Abstract
In this study, the screen-printed flexible humidity sensor and supercapacitor structures from a suspension of mildly oxidized graphene (MOG) was obtained. MOG suspension with a low atomic oxygen content (~20%) was synthesized by electrochemical exfoliation of natural graphite in an aqueous solution of ammonium sulfate. MOG films (average thickness 5 μm) with a surface resistance of 102–103 kΩ/sq were obtained by screen printing on a flexible substrate. The thermal reduction of MOG films at 200 °C reduced the surface resistance to 1.5 kΩ/sq. The laser reduction with a 474 nm and 200 mW solid-state laser reduced the surface resistance to ~0.065 kΩ/sq. Various structures were screen-printed on a flexible substrate for a variety of flexible electronics applications. The structures representing a flat supercapacitor had an average specific capacitance of ~6 μF/cm2. The tensile deformations occurring during bending reduced the capacitance by 40% at a bending radius of 2 mm. Humidity sensing structures with sensitivity of 9% were obtained.
Highlights
The development of technologies for producing new two-dimensional (2D) materials and their application in the field of flexible electronics is an important scientific and practical task
We investigated the effect of the speed of movement of a laser beam over a surface on a decrease in the surface resistance of mildly oxidized graphene (MOG) films
Humidity sensors and supercapacitors were obtained by screen printing of MOG suspension on a flexible Polyethylene terephthalate (PET) substrate
Summary
The development of technologies for producing new two-dimensional (2D) materials and their application in the field of flexible electronics is an important scientific and practical task. The use of graphene-based materials in printed electronics allows obtaining flexible electronic circuits, various sensors, supercapacitors, etc. Due to the presence of diverse functional groups, graphene oxide (GO) can be used as a base material for various sensors. Thermal annealing at high temperatures of 300–450 ◦C is the most commonly used method for strong reduction of GO. Such temperatures cause thermal degradation of most types of flexible polymer substrates at [10]. The development of technological methods for creating electronic structures from rGO on the surface of flexible polymer substrates with high conductivity is an important task
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