本論文染料敏化太陽能電池，使用N719染料-TiO2工作電極、碘離子電解液與白金對電極光電轉換效率可達3.2%，然而染料敏化太陽能電池使用奈米白金混摻導電高分子PEDOT:PSS導電奈米複合薄膜對電極已可得光電轉換效率3.02%。藉由循環伏安法，比例為22Wt%奈米白金於PEDOT:PSS導電高分子中且經1200C， 20分鐘熱處理，厚度為450 nm之導電奈米複合薄膜對其碘離子電解液有最佳氧化還原特性。由SEM與AFM可發現具有表面孔洞的導電奈米複合薄膜與粗糙度的增加，皆可提升PEDOT:PSS-Pt導電奈米複合薄膜對碘離子電解液的氧化還原能力。熱處理最佳化是必須的,過高溫之熱處理會破壞PEDOT:PSS庫倫作用力而使導電度下降，過低溫熱處理將無法完全移除溶劑。同樣地，膜厚也影響PEDOT:PSS-Pt導電奈米複合薄膜對電極氧化還原表現，藉由極化曲線可得知較厚之導電奈米複合薄膜具有較高面電阻值，然而膜厚較薄之導電奈米複合薄膜又易出現pin hole。22Wt%奈米白金於PEDOT:PSS奈米複合薄膜再經由交流阻抗分析證實其對碘離子電解液具有最小之電子交換阻抗。最後經由電化學Randles-Sevcik法證實PEDOT:PSS-Pt導電奈米複合薄膜對碘離子的氧化還原為質傳控制，代表碘離子的氧化還原速率決定步驟為碘離子之本身擴散。
染料敏化太陽能電池使用PEDOT:PSS-Pt導電奈米複合薄膜對電極其開路電壓發現有下降之趨勢當使用22Wt%奈米白金於PEDOT:PSS奈米複合薄膜中，其可歸因於質傳過電壓損失與電子交換過電壓損失之存在，當短路電流相對提升時，由歐姆定律可得知其過電壓損失昰增加的。填充因子有增加的趨勢，當奈米白金量的使用量增加時，這與 PEDOT:PSS-Pt導電奈米複合薄膜面電阻質之改善有關。

The application of the platinum nanoparticles added in PEDOT:PSS conducting polymer as the counter electrode for DSSC, which was made by depositing PEDOT:PSS-Pt on FTO substrate by spin coating method, following the low temperature heat process was conducted, and thus the PEDOT:PSS-Pt counter electrode assembled with N719-TiO2 photo-electrode and employed I-/I3- mediator as electrolyte. The heat process and film thickness influence the PEDOT:PSS-Pt counter electrode electrocatalytical activity significantly. The thickness 450 nm of conductive PEDOT:PSS matrix contained 22 wt% platinum nanoparticles after 120 0C heat process exhibited best photo-conversion efficiency 3.02% under Am 1.5 illumination in comparison with the device assembled with thermal decomposition of H2PtCl6 counter electrode which photo-conversion efficiency 3.2% was obtained. The SEM and AFM images proved that the presence of pores and the increased surface roughness enhancing the cell performance remarkably. Impedance measurement demonstrated that the charge transfer resistance was improved as increasing the amount of platinum nanoparticles. Additionally, the diffusion control was also confirmed when use of the PEDOT:PSS-Pt counter electrode in I-/I3- mediator electrolyte by Randles-Sevcik method.
In this work, the material cost and energy-consuming of PEDOT:PSS-Pt counter electrode were drastically reduced compared with the thermal decomposition of H2PtCl6 counter electrode. The DSSC using PEDOT:PSS-Pt counter electrode had obtained acceptable performance, which suggested that the nanocomposite film PEDOT:PSS-Pt is a promising candidate to replace of the platinum for DSSC counter electrode and to develop a bifacial flexible DSSC.

