Nanoengineering of multicomponent reversible graphene superlattices: Probing the fundamentals from the molecular level to the device scale.

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The nanoarchitecture of 2D materials is of great interest in the scientific community and is recently exploited widely to tailor its electrical, chemical, optical, and mechanical properties. Chemical and photochemical reactions are the two promising methods to anchor the functional groups on 2D materials, in which the former reaction induces large-scale modification while the latter introduces spatially localized defects (sub-micron precision). Indeed, the precise control over the covalent functionalization of 2D materials at the molecular level still remains a challenging task due to the lack of molecular identity, spatial distribution, and density at the molecular level. In this proposal, a novel multicomponent reversible graphene superlattice consisting of both covalent and non-covalent bound moieties will be constructed with the aid of nano spectroscopy techniques such as TERS and nanoIR. The customized modulation of electrical and optical properties of the superlattice by exploiting the molecular switching events through external stimuli will enable the fabrication of multifunctional graphene substrates. The nano-spectroscopy techniques together with state-of-the-art surface analyzing techniques (AFM, STM, KPFM) permit real-time nanoscale chemical mapping and molecular visualization on the graphene layer. Furthermore, the synergy between STM/AFM imaging and time-resolved optical spectroscopy will be employed in this project in order to resolve the real-time ensembled dynamics of photoisomerization and the associated self-assembly of the photochromic molecules on the graphene layer. The sub-nanoscale molecular information will facilitate precise Fermi-level engineering. Finally, the feasibility of devising new flexible and transparent field-effect transistors (FET) devices using the newly architect graphene superlattices will be scrutinized.