorphous WO3 morphology at 60 V. The follow-up acidic treatment of the anodized WO3 films in H2SO4 solution transformed the porous morphology into plate-like WO3．2H2O. Glancing incident X-ray diffraction and Raman scattering spectra indicated that the growth of plate-like WO3．2H2O films was caused by a dissolution-precipitation reaction in H2SO4 solution. The plate-like WO3．2H2O transformed into monoclinic WO3 by dehydration at 400 °C, and it collapsed into a dense particle-like one at 500 °C due to the strain of dehydration. Due to its highly porous plate-like morphology, the 400 °C-annealed WO3 film has the highest optical modulation of 52% and coloration efficiency of 71 cm2/C at 633 nm.

[1]吳永豪, 智慧窗與玻璃塗層, 工業材料雜誌, 207 (2004) 136-149,。
[2]Elin Hammarberg, Arne Roos, "Antireflection treatment of low-emitting glazings for energy efficient windows with high visible transmittance", Thin Solid Films, 442 (2003) 222-226.
[3]C.M. Lampert, "Large-area smart glass and integrated photovoltaics", Sol. Energy Mater. Sol. Cells, Vol.76, p.489-499 (2003)
[4]鄧耀宗，’’變色窗技術發展與節能效應’，化工技術，第八卷，第六期，民國九十五年。
[5] C. G. Granqvist, E. Avendano, A. Azens, "Electrochromic Coatings and Devices: Durvey of Some Recent Advances", Thin Solid Films 442 (2003) 201-211.
[6] W. Cheng, E. Baudrin, B. Dunn, J.I. Zink, Synthesis and electrochromic properties of mesoporous tungsten oxide, J. Mater. Chem. 11 (2001) 92-97.
[7] S.H. Baeck, K.S. Choi, T.F. Jaramillo, G.D. Stucky, E.W. McFarland, Enhancement of photocatalytic and electrochromic properties of electrochemically fabricated mesoporous WO3 thin films, Adv. Mater. 15 (2003)1269-1273.
[8] C.G. Granqvist, electrochromic materials: out of a niche, Nat. Mater. 5 (2006) 89-90.
[9] S.H. Lee, R. Deshpande, P.A. Parilla, K.M. Jones, B. To, A.H. Mahan, A.C. Dillon, Crystalline WO3 nanoparticles for highly improved electrochromic applications, Adv. Mater. 18 (2006) 763-766.
[10] G.A. Niklasson, C.G. Granqvist, Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these, J. Mater. Chem. 17 (2007) 127-156.
[11] J. Zhang, J.P. Tu, X.H. Xia, Y. Qiao, Y. Lu, An all-solid-state electrochromic device based on NiO/WO3 complementary structure and solid hybrid polyelectrolyte, Sol. Energy Mater. Sol. Cells, 93 (2009) 1840-1845.
[12] Z.H. Jiao, X.W. Sun, J.M. Wang, L. Ke, H.V. Demir, Hydrothermally grown nanostructured WO3 films and their electrochromic characteristics, J. Phys. D: Appl. Phys. 43 (2010) 285501.
[13] J. Zhang, X.L. Wang, X.H. Xia, C.D. Gu, Z.J. Zhao, J.P. Tu, Enhanced electrochromic performance of macroporous WO3 films formed by anodic oxidation of DC-sputtered tungsten layers, Electrochim. Acta, 55 (2010) 6953-6958.
[14] J. Zhang, J.P. Tu, X. H. Xia, X.L. Wang, C.D. Gu, Hydrothermally synthesized WO3 nanowire arrays with highly improved electrochromic performance, J. Mater. Chem. 21, (2011) 5492-5498.
[15] C.J. Schoot, J.J. Ponjee, H.T. Van-Dam, R.A. Van-Doorn, P.T. Bolwijn, New electrochromic memory display, Appl. Phys. Lett. 23 (1973) 64-65.
[16] P. Bonhôte, E. Gogniat, F. Campus, L. Walder, M. Grätzel, Nanocrystalline electrochromic displays, Displays, 20 (1999) 137-144.
