臺灣博碩士論文加值系統

利用電泳法將奈米顆粒TiO2沉積於鈦金屬基板製備成染料敏化太陽能電池中的光電極，其中包含多次的電泳沉積與乾燥。經過高溫鍛燒之後，能製備出奈米顆粒緊密堆疊的薄膜。
對於背照式的染料敏化太陽能電池而言，分別比較(1)相對電極上白金的厚度、(2)工作電極的鍛燒溫度、(3)電解質裡含碘的濃度、(4)二氧化鈦層的厚度、(5)在鈦金屬基板與穿透層之間加入散射層等五項參數，找出最佳條件，並以X繞射、掃描式電子顯微鏡、紫外光-可見光吸收光譜儀、IMPS、IMVS和交流阻抗頻譜去分析，達到約7%的光電轉換效率。

We use electrophoretic deposition (EPD) method to deposite TiO2 nanoparticles on the Ti foil, consisting of repetitive short-term depositions with intermediate drying to prepare nanocrystalline TiO2 films for dye-sensitized solar cells (DSSCs). After calcination, the EPD TiO2 films exhibited a more compact TiO2 network.
The effect of five factors, i.e., (i) the thickness of platinum film sputtered on the counter electrode, (ii) sintering temperature of TiO2-coated Ti foil, (iii) the concentration of iodine in the electrolyte, (iv) thickness of TiO2 film, (v) the effect of the scattering layer deposited between the Ti foil and the transparent layer are reported for the photovoltaic performance of a back-illuminated flexible dye-sensitized solar cell with Ti foil substrate for the TiO2 layer.
Optimization of these five factors yields a solar cell conversion efficiency 7%. X-ray diffraction (XRD), scanning electron micrographs (SEM), UV-Visible spectrophotometer, intensity-modulated photocurrent spectroscopy (IMPS), intensity-modulated photovoltage spectroscopy (IMVS) and electrochemical impedance spectroscopy (EIS) are used to substantiate the explanation.

中文摘要..................................................................................................... I
Abstract....................................................................................................... II
誌謝............................................................................................................. III
目錄............................................................................................................. V
圖目錄......................................................................................................... IX
表目錄......................................................................................................... XIV


第一章 緒論………..………………………………...………… 1
1-1 前言……………………………………………………...………… 1
1-2 半導體簡介……………………………………………………… 3
1-3 太陽能電池……………………………………………………….. 6
1-4 電泳沉積(Electrophoretic deposition) …………………………… 7
1-5 研究動機與目的……………………………………………….…. 9
第二章 文獻回顧與理論說明..................................................... 10
2-1 光伏效應(Photovoltaiceffect)……………..………………………. 10
2-2 染料敏化太陽能電池....................................................................... 12
2-2.1 裝置構造…………………………………............................... 12
2-2.2 工作原理................................................................................... 13
2-2.3 逆反應(back reaction)............................................................... 14
2-3 奈米結晶多孔膜電極....................................................................... 16

2-4 染料敏化劑(dye sensitizer).............................................................. 20
2-5 電解質(electrolyte)........................................................................... 24
2-6 相對電極 (counter electrode).......................................................... 26
2-7 電泳沉積 (electrophoretic deposition)............................................ 27
2-7.1 電泳沉積原理........................................................................... 27
2-7.2 懸浮液種類............................................................................... 28
2-7.3 粒子電荷來源........................................................................... 29
2-7.4 膠體粒子分散........................................................................... 29
2-7.5 電泳沉積於染料敏化太陽能電池之應用............................... 31
2-8 可撓式基板於染料敏化太陽能電池之發展現況........................... 32
第三章 實驗方法與儀器原理介紹………................................. 34
3-1 實驗藥品........................................................................................... 34
3-2 實驗儀器設備................................................................................... 36
3-3 二氧化鈦奈米顆粒電泳液的製備與相關測試............................... 37
3-3.1 水熱法合成二氧化鈦奈米顆粒............................................... 37
3-3.2製備二氧化鈦奈米顆粒電泳液................................................. 37
3-3.3 XRD繞射分析............................................................................ 40
3-3.4 掃描式電子顯微鏡 (scanning electron microscope, SEM) 42
