Layered nanomaterial crystals with interesting electronic and optical properties are an attractive proposition for flexible photonic and optoelectronic devices. The most widely investigated layered material is graphene, which heralds the possibility of truly flexible and perhaps, transparent electronics. However, the lack of band gap in chemically pristine graphene sheets dictates their limited potential for electronics. Other graphene-like layered nanomaterials, in particular, semiconducting metal dichalcogenides offer bandgaps, and hence, the possibility of electronic devices with conventional architecture. Together, graphene and related layered materials thus represent a family of materials attractive for next generation flexible electronic components, devices and systems. For large area applications, growth of layered materials typically requires high temperature (～1000 °C). This is further complicated during their transfer deposition on to the target substrates. An alternative and economic approach is to use inks of exfoliated layers from their chemically untreated bulk crystals. This process can be carried out at room temperature and does not involve harsh chemicals. More importantly, the inks offer device fabrication and integration strategy through different processes, such as polymer composites, digital and lithographic printing as well as roll-to-roll (R2R) and spray coating over large area. I will discuss several photonic and (opto)electronic applications using graphene, the most established ink platform to date. This will include ultrafast lasers, transistors, hybrid nanomaterial transparent conductors and electrodes on silicon/glass, plastic and paper substrates. I will briefly address other layered material inks and their printability. I will conclude with a short perspective in terms of materials, printing technologies and devices that may evolve from this materials technology platform.
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