本研究探討電解質經氧化物奈米粒子添加或處理後之電化學特性的改變，以及此電解質在染料敏化太陽能電池上的應用。首先，以二氧化鈦(TiO2)與氧化鋅(ZnO)兩種奈米粒子作為印刷式電解質之添加劑。實驗結果顯示，電解質加入TiO2奈米粒子之後，能降低元件中白金對電極與電解質界面間的電荷傳輸阻力(RPt)，亦可降低光電極薄膜之傳導帶能階，藉此兩效應提升元件之光電流；此外，TiO2奈米粒子的存在亦會抑制光電極與電解質間的電荷再結合，提高元件的開路電壓。藉由TiO2奈米粒子的添加，染敏電池於標準太陽光下的光電轉換效率可由8.40%提升至9.01%。另外，ZnO奈米粒子的添加則會顯著提升光電極傳導帶能階，此效應可提高元件之開路電壓，但電荷注入光電極之驅動力亦隨之下降，同時ZnO的存在也會降低電解質的離子導電度並提升RPt值，因此相對應之電池皆呈現較低的光電流及轉換效率。
雖然TiO2奈米粒子作為電解質添加劑時能有效提升電池效率，但TiO2粒子的存在易導致元件上染料脫附的現象，降低元件的穩定性。因此，在後續的探討中，TiO2奈米粒子僅作為處理劑，加至一般液態電解質中後，再藉由離心方式得到固液兩相，取液相部份作為染敏電池之電解質。實驗結果發現，由於電解質中TiO2奈米粒子表面呈現負電位，可吸附電解質中帶正電之離子，因此離心後的電解質中具有較少之正電離子，可促進I-/I3-氧化還原對在電解質中之傳輸，提升電解質與電極界面間的電荷轉移，同時降低電子與離子進行再結合之機率。液態電解質經TiO2奈米粒子處理後，其染敏電池效率可由8.35%提升至8.77%，進一步以聚乙二醇(PEO)與聚甲基丙烯酸甲酯(PMMA)高分子共混物作為增稠劑製備出可印刷式電解質，所應用之染敏元件不僅可達到9.04%之轉換效率，在60°C環境下測定500小時後亦展現較佳的穩定性。

In this study, nanofillers are employed to be an additive and a treatment agent, expecting to enhance the electrochemical property of the electrolyte and charge transfer of the device. Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles are employed to be additives for the printable electrolyte in this study. In the results, TiO2 nanoparticles can increase the current density by decreasing the charge transfer resistance between the electrolyte and the counter electrode (Rpt) and also shifting the conduction band of TiO2 photoanode to more positive potential slightly. In addition, the presence of TiO2 nanoparticles can also inhibit the recombination of the electrons occurring at the photoanode and electrolyte, contributing to a higher voltage. Therefore, the efficiency can increase from 8.40% to 9.01% by introducing 10 wt.% TiO2 nanoparticles into the printable electrolyte. And for ZnO nanoparticles, the voltage and fill factor can increase sharply but decreasing the current density by shifting the conduction band of TiO2 photoanode to more negative potential significantly. Moreover, ZnO nanoparticles may increase the Rpt and lower the ionic conductivity of the electrolyte, causing the performance becoming worse. Although nanofillers can enhance the efficiency, some kinds of nanofillers may have interaction with components of the electrolyte and the dye, leading to poor stability. Therefore, in the subsequent discussion, TiO2 nanoparticles are used as a treatment agent for electrolyte by staying in the electrolyte and then removing through centrifugation process. TiO2 nanoparticles as a treatment agent can adsorb some cations by negative surface potential. Because of the removal of some kinds of cations, the diffusion of redox couple (I-/I3-) and charge transfer will be promoted and reach a higher performance. Therefore, the electrolyte treated by TiO2 nanoparticles can increase the efficiency from 8.35% to 8.77%. Besides the treated printable electrolyte not only can achieve the efficiency of 9.04% but also exhibit better stability after stability test at 60°C for 500 hours compared to the printable electrolyte containing TiO2 nanoparticles.