3-4組裝染料敏化太陽能電池................................................................ 43
3-4.1 Ti基板表面處理........................................................................ 43
3-4.2 Electrophoretic Deposition法製備TiO2薄膜電極.................... 43
3-4.3 染料敏化劑的吸附................................................................... 44

3-4.4 電解質的配置........................................................................... 44
3-4.5 相對電極的製備....................................................................... 45
3-4.6 組裝染料敏化太陽能電池....................................................... 45
3-5 電池的電性測試............................................................................... 46
3-5.1 I-V特性曲線的測試.................................................................. 46
3-5.2 IMPS與IMVS的測量................................................................ 48
3-5.3 Electrochemical Impedance Spectroscopy (EIS)........................ 51
第四章 結果與討論..................................................................... 53
4-1 相對電極上不同的白金厚度對染料敏化太陽能電池的影響....... 53
4-1.1 前言........................................................................................... 53
4-1.2 紫外光-可見光吸收光譜分析.................................................. 53
4-1.3 電池效率表現........................................................................... 54
4-1.4 交流阻抗頻譜(EIS)分析........................................................... 57
4-2 不同的燒結溫度對染料敏化太陽能電池的影響........................... 60
4-2.1 前言........................................................................................... 60
4-2.2 電池效率表現........................................................................... 61
4-3 電解質中不同I2濃度對染料敏化太陽能電池的影響.................... 63
4-3.1 前言........................................................................................... 63
4-3.2 紫外光-可見光吸收光譜分析.................................................. 64
4-3.3 電池效率表現........................................................................... 65
4-3.4 交流阻抗頻譜(EIS)分析........................................................... 67
4-4 不同厚度的二氧化鈦層對染料敏化太陽能電池的影響............... 70

4-4.1 前言........................................................................................... 70
4-4.2 電池效率表現........................................................................... 71
4-4.3 IMPS ＆IMVS分析..................................................................... 73
4-4.4 交流阻抗頻譜(EIS)分析........................................................... 79
4-5 加入不同成分的散射層對染料敏化太陽能電池的影響............... 86
4-5.1 前言........................................................................................... 86
4-5.2 XRD 分析.................................................................................. 89
4-5.3 TiO2層成膜後SEM分析........................................................... 90
4-5.4 紫外光-可見光吸收光譜分析.................................................. 92
4-5.5 電池效率表現........................................................................... 93
4-5.6 IMPS＆IMVS 分析.................................................................... 94
4-5.7 交流阻抗頻譜(EIS)分析........................................................... 99
第五章 結論與建議..................................................................... 102
第六章 參考文獻......................................................................... 104

[1]張菀倫,“太陽光電產業先趨前瞻佈局占得有利先機 茂迪迎向太陽光電產業大未來, 永續產業發展雙月刊, 2007, 29, 39.
[2]M.Grätzel, “Photoelectrochemical cells, Nature, 2001, 414, 338.
[3]莊家深, “太陽能工程-太陽電池篇, 全華, 1998, 第一章、第二章.
[4]S. R. Wenham, M. A. Green, Silicon Solar Cells, “Progress in Photovoltaics:Research and Applications, vol 4, p3-33 (1996)
[5]B. O’Regan, M.Grätzel, “A low-coat, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films, Nature, 1991, 353, 737.
[6]Y. Chiba, A. Islam, Y. Watanabe, R. Komiya, N. Koide, L. Han, “Dye-Sensitized Solar Cells with Conversion Efficiency of 11.1%, Jpn. J. Appl. Phys., 2006, 45, 25, L638.
[7]C. Y. Chen, M. K. Wang, J. Y. Li , N. Pootrakulchote, L. Alibabaei, C. H. Ngoc-le, J. D. Decoppet, J. H. Tsai, C. Gratzel, C. G. Wu, S. M. Zakeeruddin, M. Gratzel, “Highly Efficient Light-Harvesting Ruthenium Sensitizer for Thin-Film Dye-Sensitized Solar Cells, ACS nano, 2009, 3, 3103.
[8]F.F. Reuss, Mém. Soc. Impériale Naturalistes de Moscow 2, 1809, p. 327.
[9]Zhitomirsky, “Cathodic electrodeposition of ceramic and organoceramic materials. Fundamental aspects, Adv. Colloid Interface Sci., 2002, 97, 279.