[17] M.J. Wang, G.J. Fang, L.Y. Yuan, H.H. Huang, Z.H. Sun, N.H. Liu, S.H. Xia, X.Z. Zhao, High optical switching speed and flexible electrochromic display based on WO3 nanoparticles with ZnO nanorod arrays’ supported electrode, Nanotechnology, 20 (2009) 185304.
[18] C.M. Lampert, Toward large-area photovoltaic nanocells: experiences learned from smart window technology, Sol. Energy Mater. Sol. Cells, 32 (1994) 307-321.
[19] C.G. Granqvist, Electrochromic oxides: systematics, materials, and applications to smart windows, Renew. Energy, 5 (1994) 141-153.
[20] H. Yoshimura, N. Koshida, Fast electrochromic effect obtained from solid-state inorganic thin-film configuration with a carrier accumulation structure, Appl. Phys. Lett. 88 (2006) 093509.
[21] A. Kraft, M. Rottmann, Properties, performance and current status of the laminated electrochromic glass of Gesimar, Sol. Energy Mater. Sol. Cells, 93 (2009) 2088-2092.
[22] D. Ma, J. Jiang, J. Huang, D. Yang, P. Cai, L. Zhang, S. Huang, An unusual zinc substrate-induced self-construction route to various hierarchical architectures of hydrated tuingsten oxide, Chem. Commun. 46 (2010) 4556-4558.
[23] L. F. Zhu, J. C. She, J. Y. Luo, S. Z. Deng, J. Chen and N. S. Xu, Study of physical and chemical processes of H2 sensing of Pt-coated WO3 nanowire films, J. Phys. Chem. C, 114 (2010) 15504-15509.
[24] X. Zhang, X. Lu, Y. Shen, J. Han, L. Yuan, L. Gong, Z. Xu, X. Bai, M. Wei, Y. Tong, Y. Gao, J. Chen, J. Zhou, Z. L. Wang, Three-dimensional WO3 nanostructures on carbon paper: photoelectrochemical properties and visible light driven photocatalysis, Chem. Commun. 47 (2011) 5804-5806.
[25] M. Sadakane, K. Sasaki, H. Kunioku, B. Ohtani, R. Abe, W. Ueda, Preparation of 3-D ordered macroporous tungsten oxides and nano-crystalline particulate tungsten oxides using a colloidal crystal template method, and their structural characterization and application as photocatalysts under visble light irradiation, J. Mater. Chem. 20 (2010) 1811-1818.
[26] B.D. Alexander, P.J. Kulesza, L. Rutkowska, R. Solarska, J. Augustynski, Metal oxide photoanodes for solar hydrogen production, J. Mater. Chem. 18 (2008) 2298-2303.
[27] C.G. Granqvist, E. Avendano, A. Azens, Electrochromic coatings and devices: survey of some recent advances, Thin Solid Films, 442 (2003) 201–211.
[28] Y. Shen, T. Yamanzaki, Z. Liu, D. Meng, T. Kikuta, N. Nakatani, Influence of effective surface area on gas sensing properties of WO3 sputtered thin films, Thin Solid Films 517 (2009) 2069-2072.
[29] A. Rougier, F. Portemer, A. Que´de´, M. El Marssi, Characterization of pulsed laser deposited WO3 thins films for electrochromic devices, Appl. Surf. Sci. 153 (1999) 1–9.
[30] K.J. Patel, C.J. Panchal, M.S. Desai, P.K. Mehta, An investigation of the insertion of the cations H+, Na+, K+ on the electrochromic properties of the thermally evaporated WO3 thin films grown at different substrate temperatures, Mater. Chem. Phys. 124 (2010) 884–890.
[31] C.M. White, D.T. Gillaspie, E. Whitney, S.-H. Lee, A.C. Dillon, Flexible electrochromic devices based on crystalline WO3 nanostructures produced with hot-wire chemical vapor deposition, Thin Solid Films, 517 (2009) 3596–3599.
[32] W. Wang, Y. Pang, S.N. B. Hodgson, Design and fabrication of bimodal meso-mesoporous WO3 thin films and their electrochromic properties, J. Mater. Chem. 20, (2010) 8591–8599.
