With the increasing importance of portable and wearable electronic technologies, new materials are needed that combine superlative electronic properties with other requirements such as mechanical flexibility, low power consumption, and scalable manufacturing. Emerging two-dimensional nanoelectronic materials that are atomically thin meet many of these requirements, but no single material can achieve all of them concurrently. Consequently, this project develops heterostructures that synergistically integrate the desirable properties of multiple two-dimensional nanoelectronic materials, thus overcoming the design tradeoffs imposed by single materials utilized in isolation. Solution-processing methods are further employed to achieve highly homogenous nanoelectronic heterostructures in a manner that is compatible with large-scale, low-cost additive manufacturing. The results of this project are disseminated through a comprehensive set of education and outreach activities that include graduate curriculum development, undergraduate laboratories, and a materials science exhibit at the Chicago Museum of Science and Industry.
To realize reproducibly high performance in electronic and optoelectronic devices, nanoelectronic materials must be produced via scalable methods that possess high structural monodispersity. Furthermore, the resulting nanoelectronic material components need to be assembled into morphologies that preserve their superior properties and are amenable to subsequent fabrication methods. Towards these goals, dispersion chemistries, solvents, and density gradient media are identified that enable density gradient ultracentrifugation sorting of transition metal dichalcogenides, boron nitride, and black phosphorus with exceptional structural and electronic purities. These high purity samples facilitate fundamental studies of two-dimensional nanoelectronic materials as a function of structural parameters such as thickness and lateral size. In addition, homogeneous two-dimensional nanomaterial dispersions are assembled via vacuum filtration and layer-by-layer assembly to form multi-component bulk heterojunction nanocomposite films and thin-film heterostructures that are suitable for the fabrication and testing of large-area nanoelectronic devices and circuits. In this manner, the role of surface and interfacial chemistry on electronic properties are elucidated at the two-dimensional limit.