[1] H. Tsubomura, M. Matsumura, Y. Nomura, and T. Amamiya, "Dye Sensitized Zinc Oxide: Aqueous Electrolyte: Platinum Photocell," Nature, vol. 261, pp. 402-403 1976.
[2] B. O’Regan and M. Grätzel, "A Low-cost, High-efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films," Nature, vol. 353, pp. 737-739, 1991.
[3] A. Pandikumar, S.-P. Lim, S. Jayabal, N. M. Huang, H. N. Lim, and R. Ramaraj, "Titania@gold plasmonic nanoarchitectures: An ideal photoanode for dye-sensitized solar cells," Renewable and Sustainable Energy Reviews, vol. 60, pp. 408-420, 2016.
[4] M. Grätzel, "Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells," Journal of Photochemistry and Photobiology A: Chemistry, vol. 164, no. 1-3, pp. 3-14, 2004.
[5] M. Grätzel, "Solar energy conversion by dye-sensitized photovoltaic cells," Inorganic chemistry, vol. 44, pp. 6841-6851, 2005.
[6] A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo, and H. Pettersson, "Dye-Sensitized Solar Cells," Chemical Reviews, vol. 110, pp. 6595-6663, 2010.
[7] Y.-Y. Kuo and C.-H. Chien, "Sinter-free transferring of anodized TiO2 nanotube-array onto a flexible and transparent sheet for dye-sensitized solar cells," Electrochimica Acta, vol. 91, pp. 337-343, 2013.
[8] H. C. Weerasinghe, P. M. Sirimanne, G. V. Franks, G. P. Simon, and Y. B. Cheng, "Low temperature chemically sintered nano-crystalline TiO2 electrodes for flexible dye-sensitized solar cells," Journal of Photochemistry and Photobiology A: Chemistry, vol. 213, no. 1, pp. 30-36, 2010.
[9] S. Ito, N. C. Ha, G. Rothenberger., P. Liska, P. Comte, S. M. Zakeeruddin, P. Péchy, M. K. Nazeeruddin and M. Grätzel, "High-efficiency (7.2%) flexible dye-sensitized solar cells with Ti-metal substrate for nanocrystalline-TiO2 photoanode," Chem Commun (Camb), no. 38, pp. 4004-6, Oct 14 2006.
[10] M. Grätzel, "Photoelectrochemical Cells.," Nature, vol. 414, pp. 338-344, 2001.
[11] X. Feng, K. Shankar, O. K. Varghese, M. Paulose, T. J. Latempa, and C. A. Grimes, "Vertically Aligned Single Crystal TiO2 Nanowire Arrays Grown Directly on Transparent Conducting Oxide Coated Glass: Synthesis Details and Applications," Nano Letter, vol. 8, pp. 3781-3786, 2008.
[12] J. Jiu, S. Isoda, F. Wang, and M. Adachi, "Dye-Sensitized Solar Cells Based on a Single-Crystalline TiO2 Nanorod Film," The Journal of Physical Chemistry B, vol. 110, pp. 2087-2092, 2006.
[13] W. Shockley and H. J. Queisser, "Detailed Balance Limit of Efficiency of p‐n Junction Solar Cells," Journal of Applied Physics, vol. 32, pp. 510-519, 1961.
[14] A. Hagfeldt and M. Grätzel, "Molecular Photovoltaics," Accounts of Chemical Research, vol. 33, no. 5, pp. 269-277, 2000.
[15] M. K. Nazeeruddin et al., "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," Journal of the American Chemical Society, vol. 115, pp. 6382-6390, 1993.
[16] M. K. Nazeeruddin, P. Péchy, and M. Grätzel, "Efficient Panchromatic Sensitization of Nanocrystalline TiO2 Films by a Black Dye Based on a Trithiocyanato–Ruthenium Complex," Chemical Communications, vol. 18, pp. 1705-1706, 1997.