[33] W. Cheng, E. Baudrin, B. Dunn, J.I. Zink, synthesis and electrochromic properties of mesoporous tungsten oxide, J. Mater. Chem. 11 (2001) 92-97.
[34] S. Balaji, Y. Djaoued, A.-S. bastien Albert, R. Z. Ferguson, R. Bru¨ning, Hexagonal tungsten oxide based electrochromic devices: spectroscopic evidence for the Li ion occupancy of four-coordinated square windows, Chem. Mater. 21 (2009) 1381–1389.
[35] T. Brezesinski, D. F. Rohlfing, S. Sallard, M. Antonietti, B. M. Smarsly, Highly crystalline WO3 thin films wih ordered 3D mesoporosity and improved electrochromic performance, Small, 2006, 2, (2006) 1203 – 1211.
[36] S.J. Yoo, J.W. Lim, Y.E. Sung, Y.H. Jung, H.G. Choi, D.K. Kim, Fast switchable electrochromic properties of tungsten oxide nanowire bundles, Appl. Phys. Lett. 90 (2007) 173126.
[37] J.M. Wang, E. Khoo, P.S Lee, J. Ma, Synthesis, assembly, and electrochromic properties of uniform rystalline WO3 nanorods, .J. Phys. Chem. C 112 (2008) 14306-14312.
[38] S.H. Beack, T. Jaramillo, G.D. Stucky, E.W. McFarland, Controlled electrodeposition of nanoparticulate tungsten oxide, Nano Lett. 2 (2002) 831-834.
[39] J. R. Platt, "Electrochromism, A Possible Change of Color Producible in Dyes by An Electric Field", J. Chem. Phys. 34 (1961) 862-863.
[40]楊明長, 電致色變系統簡介, 化工 40, No. 2 (1993) 64-67.
[41]林保章,”三氧化鎢薄膜電極之製備及其電致色變性質之研究”,台灣大學化學工程所, 碩士論文, 民國八十七年.
[42] S. K. Deb, "A Novel Electrophotographic System", Appl. Optics 8 (1969) 192-195.
[43] C. M. Lampert, "Smart Switchable Glazing for Solar Energy and Daylight Control", Sol. Energy Mater. Sol. Cells 52 (1998) 207-221.
[44] K. Bange, “Colouration of tungsten oxide films: A model for optically active coatings”, Sol. Energy Mater. Sol. Cells, 58 (1999) 1-131.
[45] B. W. Faughnan, R. S. Crandall, P. M. Heyman, "Electrochromism in WO3 Amorphous Films", RCA Review 36 (1975) 177-197.
[46] S. H. Lee, H. M. Cheong, J. G. Zhang, A. Mascarenhas, D. K. Benson, S. K. Deb, "Electrochromic coloration efficiency of a-WO3 – y thin films as a function of oxygen deficiency", Appl. Phys. Lett. 75, No. 13 (1999) 1541-1543.
[47] C.G. Granqvist, “Handbook of Inorganic Electrochromic materials”, Elsevier, Amsterdam, Lausanne, New York, Oxford, Shannon, Tokyo, p. 181 (1995).
[48] U. Mazur, A. C. Clearly, Infrared and tunneling spectroscopy study of aluminum nitride films prepared by ion-beam deposition, J. Phys. Chem 94, (1990) 189-194.
[49] B. Chapman, "Glow discharge process", John Wiley and Sons, New York, (1980).
[50] G.K. Mor, O.K. Varhese, M. Paulose, K. Shankar, C.A. Grimes, Sol. Energy Mater. Sol. Cells 90 (2006) 2011-2075.
[51] J.M. Macak, H. Tsuchiya, A. Ghicov, K. Yasuda, R. Hahn, S. Bauer, P. Schmuki, Curr. Opin. Solid State Mat. Sci., 11 (2007) 3-18.
[52] N. Özer, , Optical and electrochemical characteristics of sol-gel deposited tungsten oxide films: a comparison, Thin Solid Films 304 (1997) 310-314.
