Study on transparent electromagnetic interference shielding using improved graphene by electroplating

다국어 초록 (Multilingual Abstract)

Recently, much attention has been paid to a flexible device due to development of the wearable device and foldable phone. However, it is reported that electromagnetic waves occur as driving pulse is applied to a touch screen panel of the flexible device and therefore the electromagnetic waves interference occurs between electronic components.
High electronic conductivity, transmittance, flexibility, thin thickness are needed in the flexible device for a transparent and flexible electromagnetic wave shielding. Indium tin oxide(ITO) is used for transparent electromagnetic wave shielding due to high conductivity and transmittance but it is easily broken due to low failure strain. In addition, alternative is needed due to price increase and resource depletion of the indium. Graphene is a candidate instead of the ITO but its theoretical properties were low due to defects. Therefore, in this study, defects of the graphene were improved by using selective electro-deposition for fabrication of the transparent and flexible electromagnetic wave shielding materials.
In this study, the graphene was synthesized by chemical vapor deposition and transferred on PET by thermal release tape. Ag was selected due to oxidation stability and high electronic conductivity. Parameters for optimized plating were current density (ASD), plating time and additive(PEI). A morphology of Ag particles were examined through SEM, OM and grain size and crystalline were confirmed by XRD. Ag binding energy was measured by XPS. In addition, selective plating at line defect, pin hole were confirmed through Raman spectroscope. In order to compare Ag plated graphene and defective graphene, four point probe, UV-vis, Attenuation were measured. Shielding effectiveness was measured by vector network analyzer in 1 – 18GHz.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Theoretical background 3
• 2.1. Graphene 3
• 2.1.1. Mechanical Cleavage 4
• 2.1.2. Chemical Exfoliation 4
• 2.1.3. Epitaxial Growth 5
• 2.1.4. Chemical Vapor Deposition 5
• 2.2. Electroplating 7
• 2.2.1. Electrochemistry Foundation 7
• 2.2.2. Electroplating 10
• 2.2.3. Current waveforms 12
• 2.3. Shielding 14
• 2.3.1. Shielding Effectiveness 14
• 2.3.2. Absorption loss 15
• 2.3.3. Reflection loss 16
• 3. Experimental 18
• 3.1. Synthesis of Graphene 18
• 3.2. Transferred Graphene 19
• 3.3. Electroplating 20
• 4. Results and Discussion 22
• 4.1. Synthesis of Graphene 22
• 4.2. Transferred Graphene to PET 23
• 4.2.1. Cu Etching 23
• 4.2.2. Lamination 24
• 4.3. Electroplating 25
• 4.3.1. Effect of Current density 25
• 4.3.2. Effect of Electroplating Time 26
• 4.3.3. Effect of Additive 28
• 4.4. Comparison Graphene with Ag Graphene 30
• 4.4.1. Ag Electroplating 30
• 4.4.2. Sheet Resistance 41
• 4.4.3. Shielding Effectiveness 42
• 4.4.4. Transmittance 44
• 5. Conclusion 46
• Reference 47
• Abstract 51