Table of Contents
Page
Chapter 1: Introduction......................................................................1
 1.1 Background of DSSC Counter Electrode and Research Object................................1
 1.2 Theory of DSSC and Development.....................................................................3
Chapter 2: Literature Review……………………………...……............................7
2.1 The Pt Counter Electrode of DSSC………………………………….…..........7
2.1.1 DSSC Using Pt Counter Electrode……………………………………..…...........7
2.1.2 Characteristics and Preparation of Platinum Nanoparticles…………..................10
2.2 Introduction of Poly(3,4-etheylenedioxytiophene):Poly(styrenesulfonate)……….13
2.2.1 Poly(3,4-etheylenedioxytiophene):Poly(styrenesulfonate)...................................13
2.2.2 Conductivity Modification on PEDOT:PSS…......….........................…...............18
2.2.3 Applications of PEDOT:PSS............…………………………...............................20
Chapter 3 Experiments……………………………………................23
3.1 Materials………………………………………….......................…..……...........23
3.2 Experimental Procedures………………….…......................................................26
3.3 Characterizations…………..…..……………….…...............................................28
Chapter 4 Results and Discussion……………………………...........................33
4.1 The Synthesis of Platinum Nanoparticles………………………………….…..........33
4.1.1 Optimization of Synthesis of Platinum Nanoparticles.........................................33
4.1.2 Morphology and Characterization…....................................................................36
4.2 Preparation and Characterization of PEDOT:PSS-Pt Nanocomposite film...................40
4.2.1 The Influence of Pt Nanoparticles Contents on the PEDOT:PSS Matrix stability...40 
4.2.2 Thermal Gravimetric Analysis……......................................................................43 
4.2.3 The Structure of PEDOT:PSS-Pt Nanocomposite Film………............................45
4.2.4 Optimization of the Coating Process………........................................................49 
4.2.5 Optimization of the Heating Process……............................................................51
4.2.6 The Influence of Pt Nanoparticle Contents in the PEDOT:PSS Nanocomposite Film Electrocatalytic Activity................................................................................53
4.2.7 The Morphology of the PEDOT:PSS-Pt Nanocomposite Film............................54
4.2.8 The Influence of Crystal Structure of PEDOT:PSS-Pt Nanocomposite film on    Conductivity...........................................................................................................62 
4.3 Characterization of PEDOT:PSS-Pt Nanocomposite Counter Electrode....................64
4.3.1 The Influence of Charge Transfer Resistance on the PEDOT:PSS-Pt Nanocomposite Counter Electrodes Performance……………................................................64 
4.3.2 The Influence of Mass Transfer Resistance on the PEDOT:PSS-Pt Nanocomposite Counter Electrodes Performance….................................................................66 
4.3.3 Photo-Conversion Efficiency…..............................................................................70
Chapter 5 Conclusion.............................................................................................73 
Reference.............................................................................................................................75
Appendix..............................................................................................................................80



