[53] O. Bohnke, G. Frand, M. Fromm, J. Weber, O. Greim, , Depth profiling of W, O and H in tungsten trioxide thin films using RBS and ERDA techniques, Appl. Surf. Sci. 93 (1996) 45-52.
[54] I. Porqueras, E. Bertran, Optical properties of Li+ doped electrochromic WO3 thin films, Thin Solid Films 377/378 (2000) 8-13.
[55] A. Georg, W. Graf, R. Neumann, V. Wittwer, The role of water in gasochromic WO3 films, Thin Solid Films 384 (2001) 269-275.
[56] K. Yoshimura, T. Miki, S. Tanemura, , Electrochromic Properties of Niobium Oxide Thin Films Prepared by DC Magnetron Sputtering, J. Electrochem. Soc. 144 (1997) 2982-2985.
[57] M. A. B. Gomes, L. O. S. Bulhões, S. C. Castro. A. J. Damião, , The Electrochromic Process at Nb2 O 5 Electrodes Prepared by Thermal Oxidation of Niobium, J. Electrochem. Soc. 137 (1990) 3067-3070.
[58] G. Leftheriotis, S. Papaefthimiou, P. Yianoulis, Effect of the tungsten oxidation states in the thermal coloration and bleaching of amorphous WO3 films, Thin Solid Films 384 (2001) 298-306.
[59] H.H. Lu, Effects of oxygen contents on the electrochromic properties of tungsten oxide films prepared by reactive magnetron sputtering, J. Alloy. Compd. 465 (2008) 429-435.
[60] S.H. Lee, H.M. Cheong, J.G. Zhang, A. Mascarenhas, D.K. Benson, S.K. Deb, Electrochromic mechanism in a-WO3-y thin films, Appl. Phys. Lett. 74 (1999) 242-244.
[61] N. Yoshiike, Y. Mizuno, S. Kondo, Behavior of the evaporated WO3 film in Li-salt PC electrolyte, J. Electrochem. Soc. 131 (1984) 2634-2641.
[62] S. Hashimoto, H. Matsuoka, H. Kagechika, Degradation of electrochromic amorphous WO3 film in lithium-salt electrolyte, J. Electrochem. Soc. 137 (1990) 1300-1304.
[63] T. Pauporté, Y. Soldo-Olivier, R. Faure, XAS study of amorphous WO3 formation from a peroxo-tungsten solution, J. Phys. Chem. B 107 (2003) 8861-8867.
[64] A. Kuzmin, J. Purans, X-ray absorption study of local structural change in a-WO3 under colouration, J. Phys.-Condes. Matter 5 (1993) 2333-2340.
[65] O. F. Schirmer, V. Wittwer, G. Baur, G. Brandt, Dependence of WO3 electrochromic absorption on crystallinity, J. Electrochem. Soc. 124 (1977) 749-753.
[66] J. Scarminio, Stress in photochromic and electrochromic effects on tungsten oxide film, Sol. Energy Mater. Sol. Cells 79 (2003) 357-268.
[67]E.O. Zayim, S.H. Lee, C.E. Tracy, J.R. Pitts, S.K. Deb, Comparison of electrochromic amorphous and crystalline tungsten oxide films, Sol. Energy Mater. Sol. Cells 79 (2003) 439-448.
[68] Shigesato, Murayama, Kamimori, Matsuhiro, Characterization of evaporated amorphous WO3 films by Raman and FTIR spectroscopies, Appli. Surf. Sci. 33/34 (1988) 804-811.
[69] J.V. Gabrusenoks, P.D. Chikmach, A.R. Lusis, J.J. Kleperis, G.M. Raman, Electrochromic colour centres in amorphous tungsten trioxide thin films, Solid State Ion. 14 (1984) 25-30.
[70] A. Rougier, A. Blyr, J. Garcia, Q. Zhang, S.A. Impey, Electrochromic W–M–O (M=V, Nb) sol-gel thin films: a way to neutral colour, Sol. Energy Mater. Sol. Cells 71 (2002) 343-357.
