2D-Crystal-Based Functional Inks

The possibility to produce and process graphene, related 2D crystals, and heterostructures in the liquid phase makes them promising materials for an ever‐growing class of applications as composite materials, sensors, in flexible optoelectronics, and energy storage and conversion. In particular, the ability to formulate functional inks with on‐demand rheological and morphological properties, i.e., lateral size and thickness of the dispersed 2D crystals, is a step forward toward the development of industrial‐scale, reliable, inexpensive printing/coating processes, a boost for the full exploitation of such nanomaterials. Here, the exfoliation strategies of graphite and other layered crystals are reviewed, along with the advances in the sorting of lateral size and thickness of the exfoliated sheets together with the formulation of functional inks and the current development of printing/coating processes of interest for the realization of 2D‐crystal‐based devices. An overview on the process chain of 2D crystals is provided from the exfoliation of layered bulk counterparts in liquid to yield nanosheets, with controlled lateral sizes and thicknesses, to ink formulation and their printing/coating processes on different substrates for the realization of printed devices.