[17] M. K. Nazeeruddin et al., "Combined Experimental and DFT-TDDFT Computational Study of Photoelectrochemical Cell Ruthenium Sensitizers," Journal of American Chemical Society, vol. 127, pp. 16835-16847, 2005.
[18] P. Wang, C. Klein, R. Humphry-Baker, S. M. Zakeeruddin, and M. Grätzel, "A High Molar Extinction Coefficient Sensitizer for Stable Dye-Sensitized Solar Cells," Journal of American Chemical Society, vol. 127, pp. 808-809, 2004.
[19] C.-Y. Chen et al., "Highly efficient light-harvesting ruthenium sensitizer for thin-film dye-sensitized solar cells," ACS nano, vol. 3, no. 10, pp. 3103-3109, 2009.
[20] Q. Yu et al., "High-efficiency dye-sensitized solar cells: the influence of lithium ions on exciton dissociation, charge recombination, and surface states," ACS nano, vol. 4, no. 10, pp. 6032-6038, 2010.
[21] T. Bessho, S. M. Zakeeruddin, C. Y. Yeh, E. W. Diau, and M. Grätzel, "Highly efficient mesoscopic dye-sensitized solar cells based on donor-acceptor-substituted porphyrins," Angew Chem Int Ed Engl, vol. 49, no. 37, pp. 6646-9, Sep 3 2010.
[22] A. Yella et al., "Porphyrin-sensitized solar cells with cobalt (II/III)–based redox electrolyte exceed 12 percent efficiency," science, vol. 334, no. 6056, pp. 629-634, 2011.
[23] S. Mathew et al., "Dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers," Nat Chem, vol. 6, no. 3, pp. 242-7, Mar 2014.
[24] S. Ito et al., "High-Efficiency Organic-Dye-Sensitized Solar Cells Controlled by Nanocrystalline-TiO2 Electrode Thickness," Advanced Materials, vol. 18, no. 9, pp. 1202-1205, 2006.
[25] S. Ito et al., "High-conversion-efficiency organic dye-sensitized solar cells with a novel indoline dye," Chem Commun (Camb), no. 41, pp. 5194-6, Nov 7 2008.
[26] G. Zhang et al., "High efficiency and stable dye-sensitized solar cells with an organic chromophore featuring a binary pi-conjugated spacer," Chem Commun (Camb), no. 16, pp. 2198-200, Apr 28 2009.
[27] W. Zeng et al., "Efficient Dye-Sensitized Solar Cells with an Organic Photosensitizer Featuring Orderly Conjugated Ethylenedioxythiophene and Dithienosilole Blocks," Chemistry of Materials, vol. 22, no. 5, pp. 1915-1925, 2010.
[28] K. Kakiage, Y. Aoyama, T. Yano, K. Oya, J. Fujisawa, and M. Hanaya, "Highly-efficient dye-sensitized solar cells with collaborative sensitization by silyl-anchor and carboxy-anchor dyes," Chem Commun (Camb), vol. 51, no. 88, pp. 15894-7, Nov 14 2015.
[29] G. Wolfbauer, A. M. Bond, J. C. Eklund, and D. R. MacFarlane, "A channel flow cell system specifically designed to test the efficiency of redox shuttles in dye sensitized solar cells," Solar energy materials and solar cells, vol. 70, no. 1, pp. 85-101, 2001.
[30] S. Nakade, T. Kanzaki, W. Kubo, T. Kitamura, Y. Wada, and S. Yanagida, "Role of electrolytes on charge recombination in dye-sensitized TiO2 solar cell (1): the case of solar cells using the I-/I3-redox couple," The Journal of Physical Chemistry B, vol. 109, no. 8, pp. 3480-3487, 2005.
[31] R. Harikisun and H. Desilvestro, "Long-term stability of dye solar cells," Solar Energy, vol. 85, no. 6, pp. 1179-1188, 2011.
