Artificial Network Structuring of 1-Dimensional Materials for Electrochromic Devices and Transparent Heaters

다국어 초록 (Multilingual Abstract)

Artificial Network Structuring of 1-Dimensional Materials for Electrochromic Devices and Transparent Heaters Gwang-Myeong Go Dept. of Materials Science and Chemical Engineering The Graduate School of Hanyang University Recently, transparent electrode has driven many research developments in the optoelectronics , opening up new possibilities for stability and convenience of future industries. High electrical conductivity and optical properties enabled excellent growth in automobile and display market. However, there are still break-throughs that should be overcome for next generation camera module and device. In this study, we presented innovative flexible transparent electrodes fabrication and their application performance. The dissertation is composed of 5 chapters. In the chapter 1 (Introduction), the kind of transparent electrode materials, methods for synthesizing core-shell structures, and several coating techniques to fabricate transparent electrodes were presented. In the chapter 2, A silver@gold core@shell nanowire structure synthesized by epitaxial growth, a simple deposition technique via complex ions, is presented. At first, the growth of a uniform and homogeneous gold shell on silver nanowire through sulfite complexes was demonstrated. Uniform gold shells could be synthesized by adjusting the epitaxial growth depending on pH and the ratio of sulfate complexes was presented. As-synthesized silver@gold core@shell nanowires exhibited chemical resistance to hydrogen peroxide solution and nitric acid solution. In the chapter 3, grid-patterned transparent heater device was presented using silver@gold nanowire and polydimethylsiloxane (pdms) mold. Grid pattern is based on the capillary effect using micromold with various line widths and pitches. Transparent electrodes with stripe patterns and grid patterns were fabricated, and their transmittance and electrical conductivity were compared. It was obviously verified that the transparent heater with grid pattern is suitably operable to remove fog and frost. In chapter 4, the major subject was to demonstrate the utilization of new type mesh structure, called ‘self-assembly cell structure’, and potential application of flexible electrochromic device. The self-assembly cell structure is based on the difference in vapor pressure of each solvent and the Marangoni effect, which exhibit optimal electrical conductivity and optical property with a small amount of content. The self-assembly cell structure made of silver@gold nanowires has improved electrical conductivity through junctions between nanowires using an intense pulse laser (IPL) process. Tungsten oxide was deposited on the as-fabricated transparent electrode, and an electrochromic device exhibiting excellent electrochromic properties was fabricated. It was also demonstrated that a flexible electrochromic device based on silver@gold nanowires showed sufficient potential. In the last chapter, the finding and conclusions were summarized.

목차 (Table of Contents)

• Chapter1. Introduction 1
• 1.1 Materials of Transparent Electrode 1
• 1.1.1 Indium Tin Oxide (ITO) 2
• 1.1.2 Carbon Nanotubes (CNTs) 4
• 1.1.3 Graphene 5
• 1.1.4 PEDOT:PSS 6
• 1.1.5 Silver Nanowires (AgNWs) 7
• 1.2 Various Synthesis Methods of Core@Shell Ag Nanowire 10
• 1.2.1 Electroplating 11
• 1.2.2 Chemical Reduction 12
• 1.3 Flexible Transparent Electrode 14
• 1.3.1 Optical Properties of Transparent Electrode 15
• 1.3.2 Electrical properties of transparent electrode 17
• 1.3.3 Flexibility Properties of Transparent Electrode 19
• 1.4 Fabrication Method for Flexible Transparent Electrode 21
• 1.4.1 Vacuum filtration 22
• 1.4.2 Spray coating 23
• 1.4.3 Spin coating 23
• 1.4.4 Dip coating 24
• 1.4.5 Meyer rod coating 25
• 1.5 Type of metal-based flexible transparent electrode 26
• 1.5.1 Ultrathin Metal Film 26
• 1.5.2 Metal Nanowire Network 28
• 1.5.3 Metal Mesh 29
• 1.6 Application of Flexible Transparent Electrode 30
• 1.6.1 Electrochromic Application 31
• 1.6.2 Transparent Film Heater 32
• 1.6.3 Solar cells 34
• 1.6.4 Touch screens 35
• 1.6.5 Other applications 35
• 1.7 The Scope of the Thesis 36
• 1.8 Reference 38
• Chapter 2. Epitaxial synthesis of Ag@Au core@shell nanowire for oxidation prevention 48
• 2.1 Introduction 48
• 2.2 Experimental section 50
• 2.2.1 Materials 50
• 2.2.2 Synthesis of Ag@Au core@shell nanowire 50
• 2.2.3 Characterization 51
• 2.3 Results and discussion 51
• 2.4 Conclusion 60
• 2.5 Reference 61
• Chapter 3. Transparent heater with grid pattern using nanowire for frost removal 64
• 3.1 Introduction 64
• 3.2 Experimental section 67
• 3.2.1 Materials 67
• 3.2.2 Preparation of Ag@Au NWs ink 67
• 3.2.3 Fabrication of PDMS mold 68
• 3.2.4 Fabrication of transparent heater with grid pattern using nanowire 68
• 3.3 Results and discussion 69
• 3.4. Conclusion 78
• 3.5 Reference 79
• Chapter 4. Flexible electrochromic devices with self-assembly cell structure 82
• 4.1 Introduction 82
• 4.2 Experimental section 85
• 4.2.1 Materials 85
• 4.2.2 Preparation of self-assembly Ag@Au NWs ink 85
• 4.2.3 Fabrication of self-assembly Ag@Au NWs transparent electrode 86
• 4.2.4 Prepared of tungsten oxide sol 86
• 4.2.4 Fabrication of Flexible electrochromic device 87
• 4.2.5 Characterization 87
• 4.3 Results and discussion 88
• 4.4 Conclusion 99
• 4.5 Reference 100
• Chapter 5. Summary 105
• 국문요지 108