[10]D. Cahen, G. Hodes, M. Grätzel, J. F. Guillemoles, I. Riess, “Nature of Photovoltaic Action in Dye-Sensitized Solar Cells, J. Phys. Chem. B, 2000, 104, 2053.
[11]D. Matthews, P. Infelta, M. Grätzel, “Calculation of the photocurrent-potential characteristic for regenerative, sensitized semiconductor electrodes, Sol. Energy Mater. Sol. Cells, 1996, 44, 119.
[12]M. Grätzel, “Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells, J. Photochem. Photobio. A, 2004, 164, 3.
[13]A. Hagfeldt, M. Grätzel, “Light-Induced Redox Reactions in Nanocrystalline Systems, Chem. Rev., 1995, 95, 49.
[14]C. J. Barbé, F. Arendse, P. Comte, M. Jirousek, F. Lenzmann, V. Shklover, M. Grätzel, “Nanocrystalline Titanium Oxide Electrodes for Photovoltaic Applications, J. Am. Ceram. Soc., 1997, 80, 3157.
[15]K. Kalyanasundaram, M. Grätzel, “Applications of functionalized transition metal complex in photonic and optoelectronic devices, Coord. Chem. rev., 1998, 177, 34.
[16]N.-G. Park, J. van de Lagemaat, A. J. Frank, “Comparison of Dye-Sensitized Rutile- and Anatase-Based TiO2 Solar Cells, J. Phys. Chem. B, 2000, 104, 8989.
[17]M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Müller, P. Liska, N. Vlachopoulos, M. Grätzel, “Conversion of Light to Electricity by cis-X2Bis (2,2’-bipyridyl-4,4’-dicarboxylate)ruthenium(II) Charge- Transfer Sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on Nanocrystalline TiO2 Electrodes, J. Am. Chem. Soc., 1993, 115, 6382.
[18]G. P. Smestad, M. Grätzel, “Demonstrating Electron Transfer and Nanotechnology: A Natural Dye-Sensitized Nanocrystalline Energy Converter, J. Chem. Educ., 1998, 75, 752.
[19]M. K. Nazeeruddin, P. Péchy, T. Renouard, S. M. Zakeerudin, R. Humphry-Baker, P. Comte, P. Liska, L. Cevey, E. Costa, V. Shklover, L. Spiccia, G. B. Deacon, C. A. Bignozzi, M. Grätzel, “Engineering of efficient panchromatic sensitizers for nanocrystalline TiO2-based solar cells, J. Am. Chem. Soc., 2001, 123, 1613.
[20]M. K. Nazeeruddin, F. D. Angelis, S. Fantacci, A. Selloni, G. Viscardi, P. Liska, S. Ito, B. Takeru, M. Grätzel, “Combined experimental and DFT-TDDFT computational study of photoelectrochemical cell ruthenium sensitizers, J. Am. Chem. Soc., 2005, 127, 16835.
[21]M. K. Nazeeruddin, R. Humphry-Baker, P. Liska, M. Grätzel, “Investigation of Sensitizer Adsorption and the Influence of Protons on Current and Voltage of a Dye-Sensitized Nanocrystalline TiO2 Solar Cell, J. Phys. Chem. B, 2003, 107, 8981.
[22]G. J. Meyer, “Efficient Light to Electrical Energy Conversion: Nanocrystalline TiO2 Films Modified with Inorganic Sensitizers, J. Chem. Educ., 1997, 74, 652.
[23]S. Cherian, C. C. Wamser, “Adsorption and photoactivity of tetra(4-carboxyphenyl)porphyrin (TCPP) on nanoparticulate TiO2, J. Phys. Chem. B, 2000, 104, 3624.
[24]http://www.solaronix.com/
[25]S. Y. Huang, G. Schlichthorl, A.J. Nozik, “Charge Recombination in Dye-Sensitized Nanocrystalline TiO2 Solar Cell, J. Phys. Chem. B, 1997, 101, 2576.
[26]A. Hauch, R. Kern, J. Ferber, 2nd World Conference, Vienna, European Communities, 1998.
[27]N. Papageorgiou, M. Grätzel, P. P. Infelta, “On the Relevance of Mass Transport in Thin Layer Nanocrystalline Photoelectrochemical Solar Cells, Sol. Energy Mater. Sol. Cells, 1996, 44(4), 405.
