A Molecular Dynamics Simulation Study: The Inkjet Printing of Graphene Inks on Polyimide Substrates

Lingjun Wu ,Libo Gao,Wei Wang,Jibao Lu,Haitao Zhao,Rong Sun

doi:10.3389/fmats.2021.769071

Abstract

Inkjet printing-based 2D materials for flexible electronics have aroused much interest due to their highly low-cost customization and manufacturing resolution. However, there is a lack of investigation and essential understanding of the surface adhesion affected by the printing parameters at the atomic scale. Herein, we conducted a systematic molecular dynamics simulation investigating the inkjet printing of graphitic inks on polyimide substrates under various conditions. Simulations under different temperatures, inkjet velocities, and mechanical loadings such as pressure and deformation are performed. The results show that the best adhesion is achieved in the plasma-modified polyimide/graphene-oxide (mPI/GO) interfacial system (the interaction energy (Ein) between mPI and GO is ca. 1.2 times than with graphene). The adhesion strength decreases with increasing temperature, and higher inkjet velocities lead to both larger impact force as well as interfacial fluctuation, while the latter may result in greater interfacial instability. When loaded with pressure, the adhesion strength reaches a threshold without further improvement as continuing compacting of polymer slabs can hardly be achieved. The detachment of the interfaces was also explored and mPI/GO shows better resistance against delamination. Hopefully, our simulation study paves the way for future inkjet printing-based manufacturing of graphene-based flexible electronics.

Highlights

Flexible electronics are attracting increasing attention nowadays due to various superior properties over traditional rigid electronics
A systematic Molecular dynamics (MD) investigation focusing on graphitic ink/PI substrate inkjet printing has been conducted
MD results suggest the adhesion strength is follows: pristine graphene (PG)-modified PI (mPI)< PG-PI< graphene oxide (GO)-PI< GO-mPI, with the best adhesion strength achieved between mPI and GO, as it improved after introduction of hydrophilic groups through plasma treatment, which is consistent with the experimental results

Summary

Introduction

Flexible electronics are attracting increasing attention nowadays due to various superior properties over traditional rigid electronics. Organic and polymeric substrates are widely used in manufacturing, and in general, the potential producing cost is much lower To this day, flexible electronics is witnessed to have growing applications in various fields, such as sensors (Sekitani et al, 2009; Gao et al, 2019; Xu et al, 2020; Gao et al, 2021a; Gao et al, 2021b; Gao et al 2020; Huang et al, 2014; Lu et al, 2021; Li et al, 2021), electronic displays (Templier et al, 2007; Mizukami et al, 2018; Zhou et al, 2006; Han et al, 2012), solar cells (Granqvist 2007; Peng et al, 2017), nanogenerators (Liu et al, 2021), transistors (Chung et al, 2019), etc. Polyimides (PI) are one of the most widely polymeric flexible substrates used (Berggren et al, 2007; Lien et al, 2014; Song et al, 2017) due to their excellent flexibility and outstanding thermal stability (Tg:ca. 400°C), as well as being chemically inert under various conditions.

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Conclusion