[32] P. Balraju, P. Suresh, M. Kumar, M. S. Roy, and G. D. Sharma, "Effect of counter electrode, thickness and sintering temperature of TiO2 electrode and TBP addition in electrolyte on photovoltaic performance of dye sensitized solar cell using pyronine G (PYR) dye," Journal of Photochemistry and Photobiology A: Chemistry, vol. 206, no. 1, pp. 53-63, 2009.
[33] T. Stergiopoulos, I. M. Arabatzis, G. Katsaros, and P. Falaras, "Binary polyethylene oxide/titania solid-state redox electrolyte for highly efficient nanocrystalline TiO2 photoelectrochemical cells," Nano letters, vol. 2, no. 11, pp. 1259-1261, 2002.
[34] H. Greijer Agrell, J. Lindgren, and A. Hagfeldt, "Coordinative interactions in a dye-sensitized solar cell," Journal of Photochemistry and Photobiology A: Chemistry, vol. 164, no. 1-3, pp. 23-27, 2004.
[35] T. W. Hamann, "The end of iodide? Cobalt complex redox shuttles in DSSCs," Dalton Transactions, vol. 41, no. 11, pp. 3111-3115, 2012.
[36] S. M. Feldt, G. Wang, G. Boschloo, and A. Hagfeldt, "Effects of driving forces for recombination and regeneration on the photovoltaic performance of dye-sensitized solar cells using cobalt polypyridine redox couples," The Journal of Physical Chemistry C, vol. 115, no. 43, pp. 21500-21507, 2011.
[37] Y.-L. Lee, C.-L. Chen, L.-W. Chong, C.-H. Chen, Y.-F. Liu, and C.-F. Chi, "A platinum counter electrode with high electrochemical activity and high transparency for dye-sensitized solar cells," Electrochemistry Communications, vol. 12, no. 11, pp. 1662-1665, 2010.
[38] L.-L. Li, C.-W. Chang, H.-H. Wu, J.-W. Shiu, P.-T. Wu, and E. Wei-Guang Diau, "Morphological control of platinum nanostructures for highly efficient dye-sensitized solar cells," Journal of Materials Chemistry, vol. 22, no. 13, p. 6267, 2012.
[39] E. Olsen, G. Hagen, and S. E. Lindquist, "Dissolution of platinum in methoxy propionitrile containing LiI/I2," Solar Energy Materials and Solar Cells, vol. 63, no. 3, pp. 267-273, 2000.
[40] T. N. Murakami et al., "Highly Efficient Dye-Sensitized Solar Cells Based on Carbon Black Counter Electrodes," Journal of The Electrochemical Society, vol. 153, no. 12, p. A2255, 2006.
[41] K.-C. Huang et al., "A high performance dye-sensitized solar cell with a novel nanocomposite film of PtNP/MWCNT on the counter electrode," Journal of Materials Chemistry, vol. 20, no. 20, p. 4067, 2010.
[42] L. Kavan, J. H. Yum, and M. Grätzel, "Optically transparent cathode for dye-sensitized solar cells based on graphene nanoplatelets," Acs Nano, vol. 5, no. 1, pp. 165-172, 2010.
[43] J. M. Pringle, V. Armel, and D. R. MacFarlane, "Electrodeposited PEDOT-on-plastic cathodes for dye-sensitized solar cells," Chem. Commun., vol. 46, no. 29, pp. 5367-5369, 2010.
[44] F. Cao, G. Oskam, and P. C. Searson, "A solid state, dye sensitized photoelectrochemical cell," The Journal of Physical Chemistry, vol. 99, no. 47, pp. 17071-17073, 1995.
[45] P. Wang, S. M. Zakeeruddin, I. Exnar, and M. Grätzel, "High efficiency dye-sensitized nanocrystalline solar cells based on ionic liquid polymer gel electrolyte," Chem. Commun., no. 24, pp. 2972-2973, 2002.
