A General Method for Synthesizing van der Waals and Non-van der Waals Moiré Superlattices from Molecular Crystals

Quantum materials have received a lot of interest in recent years because of their unusual and remarkable properties. Angular stacking of two-dimensional (2D) nanoscale crystalline sheets into interacting superstructures, such as moiré superlattices, can result in unique physical and chemical properties solely through interlayer interactions. Moiré superlattices are generally formed from 2D van der Waals (vdW) materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDCs). These superlattices are fabricated using mechanical positioning of the constituent lattices; however, their scalable fabrication is challenging. Further, current interests in the field demands the development of a generalized approach for high-quality and scalable moiré superlattice fabrications. Chemistry-based methods in the liquid media may be helpful in this regard. Here, we report the development of a generalized method for synthesising moiré superlattices from covalent molecular crystals, ionic crystals, and metal complex crystals, which consist of finely grounding bulk crystals and sonicating the grounded crystals in an ultrasonic bath at moderate temperature in the presence of a solvent system to obtain a dispersion of the superlattices. This discovery opens up new options for designing and fabricating moiré superlattices from various materials and for studying the chemistry of nanoscale 2D moiré materials.