# Chemical Control of Mechanical Anisotropy and Band Alignment in Perylene-based Two-dimensional MoS$_2$-Organic Hybrids

## TL;DR

This paper investigates how chemical modifications of organic molecules can control the mechanical anisotropy and electronic band alignment in MoS₂-organic hybrid materials, revealing tunable properties for potential applications.

## Contribution

It demonstrates the ability to tailor mechanical and electronic properties of MoS₂ hybrids through chemical modifications of attached organic molecules using density functional theory.

## Key findings

- Distinct differences in properties due to chemical composition and geometry.
- PO exhibits the greatest mechanical anisotropy.
- Organic molecules alter band alignment and work function.

## Abstract

This study presents a comprehensive investigation of hybrid interfaces formed by monolayer MoS$_2$ coupled with the organic molecules perylene (P), perylene diimide (PDI), and perylene orange (PO). Using density functional theory, we demonstrate the extent to which the mechanical and electronic properties of a hybrid system can be altered by the chemical modification of a given chromophore. The three systems exhibit distinct differences due to their chemical composition and van der Waals contact enabled by their geometry. All systems are structurally stable. The binding energies follow the order PD$>$P$>$PO due to the large $\pi$-system (PD) and strong structural distortion (PO). Young's modulus and Poisson's ratio exhibit pronounced anisotropy in all cases. PO exhibits the greatest anisotropy due to steric effects and a permanent dipole, which introduce directionality to the molecule-surface interaction. Physisorption is accompanied by net charge transfer in the same order as the binding energies. The associated interfacial polarization results in a change in the work function compared to pristine MoS$_2$ in the order P$>$PO$>$PD. Finally, the presence of organic molecules introduces states into the MoS$_2$ energy gap, with the band alignment being either type II (P, PO) or type I (PD).