High-yield exfoliation of 2D semiconductor monolayers and reassembly of organic/inorganic artificial superlattices

The scalable preparation of high-purity monolayers is essential for practically integrating two-dimensional (2D) semiconductors in diverse technologies but remains a persistent challenge. Previous efforts to exfoliate 2D layered crystals by the organic ammonium intercalation usually produce few-layer nanosheets owing to a self-retarding effect that hinders the complete intercalation in neighboring layers. Herein, we report a unique intercalation and separation'' chemistry with a constant self-refreshing crystal surface that mitigates the self-retarding effect to ensure a complete intercalation of the bulk crystal, ultimately enabling high-yield solution-phase exfoliation of 2D semiconductor monolayers in excellent purity (e.g., monolayer purity of >95% for In2Se3 and InSe). Furthermore, we have assembled large-area organic/inorganic hybrid superlattices with diverse organic molecules and inorganic 2D monolayer crystals, thus creating a family of artificial superlattice materials with atomically modulated chemical compositions, widely tunable superlattice periodicities, and specifically tailorable electronic and thermal properties.

Automated summary

A unique intercalation and separation chemistry has been proposed to successfully overcome the self-retarding effect and achieve complete intercalation of bulk crystals. This method enables high-yield preparation of highly pure 2D semiconductor monolayers and the assembly of large-area organic/inorganic hybrid superlattices, creating a new field of artificial superlattice materials.