LIST OF FIGURES
Figure 1-1 The energy level of DSSC with  and without  illumination. 
.................................................3
Figure 1-2 Series tandem DSSC............................................................................................4
Figure 1-3 Monolithic type.......... ................................. .......................................................5
Figure 1-4 Centrosymmetric (w-type) ................................. ................................................5
Figure 1-5 Centroasymmetric type.......... ........................................ ....................................6
Figure 1-6 Parallel DSSC module.......... ................................. ........... ........... .....................6
Figure 2-1 SEM pictureof sputtering Pt on TCO........... ..........................................................9
Figure 2-2 Mechanism of triorganohydroborate reduction method... ....................................10
Figure 2-3 The reduction potential of metal species in ethylene at both carbon electrode and platinum electrode at room temperature. The oxidation potential of ethylene glycol is also given......... ....................................................................................12
Figure 2-4 The Poly(3,4-ethylenedioxythiophene).... .................................. ....................15
Figure 2-5 The non-conductive (reduced) state and conductive (oxidized) state..............15
Figure 2-6 The gel particles of PPEDOT:PSS dispersed in the water....... .......................15
Figure 2-7 The PEDOT:PSS chemical synthesis mechanism........ ........... .......................16
Figure 2-8 The interaction of PEDOT with the PSS chains......... .....................................16
Figure 2-9 The bond alternation of polyacetylene................. ........... ........... .....................16
Figure 2-10 The sigma bond with localized electron polyethylene..... ........... .....................16
Figure 2-11 The π*-π band gap decreases with the conjugated electron length....................17
Figure 2-12 The three mechanism carrier mobility in conjugated polymer..........................17
Figure 2-13 The proposed three stage thermal degradation mechanism of PEDOT:PSS....18
Figure 2-14 The OLED structure....... ................................. ...............................................21
Figure 3-1 The DSSC fabrication with PEDOT:PSS-Pt nanocomposite counter electrode.27
Figure 3-2 Three-electrode system for cyclic voltammetry measurement...........................28
Figure 3-3 The symmetric device used for the EIS measurement.. ........................................30
Figure 3-4 An RC element in Nyquist plot..............................................................................30
Figure 3-5 An RC element in series with resistance in Nyquist plot.......................................30
Figure 3-6 The symmetric device used for the J-V measurement...........................................32
Figure 4-1 Nucleation and growth mechanism base on LaMer’s model. (a) poly-disperse particles. (b) mono-disperse particles.................................................................34
Figure 4-2 The polyol-derived Pt particle size as a function of reacting temperature.......35
Figure 4-3 TEM images of platinum nanoparticles synthesized at 90 °C for 4 h. (a) without removing of water. (b) magnified part section of (a)...........................................37
Figure 4-4 TEM images of platinum nanoparticles synthesized at 90 °C for 4 h. with removing of water by concentration at 60 0C, 0.5h.............................................38
Figure 4-5 The UV-Vis spectrum absorption of (a) PtCl6- and (b) Pt nanoparticles. The concentration were both 0.0001M.......................................................................39
Figure 4-6 The FTIR spectrum of PEDOT precipitate...........................................................41
Figure 4-7 The SEM images of PEDOT-Pt nanocomposite precipitates...............................41
Figure 4-8 The representation of platinum nanoparticles incorporated in high and low weight ratio of [PSS]/[PEDOT] matrix................................................................42
Figure 4-9 The (a) weight loss diagram for PSS, PEDOT:PSS and PEDOT:PSS blended with platinum nanoparticles and (b) differential thermogravimetry..................44
Figure 4-10 The TEM images of pristine PEDOT:PSS...........................................................46
Figure 4-11 The TEM images of PEDOT:PSS prepared with ethylene glycol solvent........47
Figure 4-12 TEM images of PEDOT:PSS prepared with 22 Wt% platinum nanoparticles....48
Figure 4-13 The Proposed structure of PEDOT:PSS-Pt nanocomposite.................................48
Figure 4-14 The effect of the film thickness and various platinum contents on the I3- ion reduction current density peaks.... ....................................................................50
Figure 4-15 The J-V characteristic of different thickness of PEDOT:PSS prepared 22 Wt% Pt............................................................................................................................50
Figure 4-16 The influence of heat treatment for 20 min. on the films’ reduction current density peaks... ................................. .........................................................52
Figure 4-17 The CV of I-/I3- redox reactions at PEDOR:PSS-Pt counter electrodes with various platinum nanoparticles loading. The electrolyte was acetonitrile solution containing 10 mM LiI, 1mM I2 and 0.1M LiClO4 (supporting electrolyte). The area of the PEDOT:PSS-Pt modified electrode was 2 cm2. the scan rate = 20 mv/s............................................................................................54
Figure 4-18 The EDAX of the PEDOT:PSS-Pt nanocomposite prepared with 22 Wt% of Pt.. ................................. ................................. ...................................................56
Figure 4-19 The SEM images of the PEDOT:PSS-Pt 22 Wt% film with 120oC heat treatment, 450 nm thickness..................................................................................................57
Figure 4-20 The SEM images of pristine PEDOT:PSS film with 120oC heat treatment (a)100K and (b)150K..........................................................................................................57
Figure 4-21 The surface of PEDOT:PSS prepared using 50 Wt% ethylene glycol with 120oC heat treatment, 450 nm thickness.........................................................................58
Figure 4-22 The AFM images of PEDOT:PSS-ethylene glycol film with 120oC heat treatment, 450 nm thickness..................................................................................................59
Figure 4-23 The AFM images of PEDOT:PSS film with 120oC heat treatment.....................59 
Figure 4-24 The AFM image of TEC7 substrate.....................................................................60
Figure 4-25 The SEM image of TEC7 substrate......................................................................60
Figure 4-26 The AFM images of (a) PEDOT:PSS-EG, (b) 5.5 Wt % Pt, (c) 11 Wt% Pt, (d) 22 Wt % Pt with heat treatment at 120 oC for 20 min...............................................61
Figure 4-27 The XRD spectra of(a) 5.5 Wt% Pt (b) 11Wt% Pt, (c) 22 Wt% Pt, (d) thermal decomposition of H2PtCl6.........................................................63
Figure 4-28 The J-V characteristic of PEDOT:PSS prepared 50 wt% ethylene glycol and 22 wt% platinum nanoparticles, both of two layers are 450 nm. .............................63
Figure 4-29 The Nyquist plot of PEDOT:PSS electrode prepared with different metallic platinum nanoparticle content............................................................................65
Figure 4-30 The Equivalent circuit diagram fits the observed impedance result in Fig. 4-29...65
Figure 4-31 The mediator redox mechanism of DSSC............................................................66
Figure 4-32 The CV of iodide species on PEDOT:PSS-EG with various scan rate in acetonitrile solution of 10 mM LiI, 1mM I2, and 1 M LiClO4...........................68
Figure 4-33 The relationship between cathodic peak currents and anodic peak currents as a function of the scan rate1/2 of PEDOT:PSS- EG..................................................68
Figure 4-34 The CV of iodide species on PEDOT:PSS- Pt 22wt% with various scan rate in acetonitrile solution of 10 mM LiI, 1mM I2, and 1 M LiClO4...........................69
Figure 4-35 The relationship between cathodic peak currents and anodic peak currents as a function of the scan rate1/2 of PEDOT:PSS-Pt 22%.............................................69
Figure 4-36 The J-V characteristics of DSSC using PEDOT:PSS with various metallic platinum nanoparticles content as counter electrode...........................................71
Figure 4-37 The dependence of (a) Voc, (b) Jsc, (c) FF and (d) PCE on the different weight ratio of [Pt]/[PEDOT:PSS]...........................................................................................72






