Control and characterization of the preferential crystalline orientation of MoS2 2D flakes in printed layers

TL;DR

This paper investigates how different printing methods affect the crystalline orientation of MoS2 2D flakes in printed layers, using XRD analysis to identify optimal deposition techniques for device fabrication.

Contribution

It demonstrates that the choice of printing method drastically influences the crystalline orientation of MoS2 flakes, with spin-coating producing the most favorable basal fiber texture.

Findings

Spin-coating yields the best basal fiber texture.

Crystalline orientation depends on the printing method used.

XRD pole figure analysis effectively characterizes orientation.

Abstract

The recent development of Liquid Phase Exfoliation (LPE) of 2D materials has enabled the formulation of inks with rheological properties adapted to numerous liquid deposition methods. This has allowed the fabrication of various types of printed devices with unique features stemming from the nano-structure of the printed 2D layers. In this short communication, we demonstrate that the preferred crystalline orientation of printed MoS2 flakes depends drastically upon the printing method employed to deposit the layers. Using angle resolved X-Ray Diffraction (XRD) to measure Pole Figure and subsequently calculate Orientation Distribution Functions (ODF), we show that the spin-coating method yields the best basal fiber texture, most likely because of the shear force at work on the flakes during the deposition process. This interim report thereby paves the way to further investigations and fine control of the preferred crystalline orientation of printed 2D flakes for the development of dedicated devices.