本研究使用溶膠凝膠法搭配微波溶熱法合成銳鈦礦相二氧化鈦，以異丙醇和辛醇作為反應溶劑，合成出發展晶面及晶粒大小不同的二氧化鈦，本製程不須經過粉末乾燥及研磨程序，即可直接將反應所得之二氧化鈦膠體溶液製成二氧化鈦漿料，並將其應用於染料敏化太陽能電池 (Dye-sensitized solar cells，DSSCs) 之工作電極，大幅簡化並縮短漿料製成程序與時間。以異丙醇合成之二氧化鈦(IPA)晶粒大小約為25 nm，且具有{001}及{010}晶面有助於電子的傳遞；利用辛醇所合成出的二氧化鈦(OCT)晶粒大小為5 nm，具有較高的比表面積。本研究嘗試將兩種不同顆粒大小的二氧化鈦晶粒混合，結合兩種二氧化鈦顆粒的優點，製備出混合型漿料IPA/OCT，探討IPA、OCT及IPA/OCT三種工作電極之染料吸附量，以及在不同光照度下的光伏特性和光電轉換效率之影響。研究結果顯示，適用於1 sun與室內光照環境下的DSSC，其對二氧化鈦光電極的要求完全不同。在強光照射下，染料吸附量為決定轉換效率的關鍵因素，而在弱光條件下，二氧化鈦電極的透明度以及電子復合機率則影響較為重大。本研究所製成之IPA/OCT混合型電極，可同時適用於兩種不同光照環境，在疊加散射層後，在1 sun與室內光200 lux的條件下光電轉換效率分別可達到9.92%與12.46%。

We reported sol-gel via micro-wave solvothermal process to synthesize nanocrystalline anatase TiO2. Through using different kinds of alcohol as solvent, anatase nanocrystallites were obtained with different major exposed facets and sizes. By using isopropanol (IPA) can synthesize TiO2 in size of 20-30 nm with dominant {001}/{010} facets; whereas the ultrafine crystalline size of 5 nm with dominant {101}-facet was derived by octanol (OCT). We attempted to make mixed IPA/OCT paste as heterogeneous TiO2 paste (IPA/OCT) to fabricate photoanode and expected to combine the advantages of IPA and OCT. The influence of different TiO2 on the photovoltaic performance for sunlight and indoor light were investigated. The results showed that the condition for 1 sun and indoor light were quite different. The crucial factor under 1 sun irradiation is dye loading ability; yet, the film transparency and electron recombination rate were the key points for room light condition. In this study, using mixed IPA/OCT as photoanode was observed that it was suitable for both 1 sun and indoor light irradiations. The IPA/OCT-based cells exhibited the highest PCE of 9.05% and 12.46% under sunlight and indoor light, respectively.

[1] B. O’regan and M. Gratzel, "A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films," nature, 353, 737-740, 1991.
[2] F. De Rossi, T. Pontecorvo, and T. M. Brown, "Characterization of photovoltaic devices for indoor light harvesting and customization of flexible dye solar cells to deliver superior efficiency under artificial lighting," Applied Energy, 156, 413-422, 2015.
[3] J.-L. Lan, T.-C. Wei, S.-P. Feng, C.-C. Wan, and G. Cao, "Effects of Iodine Content in the Electrolyte on the Charge Transfer and Power Conversion Efficiency of Dye-Sensitized Solar Cells under Low Light Intensities," The Journal of Physical Chemistry C, 116, 25727-25733, 2012.
[4] M. Baghbanzadeh, L. Carbone, P. D. Cozzoli, and C. O. Kappe, "Microwave‐assisted synthesis of colloidal inorganic nanocrystals," Angewandte Chemie International Edition, 50, 11312-11359, 2011.
[5] P. Chen, J.-D. Peng, C.-H. Liao, P.-S. Shen, and P.-L. Kuo, "Microwave-assisted hydrothermal synthesis of TiO2 spheres with efficient photovoltaic performance for dye-sensitized solar cells," Journal of nanoparticle research, 15, 1465, 2013.
