本研究將聚(3,4-乙烯二氧噻吩) (PEDOT)的單體3,4-乙烯二氧噻吩(EDOT)在聚(苯乙烯磺酸鹽)的溶液中進行電聚合，以製備 PEDOT:PSS複合薄膜。研究中探討溶液中EDOT和PSS的比例(1:0、1:1.25、1:6及1:10)、溶劑(PBS或HClO4)、電化學聚合法方式(定電位CP或循環電位DP)以及金前驅鹽的添加等變因對PEDOT:PSS薄膜特性的影響。首先利用定電位聚合(CP)對不同EDOT:PSS比率的探討中發現，PEDOT:PSS薄膜的導電度會隨著PBS溶液中PSS濃度增加而降低，因為PSS高分子不導電，此一結果亦代表溶液中EDOT相對PSS的比率越高，所得到的PEDOT越多。然而，PSS可與PEDOT進行摻雜，提升電極介面之電洞濃度及催化能力，故當溶液中加入PSS後，薄膜與電解液間的電荷傳輸阻力(Rct)值大幅下降，其中1:10系統表現最佳。開爾文探針(Kelvin probe)量測顯示費米能階的變化與摻雜程度之趨勢相符。此一實驗亦發現形貌及粗糙度在比例為1:1.25之系統最平整。在溶劑的效應上，若使用 HClO4 溶液取代PBS，並在EDOT:PSS為1:1.25條件下進行定電位聚合，所製得薄膜的導電度較PBS系統高，這結果顯示EDOT 在HClO4中有較大的反應速度，所以有較多的PEDOT產生。此外，因HClO4可降低PEDOT和PSS間的作用力，減少複合膜中PSS量亦是可能因素。因HClO4同樣可摻雜PEDOT，故膜的Rct下降。利用HClO4溶液所製得膜的粗糙度較PBS大，此一結果可歸因於其較快的聚合速度。在不同聚合方式的探討中，利用CP及DP法在PBS溶劑中以EDOT:PSS=1:6來比較。與CP法相比，DP法所製得膜的導電性較小，這是因為DP法的沉積速度較慢，增加PSS和PEDOT作用的可能性，因此膜中PSS含量提升，導電性及Rct都較低。與商業用PEDOT:PSS(1:6)利用旋塗法所製得的膜相比，本研究所製膜的導電度與Rct都較佳。當添加金前驅鹽並還原金奈米粒子於複合薄膜後，因膜中含有金粒子會與PEDOT作用，使PEDOT比例增加，故導電度提升且 Rct值小幅增加，此外，共同沉積的效應使表面平整性提升。

In this study, the monomer of poly(3,4-ethylenedioxythiophene) (PEDOT), which is 3,4-ethylenedioxythiophene (EDOT), was electropolymerized in a solution of poly(styrene sulfonate) to prepare PEDOT:PSS composite film. There are the characterization of PEDOT:PSS thin film by changing the ratio of EDOT and PSS in the solution (1:0, 1:1.25, 1:6 and 1:10), changing the solvent (PBS or HClO4), utilizing different electro-polymerization method (constant potential or cyclic potential, CP or DP) and adding gold precursor. First, by using constant potential method (CP) and different EDOT:PSS ratios, it is found that the conductivity of PEDOT:PSS film will decrease with the increase of PSS concentration in PBS solution. Due to the electric insulation of PSS polymer, this result also represents that the higher the ratio of EDOT to PSS in the solution, the more the amount of PEDOT in the film. However, PSS increases the doping degree of PEDOT chains, the charge density on the surface and enhances the catalytic ability. Hence, the value of Rct decreases sharply after adding PSS into solution. The variation of quasi-Fermi Level is consistent with the trend of the doping degree, as characterized by Kelvin Probe measurement. When the ratio of EDOT and PSS equals 1:1.25, the morphology and roughness are the smoothest. In terms of the solvent effect, the ratio of EDOT:PSS equals 1:1.25 and the electro-polymerization in HClO4 solution instead of PBS solution is carried out by CP method. The conductivity of the film in HClO4 system is higher than that in PBS system. This result shows that in HClO4 system the reaction rate is higher. In addition, it might be one possible factor that HClO4 solvent also reduces the amount of PSS interacting with PEDOT, so the amount of PEDOT gets larger. Meanwhile, the acid solvent also acts as a dopant. Hence, the value of Rct decreases. Due to higher reaction rate, the roughness of the film in HClO4 system is larger than that in PBS system. In the discussion of different polymerization methods, the methods are under EDOT:PSS=1:6 and in PBS solvent. Compared with the CP method, the conductivity of the film by the DP method is lower. This is because the rate of deposition by DP method is slower and it induces more PSS to interacting with PEDOT. Therefore, the PSS content in the film increases. The conductivity and Rct are lower. Compared with the commercial PEDOT:PSS (1:6) film made by spin coating, both the conductivity and Rct of the film in this research are better. When the gold precursor is added and the gold nanoparticles are reduced, the particles in the film would interact with PEDOT and increase the ratio of PEDOT in the film. So the conductivity increases and the value of Rct increases slightly. In addition, the co-deposition effect makes the surface smoother.

