Moir\'e lattice of twisted bilayer graphene as template for non-covalent functionalization

TL;DR

This paper demonstrates how the moiré lattice pattern of twisted bilayer graphene can be used as a template to control non-covalent functionalization, enabling nanoscale patterning of 2D materials based on twist angle variations.

Contribution

It introduces a novel method to spatially control non-covalent functionalization of tBLG using its moiré pattern, supported by experimental and theoretical evidence.

Findings

Functionalization degree varies with twist angle.

HATCN molecules preferentially attach to AB-stacked regions.

Moiré pattern guides non-covalent functionalization.

Abstract

We present a novel approach to achieve spatial variations in the degree of non-covalent functionalization of twisted bilayer graphene (tBLG). The tBLG with twist angles varying between ~ 5{\deg} and 7{\deg} was non-covalently functionalized with 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) molecules. Our results show a correlation between the degree of functionalization and the twist angle of tBLG. This correlation was determined through Raman spectroscopy, where areas with larger twist angles exhibited a lower HATCN peak intensity compared to areas with smaller twist angles. We suggest that the HATCN adsorption follows the moir\'e pattern of tBLG by avoiding AA-stacked areas and attach predominantly to areas with a local AB-stacking order of tBLG, forming an overall ABA-stacking configuration. This is supported by density functional theory (DFT) calculations. Our work highlights the role of the moir\'e lattice in controlling the non-covalent functionalization of tBLG. Our approach can be generalized for designing nanoscale patterns on two-dimensional (2D) materials using moir\'e structures as a template.