Inkjet printing of high-concentration particle-free platinum inks

Timothy D Grant,Andrew C Hourd,Svetlana Zolotovskaya,John B Lowe,Rosemary J Rothwell,Thomas D.A Jones,Amin Abdolvand

doi:10.1016/j.matdes.2021.110377

Timothy D Grant, Andrew C Hourd + Show 5 more

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https://doi.org/10.1016/j.matdes.2021.110377

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Journal: Materials & Design	Publication Date: Dec 31, 2021
Citations: 5	License type: cc-by

Affiliation: University of Dundee

Abstract

An investigation into the optimisation of a highly-concentrated (20 wt%) and stable platinum (Pt) organometallic ink, showing consistent jetting performance whilst minimising the negatives associated with particle-containing inks. The ink was synthesised and printing demonstrated onto glass by a piezoelectric drop-on-demand inkjet printer. Stable and rapid jetting (Z number: 1.83, 8 m/s) was achieved using cyclohexanol-based viscosity modifiers and optimisation of the print settings. Uniform nanofilms (10 – 30 nm) were obtained by the printing of successive layers which showed high conductivities (1.6 ± 0.13 × 106S/m, 17% of bulk Pt). The 20 wt% concentrated inks showed increased uniformity and electrical conductivity over previously reported 10 wt% equivalent inks, enabling for the first-time conductive features with a single print pass. High quality films were deposited by increasing the printed thickness due to significant uniformity improvements obtained across the centre of the printed films. A high film purity was demonstrated by X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-rays. The suitability of the printed Pt films for production of Surface Enhanced Raman Scattering (SERS) detection platforms was also investigated. The presented work will pave the way for applications benefiting from selective deposition and low reactivity Pt nanofilms, as a proof of concept an LED circuit is demonstrated.

Highlights

Inkjet printing offers a non-contact, lower capital expenditure alternative fabrication technique to traditional lithographic pro-⇑ Corresponding author.cesses, with near zero waste [1] and is an adaptable and accessible additive manufacturing process with applications for the direct patterning of conductive features [2]
The density, dynamic viscosity and surface tension were measured for each blank ink solution as outlined within Table 2, enabling evaluation of the inverse Ohnesorge number (Z) of each
Fluids with Z numbers towards the lower recommended range generally suffer from high dynamic viscosities that prevent drop ejection, high Z values indicate the formation of large numbers of unwanted satellites along with the primary droplet [22]

Summary

Introduction

Inkjet printing offers a non-contact, lower capital expenditure alternative fabrication technique to traditional lithographic pro-⇑ Corresponding author.cesses, with near zero waste [1] and is an adaptable and accessible additive manufacturing process with applications for the direct patterning of conductive features [2]. Printed electronic devices by inkjet method have great potential in manufacturing processes requiring rapid production without otherwise bespoke or expensive equipment [3], such as prototyping, whilst reducing waste. Of interest is platinum (Pt) which is a highly stable, conductive and inert noble metal that is readily available in a highly pure form [4]. These characteristics lend Pt to a wide range of applications in small quantities in electronic devices such as hard disks [5], resistance thermometers [6] and electrodes on medical implants [7]. Existing research with particle-based Pt inks has demonstrated applications as electrodes for fuel cells [8] and pH sensors [9]

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