[1] Kiari, M., R. Berenguer, F. Montilla, and E. Morallón, "Preparation and Characterization of Montmorillonite/PEDOT-PSS and Diatomite/PEDOT-PSS Hybrid Materials. Study of Electrochemical Properties in Acid Medium," Journal of Composites Science. 4(2), 2020.
[2] Syu, B.S., "Investigation of solution heating and formic acid multiple treatment for improvement of the PEDOT:PSS film," National University of Kaohsiung. 2018.
[3] Chiang, C.K., C.R. Fincher, Y.W. Park, A.J. Heeger, H. Shirakawa, E.J. Louis, S.C. Gau, and A.G. MacDiarmid, "Electrical Conductivity in Doped Polyacetylene," Physical Review Letters. 39(17): p, 1098-1101, 1977.
[4] Cao, Y., P. Smith, and A.J. Heeger, "Counter-ion induced processibility of conducting polyaniline and of conducting polyblends of polyaniline in bulk polymers," Synthetic Metals. 48(1): p, 91-97, 1992.
[5] McCullough, R.D. and R.D. Lowe, "Enhanced electrical conductivity in regioselectively synthesized poly(3-alkylthiophenes)," Journal of the Chemical Society, Chemical Communications. (1): p, 70-72, 1992.
[6] Jen, K.-Y., G.G. Miller, and R.L. Elsenbaumer, "Highly conducting, soluble, and environmentally-stable poly(3-alkylthiophenes)," Journal of the Chemical Society, Chemical Communications. (17): p, 1346-1347, 1986.
[7] Roncali, J., R. Garreau, D. Delabouglise, F. Garnier, and M. Lemaire, "A molecular approach of poly(thiophene) functionalization," Synthetic Metals. 28(1): p, 341-348, 1989.
[8] Ocko, B.M., G.M. Watson, and J. Wang, "Structure and electrocompression of electrodeposited iodine monolayers on gold (111)," Journal of Physical Chemistry. 98:3: p, 897-906, 1994.
[9] Shirakawa, H., E.J. Louis, A.G. MacDiarmid, C.K. Chiang, and A.J. Heeger, "Synthesis of electrically conducting organic polymers: halogen derivatives of polyacetylene, (CH)," Journal of the Chemical Society, Chemical Communications. (16): p, 578-580, 1977.
[10] Lefrant, S., L.S. Lichtmann, H. Temkin, D.B. Fitchen, D.C. Miller, G.E. Whitwell, and J.M. Burlitch, "Raman scattering in (CH)x and (CH)x treated with bromine and iodine," Solid State Communications. 29(3): p, 191-196, 1979.
[11] De Surville, R., M. Jozefowicz, L.T. Yu, J. Pepichon, and R. Buvet, "Electrochemical chains using protolytic organic semiconductors," Electrochimica Acta. 13(6): p, 1451-1458, 1968.