[6] P.-S. Shen, Y.-C. Tai, P. Chen, and Y.-C. Wu, "Clean and time-effective synthesis of anatase TiO2 nanocrystalline by microwave-assisted solvothermal method for dye-sensitized solar cells," Journal of Power Sources, 247, 444-451, 2014.
[7] G. Li et al., "Synergistic effect between anatase and rutile TiO2 nanoparticles in dye-sensitized solar cells," Dalton Transactions, 45, 10078-10085, 2009.
[8] S. Kambe, S. Nakade, Y. Wada, T. Kitamura, and S. Yanagida, "Effects of crystal structure, size, shape and surface structural differences on photo-induced electron transport in TiO2 mesoporous electrodes," Journal of Materials Chemistry, 12, 723-728, 2002.
[9] N.-G. Park, J. Van de Lagemaat, and A. Frank, "Comparison of dye-sensitized rutile-and anatase-based TiO2 solar cells," The Journal of Physical Chemistry B, 104, 8989-8994, 2000.
[10] N.-G. Park, G. Schlichthörl, J. Van de Lagemaat, H. Cheong, A. Mascarenhas, and A. Frank, "Dye-sensitized TiO2 solar cells: structural and photoelectrochemical characterization of nanocrystalline electrodes formed from the hydrolysis of TiCl4," Journal of Physical Chemistry B, 103, 3308-3314, 1999.
[11] U. Diebold, "The surface science of titanium dioxide," Surface Science Reports, 48, 53-229, 2003.
[12] J. Livage, M. Henry, and C. Sanchez, "Sol-gel chemistry of transition metal oxides," Progress in Solid State Chemistry, 18, 259-341, 1988.
[13] 張天益, "利用溶膠-凝膠法製備鋯鈦酸鉛陶瓷塊材與薄膜之研究," 國立成功大學材料工程研究所碩士論文, 2007.
[14] V. K. LaMer and R. H. Dinegar, "Theory, production and mechanism of formation of monodispersed hydrosols," Journal of the American Chemical Society, 72, 4847-4854, 1950.
[15] T. Sugimoto, "Underlying mechanisms in size control of uniform nanoparticles," Journal of Colloid and Interface Science, 309, 106-118, 2007.
[16] T. Sugimoto, "Preparation of monodispersed colloidal particles," Advances in Colloid and Interface Science, 28, 65-108, 1987.
[17] H. Reiss, "The growth of uniform colloidal dispersions," Journal of Chemical Physics, 19, 482-487, 1951.
[18] M. Niederberger and H. Cölfen, "Oriented attachment and mesocrystals: non-classical crystallization mechanisms based on nanoparticle assembly," Physical Chemistry Chemical Physics, 8, 3271-3287, 2006.
[19] G. J. Wilson, A. S. Matijasevich, D. R. Mitchell, J. C. Schulz, and G. D. Will, "Modification of TiO2 for enhanced surface properties: finite Ostwald ripening by a microwave hydrothermal process," Langmuir, 22, 2016-2027, 2006.
[20] D. Fairhurst and R.-W. Lee, "Aggregation, Agglomeration-How to Avoid Aggravation When Formulating Particulate Suspensions," Drug Delivery Technology, 8 , 48-52, 2008.
[21] C. Ribeiro, C. M. Barrado, E. R. de Camargo, E. Longo, and E. R. Leite, "Phase transformation in titania nanocrystals by the oriented attachment mechanism: the role of the pH value," Chemistry–A European Journal, 15, 2217-2222, 2009.
[22] A. S. Barnard and P. Zapol, "Predicting the energetics, phase stability, and morphology evolution of faceted and spherical anatase nanocrystals," Journal of Physical Chemistry B, 108, 18435-18440, 2004.
[23] Y.-W. Jun, M.-F. Casula, J.-H. Sim, S.-Y. Kim, J. Cheon, and A.P. Alivisatos, "Surfactant-assisted elimination of a high energy facet as a means of controlling the shapes of TiO2 nanocrystals," Journal of the American Chemical Society, 125, 15981-15985, 2003.