[28]U. Bach, D. Lupo, P. Comte, “Solid-State Dye Sensitized Mesoporous TiO2 Solar Cells with High Photo-to-electron Conversion Efficiencies, Nature, 1998, 395, 583.
[29]P. Wang, S. M. Zakeeruddin, I. Exnarb, M. Grätzel, “High Efficiency Dye-Sensitized Nanocrystalline Solar Cells Based on Ionic Liquid Polymer Gel Electrolyte, Chem. Commun., 2002, 2972.
[30]E. Stathatos, P. Lianos, “A Quasi-Solid-State Dye-Sensitized Solar Cell Based on a Sol-Gel Nanocomposite Electrolyte Containing Ionic Liquid, Chem. Mater., 2003, 15, 1825.
[31]N. Papageorgiou, W. F. Maier, M. Grätzel, “An Iodine/Triiodide Reduction Electrocatalyst for Aqueous and Organic Media, J. Electrochem. Soc., 1996, 144, 99.
[32]A. Kay, M. Grätzel, “Low cost photovoltaic modules based on dye sensitized nanocrystalline titanium dioxide and carbon powder, Sol. Energy Mater. Sol. Cells, 1996, 44, 99.
[33]K. Kamada, K. Maehara, M. Mukai, S. Ida, Y. Matsumoto, “Fabrication of metal oxide-diamond composite films by electrophoretic deposition and anodic dissolution, J. Mater. Res. 2003, 18, 2826.
[34]A. Formento, L. Montanaro, and M. V. Swain, “Micromechanical Characterization of Electrophoretic-Deposited Green Films, J. Am. Ceram. Soc., 1999, 82, 3521.
[35]O. O. Van der Biest, and L. J. Vandeperre, “Electrophoretic Deposition of Materials, Annu. Rev. Mater. Sci., 1999, 29, 327.
[36]J. A. Lewis, “Colloidal Processing of Ceramics, J. Am. Ceram. Soc., 2000, 83, 2341.
[37]D. Matthews, A. Kay, M. Grätzel, “Electrophoretically Deposited Titanium-Dioxide Thin-Films for Photovoltaic Cells, Aust. J. Chem., 1994, 47, 1869.
[38]K. Fujimura, S. Yoshikado, “Preparation of TiO2 Thin Film for Dye Sensitized Solar Cell Deposited by Electrophoresis Method, Key Eng. Mater., 2003, 248, 133.
[39]I. Zhitomirsky, “Cathodic electrodeposition of ceramic and organoceramic materials. Fundamental aspects, Adv. Colloid Interface Sci., 2002, 97, 279.
[40]J. Tabellion, R. Clasen, “Electrophoretic deposition from aqueous suspensions for near-shape manufacturing of advanced ceramics and glasses—applications, J. Mater. Sci., 2004, 39, 803.
[41]T. Miyasaka, Y. Kijitori, T. N. Murakami, M. Kimura, S. Uegusa, “Efficient Nonsintering Type Dye-sensitized Photocells Based on Electrophoretically Deposited TiO2 layers, Chem. Lett., 2002, 1250.
[42]T. N. Murakami, Y. Kijitori, N. Kawashima, T. Miyasaka, “UV Light-assisted Chemical Vapor Deposition of TiO2 for Efficiency Development at Dye-sensitized Mesoporous Layers on Plastic Film Electrodes, Chem. Lett., 2003, 32, 1076.
[43]L. Grinis, S. Dor, A. Ofir, A. Zaban, “Electrophoretic deposition and compression of titania nanoparticle films for dye-sensitized solar cells, J. Photochem. Photobiol. A, 2008, 198, 52.
[44]T. Miyasaka, Y. Kijitori, “Low-Temperature Fabrication of Dye-Sensitized Plastic Electrodes by Electrophoretic Preparation of Mesoporous TiO2 Layers, J. Electrochem. Soc., 2004, 151(11), A1767.
[45]C. Y. Jiang, X. W. Sun, K. W. Tan, G. Q. Lo, A. K. K. Kyaw, D. L. Kwong, “High-bendability flexible dye-sensitized solar cell with a nanoparticle-modified ZnO-nanowire electrode, Appl. Phys. Lett., 2008, 92, 143101.