[12] Diaz, A.F. and J.A. Logan, "Electroactive polyaniline films," Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 111(1): p, 111-114, 1980.
[13] Lapkowski, M. and E.M. Geniés, "Evidence of two kinds of spin in polyaniline from in situ EPR and electrochemistry: Influence of the electrolyte composition," Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 279(1): p, 157-168, 1990.
[14] Yoon, H., B.S. Jung, and H. Lee, "Correlation between electrical conductivity, thermal conductivity, and ESR intensity of polyaniline," Synthetic Metals. 41(1): p, 699-702, 1991.
[15] Bhattacharya, A., A. De, and S.N. Bhattacharyya, "Preparation of polypyrrole composite with acrylic acid-grafted tetrafluorothylene-hexafluoropropylene (Teflon-FEP) copolymer," Synthetic Metals. 65(1): p, 35-38, 1994.
[16] Garnier, F., G. Tourillon, M. Gazard, and J.C. Dubois, "Organic conducting polymers derived from substituted thiophenes as electrochromic material," Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 148(2): p, 299-303, 1983.
[17] Hotta, S., M. Soga, and N. Sonoda, "Novel organosynthetic routes to polythiophene and its derivatives," Synthetic Metals. 26(3): p, 267-279, 1988.
[18] Kobayashi, M., N. Colaneri, M. Boysel, F. Wudl, and A.J. Heeger, "The electronic and electrochemical properties of poly(isothianaphthene) [J. Chem. Phys. 82, 5717 (1985)]," The Journal of Chemical Physics. 83(11): p, 6061-6061, 1985.
[19] Boara, G. and M. Sparpaglione, "Synthesis of polyanilines with high electrical conductivity," Synthetic Metals. 72(2): p, 135-140, 1995.
[20] Harsányi, G., "Polymer films in sensor applications: a review of present uses and future possibilities," Sensor Review. 20(2): p, 98-105, 2000.
[21] Groenendaal, L., F. Jonas, D. Freitag, H. Pielartzik, and J.R. Reynolds, "Poly(3,4-ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future," Advanced Materials. 12(7): p, 481-494, 2000.
[22] Wang, L., W. Mao, D. Ni, J. Di, Y. Wu, and Y. Tu, "Direct electrodeposition of gold nanoparticles onto indium/tin oxide film coated glass and its application for electrochemical biosensor," Electrochemistry Communications. 10(4): p, 673-676, 2008.
[23] Kumar, S.S., J. Mathiyarasu, K.L.N. Phani, and V. Yegnaraman, "Simultaneous determination of dopamine and ascorbic acid on poly (3,4-ethylenedioxythiophene) modified glassy carbon electrode," Journal of Solid State Electrochemistry. 10(11): p, 905-913, 2006.
[24] Bello, A., M. Giannetto, G. Mori, R. Seeber, F. Terzi, and C. Zanardi, "Optimization of the DPV potential waveform for determination of ascorbic acid on PEDOT-modified electrodes," Sensors and Actuators B: Chemical. 121(2): p, 430-435, 2007.
[25] Guzinski, M., et al., "PEDOT(PSS) as Solid Contact for Ion-Selective Electrodes: The Influence of the PEDOT(PSS) Film Thickness on the Equilibration Times," Anal Chem. 89(6): p, 3508-3516, 2017.
[26] Reza, K.M., et al., "Tailored PEDOT:PSS hole transport layer for higher performance in perovskite solar cells: Enhancement of electrical and optical properties with improved morphology," Journal of Energy Chemistry. 44: p, 41-50, 2020.
[27] Xia, Y., J. Fang, P. Li, B. Zhang, H. Yao, J. Chen, J. Ding, and J. Ouyang, "Solution-Processed Highly Superparamagnetic and Conductive PEDOT:PSS/Fe3O4 Nanocomposite Films with High Transparency and High Mechanical Flexibility," ACS Applied Materials & Interfaces. 9(22): p, 19001-19010, 2017.