[46] P. Wang, S. M. Zakeeruddin, J. E. Moser, M. K. Nazeeruddin, T. Sekiguchi, and M. Gratzel, "A stable quasi-solid-state dye-sensitized solar cell with an amphiphilic ruthenium sensitizer and polymer gel electrolyte," Nat Mater, vol. 2, no. 6, pp. 402-7, Jun 2003.
[47] C.-L. Chen, H. Teng, and Y.-L. Lee, "Preparation of highly efficient gel-state dye-sensitized solar cells using polymer gel electrolytes based on poly(acrylonitrile-co-vinyl acetate)," J. Mater. Chem., vol. 21, no. 3, pp. 628-632, 2011.
[48] C. L. Chen, H. Teng, and Y. L. Lee, "In situ gelation of electrolytes for highly efficient gel-state dye-sensitized solar cells," Adv Mater, vol. 23, no. 36, pp. 4199-204, Sep 22 2011.
[49] C. L. Chen et al., "Highly efficient gel-state dye-sensitized solar cells prepared using poly(acrylonitrile-co-vinyl acetate) based polymer electrolytes," Phys Chem Chem Phys, vol. 15, no. 10, pp. 3640-5, Mar 14 2013.
[50] R.-X. Dong et al., "A novel polymer gel electrolyte for highly efficient dye-sensitized solar cells," Journal of Materials Chemistry A, vol. 1, no. 29, pp. 8471-8478, 2013.
[51] C. Wang, L. Wang, Y. Shi, H. Zhang, and T. Ma, "Printable electrolytes for highly efficient quasi-solid-state dye-sensitized solar cells," Electrochimica Acta, vol. 91, pp. 302-306, 2013.
[52] S.-J. Seo, H.-J. Cha, Y. S. Kang, and M.-S. Kang, "Printable ternary component polymer-gel electrolytes for long-term stable dye-sensitized solar cells," Electrochimica Acta, vol. 145, pp. 217-223, 2014.
[53] T.-C. Wei, H.-H. Chen, Y.-H. Chang, and S. P. Feng, "Hydrophobic Electrolyte Pastes for Highly Durable Dye-Sensitized Solar Cells," Journal of The Electrochemical Society, vol. 161, no. 4, pp. H214-H219, 2014.
[54] S. Venkatesan, S.-C. Su, W.-N. Hung, I.-P. Liu, H. Teng, and Y.-L. Lee, "Printable electrolytes based on polyacrylonitrile and gamma-butyrolactone for dye-sensitized solar cell application," Journal of Power Sources, vol. 298, pp. 385-390, 2015.
[55] I.-P. Liu, W.-N. Hung, H. Teng, S. Venkatesan, J.-C. Lin, and Y.-L. Lee, "High-performance printable electrolytes for dye-sensitized solar cells," Journal of Materials Chemistry A, vol. 5, no. 19, pp. 9190-9197, 2017.
[56] S. Venkatesan, I.-P. Liu, J.-C. Lin, M.-H. Tsai, H. Teng, and Y.-L. Lee, "Highly efficient quasi-solid-state dye-sensitized solar cells using polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA)-based printable electrolytes," Journal of Materials Chemistry A, vol. 6, no. 21, pp. 10085-10094, 2018.
[57] M.-S. Kang, K.-S. Ahn, and J.-W. Lee, "Quasi-solid-state dye-sensitized solar cells employing ternary component polymer-gel electrolytes," Journal of Power Sources, vol. 180, no. 2, pp. 896-901, 2008.
[58] X. Zhang, H. Yang, H.-M. Xiong, F.-Y. Li, and Y.-Y. Xia, "A quasi-solid-state dye-sensitized solar cell based on the stable polymer-grafted nanoparticle composite electrolyte," Journal of power sources, vol. 160, no. 2, pp. 1451-1455, 2006.
[59] S. Venkatesan and Y.-L. Lee, "Nanofillers in the electrolytes of dye-sensitized solar cells – A short review," Coordination Chemistry Reviews, vol. 353, pp. 58-112, 2017.