[46]S. Nakade, M. Matsuda, S. Kambe, Y. Saito, T. Kitamura, T. Sakata,
Y. Wada, H. Mori and S. Yanagida, “Dependence of TiO2 Nanoparticle Preparation Methods and Annealing Temperature on the Efficiency of Dye-Sensitized Solar Cells, J. Phys. Chem. B, 2002, 106, 10004.
[47]K. Onoda, S. Ngamsinlapasathian, T. Fujieda and S. Yoshikawa, “The superiority of Ti plate as the substrate of dye-sensitized solar cells, Sol. Energy Mater. Sol. Cells, 2007, 91, 1176.
[48]M. G. Kang, N. G. Park, K. S. Ryu, S. H. Chang, K. J. Kim, “Flexible Metallic Substrates for TiO2 Film of Dye-sensitized Solar Cells, Chem. Lett., 2005, 34, 804-805.
[49]X. Fang, T. Ma, G. Guan, M. Akiyama, T. Kida, E. Abe, “Effect of the thickness of the Pt film coated on a counter electrode on the performance of a dye-sensitized solar cell, J. Electroana. Chem., 2004, 570, 257–263.
[50]L. Y. Lin, C. P. Lee, R. Vittal, K. C. Ho, “Selective conditions for the fabrication of a flexible dye-sensitized solar cell with Ti/TiO2 photoanode, J. Power Sources, 2010, 195, 4344–4349.
[51]L. Y. Lin, P. C. Nien, C. P. Lee, K. W. Tsai, M. H. Yeh, R. Vittal, K. C. Ho, “Low-Temperature Flexible Photoanode and Net-Like Pt Counter Electrode for Improving the Performance of Dye-Sensitized Solar Cells, J. Phys. Chem. C 2010, 114, 21808–21815.
[52]C. H. Lee, W. H. Chiu, K. M. Lee, W. F. Hsieh, J. M. Wu, “Improved performance of flexible dye-sensitized solar cells by introducing an interfacial layer on Ti substrates, J. Mater. Chem., 2011, 21, 5114–5119.
[53]S. Ito, N. L. C. Ha, G. Rothenberger, P. Liska, P. Comte, S. M. Zakeeruddin, P. Pe´chy, M. K. Nazeeruddin,M.Gra¨tzel , “High-efficiency (7.2%) flexible dye-sensitized solar cells with Ti-metal substrate for nanocrystalline-TiO2 photoanode, Chem. Commun., 2006, 4004–4006.
[54]T. Kasuga, M. Hiramatsu, A. Hoson, T. Sekino, K. Niihara, “Formation of Titanium Oxide Nanotube, Langmuir, 1998, 14, 3160.
[55]T. Kasuga, M. Hiramatsu, A. Hoson, T. Sekino, K. Niihara, “Titania Nanotubes Prepared by Chemical Processing, Adv. Mater., 1999, 11, 1307.
[56]B. D. Cullity, S. R. Stock, “Elements of X-Ray Diffraction, 3rd ed., Prentice, 2001.
[57]C. Kittel, “Introduction to Solid State Physics, Wiley, 4th ed., 1971.
[58]M. Yan, F. Chen, J. Zhang, M. Anpo, “Preparation of Controllable Crystalline Titania and Study on the Photocatalytic Properties, J. Phys. Chem. B, 2005, 109, 8673.
[59]J. Krulger, R. Plass, M. Grätzel, P. J. Cameron, L. M. Peter, “Charge Transport and Back Reaction in Solid-State Dye-Sensitized Solar Cells: A Study Using Intensity-Modulated Photovoltage and Photocurrent Spectroscopy, J. Phys. Chem. B, 2003, 107, 7536.
[60]R. Kern, R. Sastrawan, J. Ferber, R. Stangl, J. Luther, “Modeling and interpretation of electrical impedance spectra of dye solar cells operated under open-circuit conditions, Electrochim. Atca, 2002, 47, 4213.
[61]F. Febregat-Santiago, J. Bisquert, E. Palomares, L. Otero, D. Kuang, S. M. Zakeeruddin, M. Grätzel, “Correlation between Photovoltaic Performance and Impedance Spectroscopy of Dye-Sensitized Solar Cells Based on Ionic Liquids, J. Phys. Chem. C, 2007, 111, 6550.