[28] Brull, M.B., "Development of electrochemical sensors for hydrogen peroxide determination," Universitat Rovira i Virgili. p, 72, 2020.
[29] X. Crispin, F.L.E.J., A. Crispin, P. C. M. Grim, P. Andersson, A. Volodin, C. van Haesendonck, M. Van der Auweraer, W. R. Salaneck, and M. Berggren, "The Origin of the High Conductivity of Poly(3,4-ethylenedioxythiophene)−Poly(styrenesulfonate) (PEDOT−PSS) Plastic Electrodes," Chem. Mater. . 18, 18: p, 4354-4360, 2006.
[30] Castagnola, V., C. Bayon, E. Descamps, and C. Bergaud, "Morphology and conductivity of PEDOT layers produced by different electrochemical routes," Synthetic Metals. 189: p, 7-16, 2014.
[31] Fan, Z., P. Li, D. Du, and J. Ouyang, "Significantly Enhanced Thermoelectric Properties of PEDOT:PSS Films through Sequential Post-Treatments with Common Acids and Bases," Advanced Energy Materials. 7(8): p, 1602116, 2017.
[32] Rumbau, V., J.A. Pomposo, A. Eleta, J. Rodriguez, H. Grande, D. Mecerreyes, and E. Ochoteco, "First Enzymatic Synthesis of Water-Soluble Conducting Poly(3,4-ethylenedioxythiophene)," Biomacromolecules. 8(2): p, 315-317, 2007.
[33] Mumtaz, M., A. de Cuendias, J.-L. Putaux, E. Cloutet, and H. Cramail, "Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic Media," Macromolecular Rapid Communications. 27(17): p, 1446-1453, 2006.
[34] Bu, H.B., G. Gotz, E. Reinold, A. Vogt, R. Azumi, J.L. Segura, and P. Bauerle, ""Click"-modification of a functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) soluble in organic solvents," Chem Commun (Camb). 48(21): p, 2677-9, 2012.
[35] 王婷儀, 電聚合官能化石墨烯/PEDOT-PSS之複合薄膜應用於染料敏化太陽能電池, 成功大學化學工程學系. 2017.
[36] Du, X. and Z. Wang, "Effects of polymerization potential on the properties of electrosynthesized PEDOT films," Electrochimica Acta. 48(12): p, 1713-1717, 2003.
[37] Krische, B. and M. Zagorska, "Overoxidation in conducting polymers," Synthetic Metals. 28(1): p, 257-262, 1989.
[38] Patra, S., K. Barai, and N. Munichandraiah, "Scanning electron microscopy studies of PEDOT prepared by various electrochemical routes," Synthetic Metals. 158(10): p, 430-435, 2008.
[39] Banerji, A., S. Kirchmeyer, K. Meerholz, and F. Scharinger, "Teaching Organic Electronics - Part II: Quick & Easy Synthesis of the (Semi-)Conductive Polymer PEDOT: PSS in a Snap-Cap Vial," World Journal of Chemical Education. 7(2): p, 166-171, 2019.
[40] Jönsson, S.K.M., J. Birgerson, X. Crispin, G. Greczynski, W. Osikowicz, A.W. Denier van der Gon, W.R. Salaneck, and M. Fahlman, "The effects of solvents on the morphology and sheet resistance in poly(3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT–PSS) films," Synthetic Metals. 139(1): p, 1-10, 2003.
[41] Kroon, R., D.A. Mengistie, D. Kiefer, J. Hynynen, J.D. Ryan, L. Yu, and C. Muller, "Thermoelectric plastics: from design to synthesis, processing and structure-property relationships," Chem Soc Rev. 45(22): p, 6147-6164, 2016.
[42] Wieland, M., C. Malacrida, Q. Yu, C. Schlewitz, L. Scapinello, A. Penoni, and S. Ludwigs, "Conductance and spectroscopic mapping of EDOT polymer films upon electrochemical doping," Flexible and Printed Electronics. 5(1), 2020.
