Screen-Printed Structures from a Highly Conductive Mildly Oxidized Graphene Suspension for Flexible Electronics

Area of Science:

• Materials Science
• Nanotechnology
• Electronics Engineering

Background:

• Graphene's unique properties are attractive for flexible electronics.
• Developing cost-effective and scalable methods for graphene-based device fabrication is crucial.

Purpose of the Study:

• To synthesize mildly oxidized graphene (MOG) suspension.
• To fabricate flexible humidity sensors and supercapacitors using screen-printed MOG films.
• To investigate the effect of reduction methods on MOG film properties.

Main Methods:

• Electrochemical exfoliation of natural graphite to produce MOG suspension (~20% atomic oxygen).
• Screen printing of MOG films (5 μm thickness) onto flexible substrates.
• Thermal (200 °C) and laser (474 nm, 200 mW) reduction of MOG films.

Main Results:

• Screen-printed MOG films achieved surface resistance of 10^2-10^3 kΩ/sq, reduced to 1.5 kΩ/sq (thermal) and ~0.065 kΩ/sq (laser).
• Fabricated flexible supercapacitors exhibited specific capacitance of ~6 μF/cm^2, with a 40% capacitance drop at a 2 mm bending radius.
• Developed humidity sensing structures with 9% sensitivity.

Conclusions:

• Screen printing of MOG is a viable technique for fabricating flexible electronic components.
• Reduction methods significantly improve the electrical conductivity of MOG films.
• The developed MOG-based devices show potential for flexible sensing and energy storage applications.