[62]M. Adachi, M. Sakamoto, J. Jiu, Y. Ogata, S. Isoda, “Determination of parameters of electron transport in dye-sensitized solar cells using electrochemical impedance spectroscopy, J. Phys. Chem. B, 2006, 110 , 13872.
[63]G. Kantonisa, T. Stergiopoulosa, A. P. Katsoulidisb, P. J. Pomonisb, P. Falarasa, Electron dynamics dependence on optimum dye loading for an efficient dye-sensitized solar cell, J. Photochem. Photobiol., A: Chemistry, 2011, 217, 236–241.
[64]S. Nakade, M. Matsuda, S. Kambe, Y. Saito, T. Kitamura, T. Sakata, Y. Wada, H. Mori, S. Yanagida, “Dependence of TiO2 Nanoparticle Preparation Methods and Annealing Temperature on the Efficiency of Dye-Sensitized Solar Cells, J. Phys. Chem. B, 2002, 106, 10004-10010.
[65]A. I. Popov, R. F. Swensen, J. Am. Chem. Soc., 1955, 77, 3724–3726.

[66]S. Ito, P. Liska, P. Comte, R. Charvet, P. Pe´chy, U. Bach, L. Schmidt-Mende, S. M. Zakeeruddin, A. Kay, M. K. Nazeeruddin, M, Gra¨tzel, “Control of dark current in photoelectrochemical (TiO2/ I--I3-) and dye-sensitized solar cell, Chem. Comm., 2005, 4351.
[67]劉永進, “染料敏化太陽能電池剛性及可繞式二氧化鈦層之電泳成膜研究, 國立成功大學化學工程研究所碩士論文, 2011.
[68]Y. J. Liou, P. T. Hsiao, L. C. Chen, Y. Y. Chu, H. S. Teng, “Structure and Electron-Conducting Ability of TiO2 Films from Electrophoretic Deposition and Paste-Coating for Dye-Sensitized Solar Cells, J. Phys. Chem. C, 2011, 115, 25580–25589.
[69]P. T. Hsiao, Y. J. Liou, H. S. Teng, “Electron Transport Patterns in TiO2 Nanotube Arrays Based Dye-Sensitized Solar Cells under Frontside and Backside Illuminations, J. Phys. Chem. C, 2011, 115, 15018–15024.
[70]P. T. Hsiao, Y. L. Tung, H. Teng, “Electron Transport Patterns in TiO2 Nanocrystalline Films of Dye-Sensitized Solar Cells, J. Phys. Chem. C, 2010, 114, 6762.
[71]N. Kopidakis, K. D. Benkstein, J. van de Lagemaat, A. J. Frank, “Transport-Limited Recombination of Photocarriers in Dye-Sensitized Nanocrystalline TiO2 Solar Cells, J. Phys. Chem. B, 2003, 107, 11307.
[72]L. M. Peter, “Characterization and modeling of dye-sensitized solar cells, J. Phys. Chem. C, 2007, 111, 6601.
[73]Y. Tachibana, K. Hara, K. Sayama, H. Arakawa, “Quantitative Analysis of Light-Harvesting Efficiency and Electron-Transfer Yield in Ruthenium-Dye-Sensitized Nanocrystalline TiO2 Solar Cells, Chem. Mater. 2002, 14, 2527-2535.
[74]G. Rothenberger, P. Comte, M. Gra¨tzel, “A contribution to the optical design of dye-sensitized nanocrystalline solar cells, Sol. Energy Mater. Sol. Cells, 1999, 58, 321–336.
[75]Y. Tachibana, K. Hara, K, Sayama, H, Arakawa, “Quantitative analysis of light-harvesting efficiency and electron-transferyield in ruthenium-dye-sensitized nanocrystalline TiO2 solar cells, Chem. Mater., 2002, 14, 2527–2535.
[76]S. Ito, S. Yoshida, T. Watanabe, “Preparation of Colloidal Anatase TiO2 Secondary Submicroparticles by Hydrothermal Sol-Gel Method, Chem. Lett., 2000, 29, 70–71.
[77]S. Ito, P. Chen, P. Comte, M. K. Nazeeruddin, P. Liska, P. Pe´chy, M. Gra¨tzel, “Fabrication of Screen-Printing Pastes From TiO2 Powders for Dye-Sensitised Solar Cells, 2007.