Chemically Engineered Substrates for Patternable Growth of Two-Dimensional Chalcogenide Crystals.

Abstract

The key challenge of direct integration of two-dimensional (2D) chalcogenide crystals into functional modules is precise control of the nucleation sites of the building blocks. Herein, we exploit the chemical activities and surface engineering of the substrates to manipulate the nucleation energy barrier of 2D crystals and thereby realize the patternable growth of 2D crystals. The selective-region chemical modifications of the substrates are achieved via microcontact printing combined with the elegant self-assembly of octadecyltrichlorosilane molecules on the substrates. The patternable growth method is versatile and can be used as a general strategy for growing a broad class of high-quality 2D chalcogenide crystals with tailorable configurations on a variety of chemically engineered substrates. Moreover, we demonstrate flexible transparent electrodes based on large-scale patterned nanogrids of topological insulator Bi2Se3, which possess tailored trade-off between electric conductivity and optical transmittance across the visible to near-infrared regime. We hope this method may open an avenue to the efficient integration and batch production of 2D chalcogenide crystals and could inspire ongoing efforts of the fabrication of van der Waals heterostructures.