[24] Y.-W. Jun, J.-S. Choi, and J. Cheon, "Shape control of semiconductor and metal oxide nanocrystals through nonhydrolytic colloidal routes," Angewandte Chemie International Edition, 45, 3414-3439, 2006.
[25] Y.-C. Wu and Y.-C. Tai, "Effects of alcohol solvents on anatase TiO2 nanocrystals prepared by microwave-assisted solvothermal method," Journal of Nanoparticle Research, 15, 1686-1696, 2013.
[26] C.-C. Wang and J.-Y. Ying, "Sol-gel synthesis and hydrothermal processing of anatase and rutile titania nanocrystals," Chemistry of Materials, 11, 3113-3120, 1999.
[27] C.-S. Kim, B.-K. Moon, J.-H. Park, B.-C. Choi, and H.-J. Seo, "Solvothermal synthesis of nanocrystalline TiO2 in toluene with surfactant," Journal of Crystal Growth, 257, 309-315, 2003.
[28] H.-G. Yang, C.-H. Sun, S.-Z. Qiao, J. Zou, G. Liu, S. C. Smith, H.-M.Cheng and G.-Q. Lu, "Anatase TiO2 single crystals with a large percentage of reactive facets," Nature, 453, 638-641, 2008.
[29] X.-H. Yang, H.-G. Yang, and C. Li, "Controllable nanocarving of anatase TiO2 single crystals with reactive {001} facets," Chemistry–A European Journal, 17, 6615-6619, 2011.
[30] X. Han, Q. Kuang, M. Jin, Z. Xie, and L. Zheng, "Synthesis of titania nanosheets with a high percentage of exposed (001) facets and related photocatalytic properties," Journal of the American Chemical Society, 131, 3152-3153, 2009.
[31] J.-S. Chen and X.-W. Lou, "Anatase TiO2 nanosheet: an ideal host structure for fast and efficient lithium insertion/extraction," Electrochemistry Communications, 11, 2332-2335, 2009.
[32] H.-G. Yang, G. Liu, S.-Z. Qiao, C.-H. Sun, Y.-G. Jin, S. C. Smith, J.Zou, H.-M. Cheng, and G.-Q. Lu, "Solvothermal synthesis and photoreactivity of anatase TiO2 nanosheets with dominant {001} facets," Journal of the American Chemical Society, 131, 4078-4083, 2009.
[33] 張育誠, "研究微波加熱技術在奈米材料之合成、自組裝及分解機構," 國立清華大學碩士論文, 2003.
[34] 蘇裕勝, "利用液相組合式合成法合成苯并米雜環分子庫," 國立東華大學碩士論文, 2003.
[35] 紀柏享, 楊末雄, 孫毓璋, "微波消化之方法應用," 中國化學會, 56, 269-284, 1998.
[36] M. Gratzel, "Photoelectrochemical cells," Nature, 414, 338-344, 2001.
[37] M. Gratzel, "Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells," Journal of Photochemistry and Photobiology A: Chemistry, 164, 3-14, 2004.
[38] 陳俐靜, "應用於染料敏化太陽能電池之二氧化鈦奈米粒、奈米棒及其混摻型薄膜電極的製備與鑑識", 國立交通大學碩士論文, 2009.
[39] H.-P. Wu, C.-M. Lan, J.-Y. Hu, W.-K. Huang, J.-W. Shiu,Z.-J. Lan, C.-M. Tsai, C.-H. Su and E. W.-G. Diau, "Hybrid titania photoanodes with a nanostructured multi-layer configuration for highly efficient dye-sensitized solar cells," Journal of Physical Chemistry letters, 4, 1570-1577, 2013.
[40] U. Sulaeman and A. Z. Abdullah, "The way forward for the modification of dye-sensitized solar cell towards better power conversion efficiency," Renewable and Sustainable Energy Reviews, 74, 438-452, 2017.
[41] A. Zaban, S. Ferrere, and B. A. Gregg, "Relative energetics at the semiconductor/sensitizing dye/electrolyte interface," Journal of Physical Chemistry B, 102, 452-460, 1998.
[42] J. Nissfolk, K. Fredin, A. Hagfeldt, and G. Boschloo, "Recombination and transport processes in dye-sensitized solar cells investigated under working conditions," Journal of Physical Chemistry B, 110, 17715-17718, 2006.