[71] T. Ivanova, K.A. Gesheva, M. Kalitzova, B. Marsen, B. Cole, E.L. Miller, Electrochromic behavior of Mo/W oxides related to their surface morphology and intercalation process parameters, Mater. Sci. Eng. B-Adv. Funct. Solid-State Mater. 142 (2007) 126-134.
[72] S.R. Bathe, P.S. Patil, Influence of Nb doping on the electrochromic properties of WO3 films, J. Phys. D-Appl. Phys. 40 (2007) 7423-7431.
[73] S. Hashimoto, H. Matsuoka, Lifetime of Electrochromism of Amorphous  WO3-TiO2 Thin Films, J. Electrochem. Soc. 138 (1991) 2403-2408.
[74] C.O. Avellaneda, L.O.S. Bulhões, Photochromic properties of WO3 and WO3:X (X=Ti, Nb, Ta and Zr) thin films, Solid State Ion. 165 (2003) 117-121.
[75] K. N. Narayanan Unni, Optical characterization of europium diphthalocyanine thin films, Mater. Lett. 57 (2003) 2215-2218.
[76] G. Leftheriotis, S. Papaefthimiou, P. Yianoulis, A. Siokou, Effect of the tungsten oxidation states in the thermal coloration and bleaching of amorphous WO3 films, Thin Solid films 384 (2001) 298–306.
[77] M. Ziolek, I. Nowak, Characterization techniques employed in the study of niobium and tantalum-containing materials, Catal. Today 78 (2003) 543–553.
[78] J. Zhang, J.P. Tu, X. H. Xia, X.L. Wang, C.D. Gu, Hydrothermally synthesized WO3 nanowire arrays with highly improved electrochromic performance, J. Mater. Chem. 21, (2011) 5492-5498.
[79] M.F. Daniel, B. Desbat, J.C. Lassegues, B. Gerand, M. Figlarz, Infrared and Raman study of WO3 tungsten trioxide and WO3xH2O tungsten trioxide hydrates, J. Solid State Chem. 67 (1987) 235-247.
[80] R.R. Kharade, K.R. Patil, P.S. Patil, P.N. Bhosale, Novel microwave assisted sol–gel synthesis (MW-SGS) and electrochromic performance of petal like h-WO3 thin films, Mater. Res. Bull. 47 (2012) 1787–1793.
[81] C. Santato, M. Odziemkowski, M. Ulmannn, J. Augustynski, Crystallographically oriented mesoporous WO3 films: synthesis, characterization, and applications, J. Am. Chem. Soc. 123 (2001) 10639-10649.
[82] Y.C. Nah, A. Ghicov, D. Kim, P. Schmuki, Enhanced electrochromic properties of self-organized nanoporous WO3, Electrochem. Commun. 10 (2008) 1777–1780.
[83] A. Watcharenwong, W. Chanmanee, N.R. de Tacconi, C. R. Chenthamarakshan, P. Kajitvichyanukul, K. Rajeshwar, Anodic growth of nanoporous WO3 films: Morphology, photoelectrochemical reponse and photocatalytic activity for methylene blue and hexvalent chrome conversion, J. Electroanal. Chem. 612 (2008) 112–120.
[84] K.M. Karuppasamy, A. Subrahmmanyam, Studies on the correlation betweenelectrochromic colouration and the relative density of tungsten trioxide (WO3-x) thin films prepared by electron beam evaporation, J. Phys. D-Appl. Phys. 42 (2009) 095301.
[85] E. Washizu, A. Yamamoto, Y. Abe, M. Kawamura, K. Sasaki, Optical and electrochromic properties of RF reactively sputtered WO3 films, Solid State Ion. 165 (2003) 175-180.
[86] C.O. Avellaneda, P.R. Bueno, R.C. Faria, L.O.S. Bulhoes, Electrochromic properties of lithium doped WO3 films prepared by the sol-gel process, Electrochim. Acta 46 (2001) 1977-1981.
[87] M. Deepa, T.K. Saxena, D.P. Singh, K.N. Sood, S.A. Agnihotry, Spin coated versus dip coated electrochromic tungsten oxide films: structure, morphology, optical and electrochromic properties, Electrochim. Acta 51 (2006) 1974-1989.
