Role of substrate surface morphology on the performance of graphene inks for flexible electronics

TL;DR

This study explores how substrate surface morphology influences the uniformity and electrical performance of graphene inks on flexible paper substrates, demonstrating improved film quality and device functionality through surface engineering.

Contribution

It introduces the role of surface morphology in optimizing graphene ink deposition on paper, enabling high-performance flexible electronic devices without additional treatments.

Findings

Good wetting surfaces produce uniform, low-resistance films

Surface morphology control improves device performance

THz-TDS effectively evaluates ink uniformity and conductivity

Abstract

Two-dimensional (2D) materials, such as graphene, are seen as potential candidates for fabricating electronic devices and circuits on flexible substrates. Inks or dispersions of 2D materials can be deposited on flexible substrates by large-scale coating techniques, such as inkjet printing and spray coating. One of the main issues in coating processes is nonuniform deposition of inks, which may lead to large variations of properties across the substrates. Here, we investigate the role of surface morphology on the performance of graphene ink deposited on different paper substrates with specific top coatings. Substrates with good wetting properties result in reproducible thin films and electrical properties with low sheet resistance. The correct choice of surface morphology enables high-performance films without postdeposition annealing or treatment. Scanning terahertz time-domain spectroscopy (THz-TDS) is introduced to evaluate both the uniformity and the local conductivity of graphene inks on paper. A paper-based strain gauge is demonstrated and a variable resistor acts as an on-off switch for operating an LED. Customized surfaces can thus help in unleashing the full potential of ink-based 2D materials.