The Characterization of Graphene Paper for Flexible Electronics Application
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Transcript of The Characterization of Graphene Paper for Flexible Electronics Application
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The Characterization of Graphene Paper for Flexible Electronics Application
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Introduction Methodology Results Conclusions
Introduction
What is Graphene?
Chemical Definition
Why Graphene?
Motivation
Material Synthesis
Graphene Paper
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Introduction Methodology Results Conclusions
What is Graphene?
• Chemical definition
• Exceptional Properties
• Why graphene?
• Low cost
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Introduction Methodology Results Conclusions
Motivations for This Work
• Lack of thorough understanding Experimental modeling
• Single layer graphene Not implementable for large scale applications Large scale graphene products are needed.
• Problems with current large scale methods Geometry limitations, structural flaws A method with no geometry limitation and with better properties
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Introduction Methodology Results Conclusions
Material Synthesis
• Mechanical Exfoliation Not scalable• Reduction of Graphene Oxide Functionalized groups• Chemical Vapor Deposition (CVD) Hazardous by-
products, extremely high temperatures• Liquid Phase Exfoliation High yield production, no
Functionalized groups
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Introduction Methodology Results Conclusions
Graphene Paper• Graphene paper = Graphene + Hierarchical structures
[1]
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Introduction Methodology Results Conclusions
Graphene Paper
• Improved strength to toughness ratio
• Low density for a given volume element.
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Introduction Methodology Results Conclusions
A Quick Literature Review• Chen (2008) Vacuum filtration, conductivity, biomedically
compatible for cell growth
• Yilun (2011) Dependence of mechanical properties on the cross link type
• Weng (2011) Graphene paper + cellulose fibers for supercapacitors.
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Introduction Methodology Results Conclusions
Methodology
Graphene/EC powder/ink
AFM
Sample fabrication
Electrical measurement
setup
Mechanical Tests
Cyclic Bending Test
Adhesion TestSupercapacitance
test setup
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Introduction Methodology Results Conclusions
Graphene/Ethyl Cellulose (EC) Powder/Ink Development
• Graphene/EC powder synthesis
• Ink Development 3 ml terpineol + 7 ml cyclohexanane
• EC Capping agent Promote dispersibility
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Introduction Methodology Results Conclusions
Sample Fabrication• Adjusted viscosity Uniform graphene paper
coating
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Introduction Methodology Results Conclusions
Atomic Force Microscopy (AFM)
• To measure the ballpark of the thickness
• Areas near the edges
• AFM in tapping mode
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Introduction Methodology Results Conclusions
Electrical Resistance measurement setup• Linear electrical field Simplifies the math
• In situe tests portable fixture
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Introduction Methodology Results Conclusions
Electrical Resistance measurement setup
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Introduction Methodology Results Conclusions
Mechanical Tests
• Adhesion test
• Cyclic bending test
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Introduction Methodology Results Conclusions
Cyclic Bending
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Introduction Methodology Results Conclusions
Adhesion Test Setup
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Introduction Methodology Results Conclusions
Supercapacitance setup• Electrode preparation
• Three electrode system setup
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Introduction Methodology Results Conclusions
Results and Discussion
Thickness measurement
Sheet resistance analysis
Modeling , R(T,t,C)
Cyclic bending
Adhesion test
Raman spectroscopy
Super capacitance
measurement
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Introduction Methodology Results Conclusions
Thickness measurement• 3 mg/ml ~ 200 nm
• 1 mg/ml ~ 90 nm
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Introduction Methodology Results Conclusions
Sheet Resistance Analysis• Experimental variables and constants
• and •
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Introduction Methodology Results Conclusions
Sheet Resistance Analysis• Very low resistivity!
• Why ? The presence of EC as a polysaccharide
TGA analysis on graphene/EC powder showing (a) mass changes versus temperature and (b) the differential mass loss [2].
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Introduction Methodology Results Conclusions
Sheet Resistance Modeling, R(T,t,C)𝐿𝑛 (𝑅 )=𝛽0+𝛽1𝑇 +𝛽2𝑡+𝛽3𝐶+𝛽7𝑇𝑡𝐶 ,𝑇=[280−320 ] oC , 𝑡= [2 ,4 ] h𝑟𝑠 ,𝐶=[1 ,3 ]𝑚𝑔 /𝑚𝑙
0.33
-0.53
-0.26
-0.48
-0.24
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Introduction Methodology Results Conclusions
Sheet Resistance Modeling, R(T,t,C)• Verification? Center-point replicates, Residual plots
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Introduction Methodology Results Conclusions
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Introduction Methodology Results Conclusions
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Introduction Methodology Results Conclusions
Cyclic Bending
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Introduction Methodology Results Conclusions
Adhesion Test
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Introduction Methodology Results Conclusions
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G band
D band2D band
Introduction Methodology Results Conclusions
Raman Spectroscopy
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Introduction Methodology Results Conclusions
Supercapacitance Measurement
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Introduction Methodology Results Conclusions
Supercapacitance Measurement• Why it does not show a good capacitance behavior? EC decomposition Low surface area
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Introduction Methodology Results Conclusions
Conclusions and RecommendationsConclusions: • Graphene/EC powder Ink with adjusted viscosity No “coffee-
ring” effect
• Resistivity as low as + Complete statistical modeling for the thorough understanding of the electrical resistance behavior
• Mechanical tests Increase in annealing time will make the structure more brittle/weaker
• Not ideal capacitance behavior EC decomposition
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Introduction Methodology Results Conclusions
Conclusions and RecommendationsRecommendations:
• An automated and controlled coating technique for large industrial scales
• High yield and safe method for more graphene powder
• Thorough investigation of the interaction between graphene coating and the substrate.
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Thank you
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References
• [1] H. Chen, M. B. Müller, K. J. Gilmore, G. G. Wallace and D. Li, "Mechanically Strong, Electrically Conductive, and Biocompatible Graphene Paper," Adv Mater, vol. 20, pp. 3557-3561, 2008.
• [2] E. Jabari and E. Toyserkani, "Micro-scale aerosol-jet printing of graphene interconnects," Carbon, vol. 91, pp. 321-329, 9, 2015.
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Hierarchical Structures