[43] M.-J. Jeng, Y.-L. Wung, L.-B. Chang, and L. Chow, "Particle size effects of TiO2 layers on the solar efficiency of dye-sensitized solar cells," International Journal of Photoenergy, 2013, 1-9, 2013.
[44] Y. Cui, L. Zhang, K. Lv, G. Zhou, and Z.-S. Wang, "Low temperature preparation of TiO2 nanoparticle chains without hydrothermal treatment for highly efficient dye-sensitized solar cells," Journal of Materials Chemistry A, 3, 4477-4483, 2015.
[45] A. Hegazy and E. Prouzet, "Room temperature synthesis and thermal evolution of porous nanocrystalline TiO2 anatase," Chemistry of Materials, 24, 245-254, 2012.
[46] A. Hegazy, N. Kinadjian, B. Sadeghimakki, S. Sivoththaman, N. K. Allam, and E. Prouzet, "TiO2 nanoparticles optimized for photoanodes tested in large area Dye-sensitized solar cells (DSSC)," Solar Energy Materials and Solar Cells, 153, 108-116, 2016.
[47] M. B. Qadir, K.-C. Sun, I. A. Sahito, A. A. Arbab, B. J. Choi, S.-C. Yi and S.-H. Jeong, "Composite multi-functional over layer: A novel design to improve the photovoltaic performance of DSSC," Solar Energy Materials and Solar Cells, 140, 141-149, 2015.
[48] U. T. Pawar, S. A. Pawar, J.-H. Kim, and P. S. Patil, "Dye sensitized solar cells based on hydrothermally grown TiO2 nanostars over nanorods," Ceramics International, 42, 8038-8043, 2016.
[49] K. Pugazhendhi, W. Jeyarani, T. Tenkyong, P. N. Kumar, B. Praveen, and J. Shyla, "Highly Porous and Novel 1D-TiO2 Nanoarchitecture with Light Harvesting Morphology for Photovoltaic Applications," Mechanics, Materials Science & Engineering Journal, 9,2412-2420, 2017.
[50] J. Yu, J. Low, W. Xiao, P. Zhou, and M. Jaroniec, "Enhanced photocatalytic CO2-reduction activity of anatase TiO2 by coexposed {001} and {101} facets," Journal of the American Chemical Society, 136, 8839-8842, 2014.
[51] B. Laskova, T. Moehl, L. Kavan, M. Zukalova, X. Liu, A. Yella, P. Comte, A. Zukal, M. K. Nazeeruddin and M. Graetzel, "Electron Kinetics in Dye Sensitized Solar Cells Employing Anatase with (101) and (001) Facets," Electrochimica Acta, 160, 296-305, 2015.
[52] L. Chu, Z. Qin, J. Yang, and X. Li, "Anatase TiO2 Nanoparticles with Exposed {001} Facets for Efficient Dye-Sensitized Solar Cells," Scientific Reports, 5, 12143, 2015.
[53] J.-D. Peng, C.-M. Tseng, R. Vittal, and K.-C. Ho, "Mesoporous anatase-TiO2 spheres consisting of nanosheets of exposed (001)-facets for [Co(byp)3]2+/3+ based dye-sensitized solar cells," Nano Energy, 22, 136-148, 2016.
[54] X.-Q. Gong and A. Selloni, "Reactivity of anatase TiO2 nanoparticles: the role of the minority (001) surface," Journal of Physical Chemistry B, 109, 19560-19562, 2005.
[55] P. Wen, H. Itoh, W. Tang, and Q. Feng, "Single nanocrystals of anatase-type TiO2 prepared from layered titanate nanosheets: Formation mechanism and characterization of surface properties," Langmuir, 23, 11782-11790, 2007.
[56] P. Wen, Y. Ishikawa, H. Itoh, and Q. Feng, "Topotactic transformation reaction from layered titanate nanosheets into anatase nanocrystals," Journal of Physical Chemistry C, 113, 20275-20280, 2009.