[60] Giammar, Daniel E., Carolyn J. Maus, and Liyun Xie. "Effects of particle size and crystalline phase on lead adsorption to titanium dioxide nanoparticles." Environmental Engineering Science 24.1 (2007): 85-95.
[61] H. Arakawa et al., "Efficient dye-sensitized solar cell sub-modules," Current Applied Physics, vol. 10, no. 2, pp. S157-S160, 2010.
[62] Y. Liu, H. Wang, H. Shen, and W. Chen, "The 3-dimensional dye-sensitized solar cell and module based on all titanium substrates," Applied Energy, vol. 87, no. 2, pp. 436-441, 2010.
[63] W. J. Lee, E. Ramasamy, and D. Y. Lee, "Effect of electrode geometry on the photovoltaic performance of dye-sensitized solar cells," Solar Energy Materials and Solar Cells, vol. 93, no. 8, pp. 1448-1451, 2009.
[64] Y.-D. Zhang et al., "How to design dye-sensitized solar cell modules," Solar Energy Materials and Solar Cells, vol. 95, no. 9, pp. 2564-2569, 2011.
[65] T.-C. Wei, Y.-H. Chang, S.-P. Feng, and H.-H. Chen, "A semi-experimental method for fast evaluation of the performance of grid-type dye-sensitized solar module," Int. J. Electrochem. Sci, vol. 8, pp. 9256-9263, 2013.
[66] X. Huang, Y. Zhang, H. Sun, D. Li, Y. Luo, and Q. Meng, "A new figure of merit for qualifying the fluorine-doped tin oxide glass used in dye-sensitized solar cells," Journal of Renewable and Sustainable Energy, vol. 1, no. 6, p. 063107, 2009.
[67] R. Sastrawan et al., "New interdigital design for large area dye solar modules using a lead-free glass frit sealing," Progress in Photovoltaics: Research and Applications, vol. 14, no. 8, pp. 697-709, 2006.
[68] R. Komiya, A. Fukui, N. Murofushi, N. Koide, R. Yamanaka, and H. Katayama, "Improvement of the conversion efficiency of a monolithic type dye-sensitized solar cell module," in Technical Digest, 21st International Photovoltaic Science and Engineering Conference, 2011, pp. 2C-5O.
[69] A. Hauch and A. Georg, "Diffusion in the electrolyte and charge-transfer reaction at the platinum electrode in dye-sensitized solar cells," Electrochimica Acta, vol. 46, no. 22, pp. 3457-3466, 2001.
[70] M. Adachi, M. Sakamoto, J. Jiu, Y. Ogata, and S. Isoda, "Determination of parameters of electron transport in dye-sensitized solar cells using electrochemical impedance spectroscopy," The Journal of Physical Chemistry B, vol. 110, no. 28, pp. 13872-13880, 2006.
[71] S. Yanagida, "Recent research progress of dye-sensitized solar cells in Japan," Comptes Rendus Chimie, vol. 9, no. 5-6, pp. 597-604, 2006.
[72] S. Venkatesan, I.-P. Liu, L.-T. Chen, Y.-C. Hou, C.-W. Li, and Y.-L. Lee, "Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System," ACS Appl Mater Interfaces, vol. 8, no. 37, pp. 24559-66, Sep 21 2016.
[73] C. Zhang et al., "Photoelectrochemical Analysis of the Dyed TiO2/Electrolyte Interface in Long-Term Stability of Dye-Sensitized Solar Cells," The Journal of Physical Chemistry C, vol. 116, no. 37, pp. 19807-19813, 2012.
[74] Furube, Akihiro, et al. "Lithium ion effect on electron injection from a photoexcited coumarin derivative into a TiO2 nanocrystalline film investigated by visible-to-IR ultrafast spectroscopy." The Journal of Physical Chemistry B, vol. 109, no. 34,pp. 16406-16414, 2005.