16 - Electronic devices based on solution-processed two-dimensional materials

Abstract

Owing to the unique characteristics such as electron mobility, large surface area, mechanical robustness, and so on, two-dimensional (2D) materials have vast potential for the applications in electronic devices. However, many of the demonstrated devices are based on mechanically exfoliated 2D materials that limit their wider applications. In fact, one attribute that makes the 2D materials stand out is their large reserve on Earth, for example, graphite. This allows the scale-up application of some 2D materials at a reasonable cost. At present, the common solution-based methods include liquid-phase exfoliation using sonication or high shear force, electrochemical exfoliation, and intercalation using ions to overcome the interlayer van der Waals force and expand the layers. Also 2D materials can be functionalized with oxygen functional groups, for example, graphene oxide, and on this basis even other functional groups as well. Those preparation methods provide a large diversity of 2D material–based solutions/inks in different solvents that can be customized for specific applications. With the 2D material–based solutions, various fabrication methods have been developed such as coating, filtration, electrophoretic deposition, and most recently three-dimensional printing. These methods have their own requirements in terms of the solvent, viscosity, concentration, and the choice of appropriate instruments as well. As a consequence, it provides choices for a range of industrial and scientific applications, covering electrical/thermal conductors, energy storage devices, sensors, optoelectronics, photonics and transistors, and so on. In this chapter the preparation of 2D materials in solution, device fabrication as well as their applications is summarized, including their pros and cons, so as to give the readers a brief idea about the big picture of device fabrication based on solution-processed 2D materials.