Low temperature chemical sintering of inkjet-printed Zn nanoparticles for highly conductive flexible electronic components

Subimal Majee,Valerio Beni,David Nilsson,Pawel Jerzy Wojcik,Anurak Sawatdee,Mikael C. F. Karlsson,Peter Dyreklev,Mohammad Yusuf Mulla,Naveed ul Hassan Alvi

doi:10.1038/s41528-021-00111-1

Subimal Majee, Valerio Beni + Show 7 more

Open Access

https://doi.org/10.1038/s41528-021-00111-1

Copy DOI

Abstract

This study illustrates an innovative way to fabricate inkjet-printed tracks by sequential printing of Zn nanoparticle ink and curing ink for low temperature in situ chemical sintering. Employing chemical curing in place of standard sintering methods leads to the advantages of using flexible substrates that may not withstand the high thermal budgets of the standard methods. A general formulation engineering method is adopted to produce highly concentrated Zn ink which is cured by inkjet printing an over-layer of aqueous acetic acid which is the curing agent. The experimental results reveal that a narrow window of acid concentration of curing ink plays a crucial role in determining the electrical properties of the printed Zn nanoparticles. Highly conductive (~105 S m−1) and mechanically flexible printed Zn features are achieved. In addition, from systematic material characterization, we obtain an understanding of the curing mechanism. Finally, a touch sensor circuit is demonstrated involving all-Zn printed conductive tracks.

Highlights

Inkjet-printing of electrodes and connectors using conductive inks has captured much attention in the last couple of decades in various printed electronics applications owing to its noncontact[1,2], additive, and high-resolution drop-on-demand fabrication ability[3,4]
Formulating inkjet printable ink of nanomaterials is very challenging since inkjet printing requires the ink to have specific physical properties such as surface energy, viscosity, and density[24,25,26,27,28]
Inks must have a viscosity (η), surface tension (γ), and density (ρ) within suitable ranges for a fixed nozzle diameter (α). These parameters can be combined in a series of non-dimensional numbers: Reynolds number (Re) and Weber number (We), which are defined by Eqs. (1a) and (1b)[2,29,30]: Re 1⁄4 ðvραÞ=η

Summary

Introduction

Inkjet-printing of electrodes and connectors using conductive inks has captured much attention in the last couple of decades in various printed electronics applications owing to its noncontact[1,2], additive, and high-resolution drop-on-demand fabrication ability[3,4]. The overall costs of conductive tracks in the printed electronics applications may be decreased down up to 2 times of the current Ag NP-based tracks assuming the ink formulation process and other components (solvents, binders, and surfactants) remains nearly similar.

Results

Conclusion