[57] C. Chen, L. Xu, G. A. Sewvandi, T. Kusunose, Y. Tanaka, S. Nakanishi and Q. Feng, "Microwave-Assisted Topochemical Conversion of Layered Titanate Nanosheets to {010}-Faceted Anatase Nanocrystals for High Performance Photocatalysts and Dye-Sensitized Solar Cells," Crystal Growth & Design, 14, 5801-5811, 2014.
[58] P. Wang, J. Lei, M. Xing, L. Wang, Y. Liu, and J. Zhang, "Ammonium acetate and ethylenediamine-assisted synthesis of anatase nanocrystals with {010} facets and enhanced photocatalytic activity," Journal of Environmental Chemical Engineering, 3, 961-968, 2015.
[59] T. Tachikawa and T. Majima, "Photocatalytic oxidation surfaces on anatase TiO2 crystals revealed by single-particle chemiluminescence imaging," Chemical Communications, 48, 3300-3302, 2012.
[60] C. J. Barbe´, F. Arendse, M. Jirousek, F. Lenzmann,V. Shklover and M. Gratzel, "Nanocrystalline Titanium Oxide Electrodes for Photovoltaic Applications," Journal of the American Ceramic Society, 80, 3157-71, 1997.
[61] J. Ferber and J. Luther, "Computer simulations of light scattering and absorption in dye-sensitized solar cells," Solar Energy Materials and Solar Cells, 54, 265-275, 1998.
[62] C.-M. Lan, S.-E. Liu, J.-W. Shiu, J.-Y. Hu, M.-H. Lin, and E. W.-G. Diau, "Formation of size-tunable dandelion-like hierarchical rutile titania nanospheres for dye-sensitized solar cells," RSC Advances, 3, 559-565, 2013.
[63] X. Sun, X. Zhou, Y. Xu, P. Sun, N. Huang, and Y. Sun, "Mixed P25 nanoparticles and large rutile particles as a top scattering layer to enhance performance of nanocrystalline TiO2 based dye-sensitized solar cells," Applied Surface Science, 337, 188-194, 2015.
[64] W.-T. Wu, S.-H. Yang, C.-M. Hsu, and W.-T. Wu, "Study of graphene nanoflake as counter electrode in dye sensitized solar cells," Diamond and Related Materials, 65, 91-95, 2016.
[65] M. Janani, P. Srikrishnarka, S. V. Nair, and A. S. Nair, "An in-depth review on the role of carbon nanostructures in dye-sensitized solar cells," Journal of Materials Chemistry A, 3, 17914-17938, 2015.
[66] X. Cui, W. Xu, Z. Xie, and Y. Wang, "High-performance dye-sensitized solar cells based on Ag-doped SnS2 counter electrodes," Journal of Materials Chemistry A, 4, 1908-1914, 2016.
[67] M. Nazeruddin, A. Kay, I. Rodicio, R. .H. Baker, E. Mueller, P. Liska, N. Vlachopoulos and M. Graetzel, "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 titanium dioxide electrodes," Journal of the American Chemical Society, 115, 6382-6390, 1993.
[68] K. Kalyanasundaram and M. Graetzel, "Efficient dye-sensitized solar cells for direct conversion of sunlight to electricity," Material Matters, 4, 88-90, 2009.
[69] R.-X. Dong, S.-Y. Shen, H.-W. Chen, C.-C. Wang, P.-T. Shih, C.-T. Liu, R. Vittal, J.-J. Lin and K.-C. Ho, "A novel polymer gel electrolyte for highly efficient dye-sensitized solar cells," Journal of Materials Chemistry A, 1, 8471-8478, 2013.
[70] C. Wu, L. Jia, S. Guo, S. Han, B. Chi, J. Pu and L. Jian, "Open-Circuit Voltage Enhancement on the Basis of Polymer Gel Electrolyte for a Highly Stable Dye-Sensitized Solar Cell," ACS Applied Materials and Interfaces, 5, 7886-7892, 2013.
[71] I.-P. Liu, W.-N. Hung, H. Teng, V. Shanmugam, J.-C. Lin, and Y.-L. Lee, "High-performance printable electrolytes for dye-sensitized solar cells," Journal of Materials Chemistry A, 2017.