LIST OF TABLES
Page
Table 2-1 Results of the impedance measurement on different Pt deposition method..............9
Table 4-1 Synthesis parameters and products of the polyol process, concentration 0.01M, reaction time 4 h.......................................................................................................35 
Table 4-2 Specification of commercial PEDOT:PSS...............................................................42
Table 4-3 The data for electrochemical reversibility of I-/I3- mediator carried out by CV.......54
Table 4-4 The relationship of RMS of film in various Pt content.......................................61
Table 4-5 The DSSC performance using the PEDOT:PSS-Pt nanocompositecounter electrode...................................................................................................................72














LIST OF Appendixes
Page

Appendix 1 Platinum particle synthesized at 110 °C for 4 h................................................80
Appendix 2 platinum nanoparticles synthesized at90 °C .................................................80
Appendix 3 platinum nanoparticles synthesized at 85 °C for 4 h.....................................80
Appendix 4 The DLS of PEDOT:PSS primary article.....................................................81
Appendix 5 The XRD spectra of (a) FTO.......................................................................81
Appendix 6 Sputtering Pt (100nm) cathodic peaks and anodic peaks as a function of scan.82
Appendix 7 The characterization of I-V curve...................................................................82
Appendix 8 The DSSC performance used PEDOT:PSS-Pt counter electrode without EG correcting...........................................................................................................83
Appendix 9 The cyclic voltammetry experiment for PEDOT:PSS-Pt (5.5 Wt% and 11 Wt% Pt without EG corrected)........................................................................................83
Appendix 10 The influence of Pt content on the film conductivity…………………………...83

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