[43] Wen, Y. and J. Xu, "Scientific Importance of Water-Processable PEDOT-PSS and Preparation, Challenge and New Application in Sensors of Its Film Electrode: A Review," Journal of Polymer Science Part A: Polymer Chemistry. 55(7): p, 1121-1150, 2017.
[44] Kawano, K., R. Pacios, D. Poplavskyy, J. Nelson, D.D.C. Bradley, and J.R. Durrant, "Degradation of organic solar cells due to air exposure," Solar Energy Materials and Solar Cells. 90(20): p, 3520-3530, 2006.
[45] Kong, F., C. Liu, H. Song, J. Xu, Y. Huang, H. Zhu, and J. Wang, "Effect of solution pH value on thermoelectric performance of free-standing PEDOT:PSS films," Synthetic Metals. 185-186: p, 31-37, 2013.
[46] Wang, Z., Z. Wang, H. Zhang, X. Duan, J. Xu, and Y. Wen, "Electrochemical sensing application of poly(acrylic acid modified EDOT-co-EDOT):PSS and its inorganic nanocomposite with high soaking stability, adhesion ability and flexibility," RSC Advances. 5(16): p, 12237-12247, 2015.
[47] Zhang, J., J. Xu, Y. Wen, Z. Wang, H. Zhang, and W. Ding, "Voltammetric determination of phytoinhibitor maleic hydrazide using PEDOT:PSS composite electrode," Journal of Electroanalytical Chemistry. 751: p, 65-74, 2015.
[48] Greczynski, G., T. Kugler, M. Keil, W. Osikowicz, M. Fahlman, and W.R. Salaneck, "Photoelectron spectroscopy of thin films of PEDOT–PSS conjugated polymer blend: a mini-review and some new results," Journal of Electron Spectroscopy and Related Phenomena. 121(1): p, 1-17, 2001.
[49] Yu, Z., Y. Xia, D. Du, and J. Ouyang, "PEDOT:PSS Films with Metallic Conductivity through a Treatment with Common Organic Solutions of Organic Salts and Their Application as a Transparent Electrode of Polymer Solar Cells," ACS Applied Materials & Interfaces. 8(18): p, 11629-11638, 2016.
[50] Park, H., S.H. Lee, F.S. Kim, H.H. Choi, I.W. Cheong, and J.H. Kim, "Enhanced thermoelectric properties of PEDOT:PSS nanofilms by a chemical dedoping process," J. Mater. Chem. A. 2(18): p, 6532-6539, 2014.
[51] 黃暄益, 郭., 多型態的金奈米材料, 國立清華大學化學系. 2006.
[52] Cheng, W., S. Dong, and E. Wang, "Gold Nanoparticles as Fine Tuners of Electrochemical Properties of the Electrode/Solution Interface," Langmuir. 18(25): p, 9947-9952, 2002.
[53] Cheng, W., X. Han, E. Wang, and S. Dong, "Interdigited Phospholipid/Alkanethiol Bilayers Assembled on APTMS-Supported Gold Colloid Electrodes," Electroanalysis. 16(1-2): p, 127-131, 2004.
[54] Zhang, J. and M. Oyama, "Gold nanoparticle arrays directly grown on nanostructured indium tin oxide electrodes: Characterization and electroanalytical application," Analytica Chimica Acta. 540(2): p, 299-306, 2005.
[55] Chang, G., M. Oyama, and K. Hirao, "Seed-Mediated Growth of Palladium Nanocrystals on Indium Tin Oxide Surfaces and Their Applicability as Modified Electrodes," The Journal of Physical Chemistry B. 110(41): p, 20362-20368, 2006.
[56] Umar, A.A. and M. Oyama, "A cast seed-mediated growth method for preparing gold nanoparticle-attached indium tin oxide surfaces," Applied Surface Science. 253(4): p, 2196-2202, 2006.
[57] Harwell, J.R., T.K. Baikie, I.D. Baikie, J.L. Payne, C. Ni, J.T. Irvine, G.A. Turnbull, and I.D. Samuel, "Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy," Phys Chem Chem Phys. 18(29): p, 19738-45, 2016.