[88] J. Zhang, J. Tu, X.H. Xia, X.L. Wang, C.D. Gu, Hydrothermally synthesized WO3 nanowire arrays with highly improved electrochromic performance, J. Mater. Chem. 21 (2011) 5492-5498
[89] Y.C. Nah, A. Ghicov, D. Kim, P. Schmuki, Enhanced electrochromic properties of self-organized nanoporous WO3, Electrochem. Commun. 10 (2008) 1777–1780.
[90] S.H. Lee, H.M. Cheong, J.G. Zhang, A. Mascarenhas, D.K. Benson, S.K. Deb, Electrochromic mechanism in a-WO3−y thin films, Appl. Phys. Lett. 74 (1999) 242-244.
[91] F. Amano, M. Tian, B. Ohtani, A. Chen, Photoelectrochemical properties of tungsten trioxide thin film electrodes prepared from facet-controlled rectangular platelets, J. Solid State Electrochem. 16 (2012) 1965-1973.
[92] J.H. Ha, P. Muralidharan, D.K. Kim, Hydrothermal synthesis and characterization of self-assembled h-WO3 nanowires/nanorods using EDTA salts, J. Alloy. Compd. 475 (2009) 446-451.
[93] A.Z. Sadek, H. Zheng, M. Breedon, V. Bansal, S.K. Bhargava, K. Latham, J. Zhu, L. Yu, Z. Hu, P.G. Spizzirri, W. Wlodarski, K. Kalantar-zadeh, High-Temperature Anodized WO3 Nanoplatelet Films for Photosensitive Devices, Langmuir 25 (2009) 9545-9551.
[94] E. Widenkvist, R.A. Quinlan, B.C. Holloway, H. Grennberg, U. Jansson, Synthesis of Nanostructured Tungsten Oxide Thin Films, Cryst. Growth Des. 8 (2008) 3750-3753.
[95] S. Deki, A.B. Béléké, Y. Kotani, M. Mizuhata, Synthesis of tungsten oxide thin film by liquid phase deposition, Mater. Chem. Phys. 123 (2010) 614-619.
[96] W. Li, J. Li, X. Wang, S. Luo, J. Xiao, Q. Chen, Visible light photoelectrochemical responsiveness of self-organized nanoporous WO3 films, Electrochim. Acta 56 (2010) 620-625.
[97] Y. Zhang, J. Yuan, J. Le, L. Song, X. Hu, Structural and electrochromic properties of tungsten oxide prepared by surfactant-assisted process, Sol. Energy Maer. Sol. Cells 93 (2009) 1338-1344.
[98] Y. Baek, Kijung Yong, Controlled Growth and Characterization of Tungsten Oxide Nanowires Using Thermal Evaporation of WO3 Powder, J. Phys. Chem. C 111 (2007) 1213-1218.
[99] M. Ahsan, M.Z. Ahmad, T. Tesfamichael, J. Bell, W. Wlodarski, N. Motta, Low temperature response of nanostructured tungsten oxide thin films toward hydrogen and ethanol, Sens. Actuator B-Chem. 173 (2012) 789-796.
[100] T.G.G. Maffeis, D. Yung, L. LePennec, M.W. Penny, R.J. Cobley, E. Comini, G. Sberveglieri, S.P. Wilks, STM and XPS characterisation of vacuum annealed nanocrystalline WO3 films,Surf. Sci. 601 (2007) 4953-4957.
[101] M. Deepa, A.K. Srivastava, S.N. Sharma, Govind, S.M. Shivaprasad, Microstructural and electrochromic properties of tungsten oxide thin films produced by surfactant mediated electrodeposition, Appl. Surf. Sci. 254 (2008) 2342-2352.
[102] L. Yang, D. Ge, J. Zhao, Y. Ding, X. Kong, Y. Li, Improved electrochromic performance of ordered macroporous tungsten oxide films for IR electrochromic device, Sol. Energy Maer. Sol. Cells 100 (2012) 251-257.