[72] S. Ito, P. Chen, P. Comte, M. K. Nazeeruddin, P. Liska, P. Pechy and M. Graetzel, "Fabrication of screen-printing pastes from TiO2 powders for dye-sensitised solar cells," Progress in Photovoltaics: Research and Applications, 15, 603-612, 2007.
[73] P. J. Cameron and L. M. Peter, "Characterization of Titanium Dioxide Blocking Layers in Dye-Sensitized Nanocrystalline Solar Cells," The Journal of Physical Chemistry B, 107, 14394-14400, 2003.
[74] C.-H. Lee, W.-H. Chiu, K.-M. Lee, W.-F. Hsieh, and J.-M. Wu, "Improved performance of flexible dye-sensitized solar cells by introducing an interfacial layer on Ti substrates," Journal of Materials Chemistry, 21, 5114, 2011.
[75] J. Li, W. Wu, J. Yang, J. Tang, Y. Long, and J. Hua, "Effect of chenodeoxycholic acid (CDCA) additive on phenothiazine dyes sensitized photovoltaic performance," Science China Chemistry, 54, 699-706, 2011.
[76] J. Yang, F. Guo, J. Hua, X. Li, W. Wu, Y. Qu and H. Tian, "Efficient and stable organic DSSC sensitizers bearing quinacridone and furan moieties as a planar π-spacer," Journal of Materials Chemistry, 22, 24356-24365, 2012.
[77] Electronics Tutorials - PN Junction Diode : Junction Diode Ideal and Real Characteristic , 2016.
[78] 陳恭世, "奈米顆粒敏化奈米晶體二氧化鈦之光電效應研究," 國立台灣大學碩士論文, 2005.
[79] K. K. N. Simon M. Sze, Physics of Semiconductor Devices. Hoboken, 2007.
[80] 陳韋先, "暫態光電壓/光電流量測技術應用於染料敏化太陽能電池之研究," 國立成功大學碩士論文, 2015.
[81] P. R. Barnes, K. Miettunen, X. Li, A. Y. Anderson, T. Bessho, M. Grätzel and B. C. O’Regan, "Interpretation of optoelectronic transient and charge extraction measurements in dye-sensitized solar cells," Advanced materials, 25, 1881-922, 2013.
[82] Q. Wang, J.-E. Moser, and M. Grätzel, "Electrochemical impedance spectroscopic analysis of dye-sensitized solar cells," The Journal of Physical Chemistry B, 109, 14945-14953, 2005.
[83] J. Bisquert, "Influence of the boundaries in the impedance of porous film electrodes," Physical Chemistry Chemical Physics, 2, 4185-4192, 2000.
[84] F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo, and A. Hagfeldt, "Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy," Solar Energy Materials and Solar Cells, 87, 117-131, 2005.
[85] J. Bisquert, "Theory of the impedance of electron diffusion and recombination in a thin layer," The Journal of Physical Chemistry B, 106, 325-333, 2002.
[86] K. Kalyanasundaram, Dye-sensitized Solar Cells: EPFL Press 2010.
[87] 張育銘, "使用交流阻抗法中傳輸線模組分析氧化鈮阻隔層對染料敏化太陽電池陽極界面逆電流抑制之研究," 國立清華大學碩士論文, 2014.
[88] W. Zhao, H. Bala, J. Chen, Y. Zhao, G. Sun, J. Cao and Z. Zhang, "Thickness-dependent electron transport performance of mesoporous TiO2 thin film for dye-sensitized solar cells," Electrochimica Acta, 114, 318-324, 2013.
[89] 洪肇崑, "以微波溶熱法合成超小奈米顆粒之二氧化鈦於染料敏化太陽能電池之應用," 國立成功大學碩士論文, 2016.
[90] Y.-F. Chan, C.-C. Wang, B.-H. Chen, and C.-Y. Chen, "Dye‐sensitized TiO2 solar cells based on nanocomposite photoanode containing plasma‐modified multi‐walled carbon nanotubes," Progress in Photovoltaics: Research and Applications, 21, 47-57, 2013.