Patterning of High-Viscosity Silver Paste by an Electrohydrodynamic-Jet Printer for Use in TFT Applications

Thi Thu Thuy Can,Tuan Canh Nguyen,Woon-Seop Choi

doi:10.1038/s41598-019-45504-5

Thi Thu Thuy Can, Tuan Canh Nguyen + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-45504-5

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Journal: Scientific Reports	Publication Date: Jun 24, 2019
Citations: 28	License type: open-access

Affiliation: Hoseo University

Abstract

Electrohydrodynamic (EHD) jet printing has a variety of benefits compared to conventional inkjet techniques, such as high resolution and the ability to work with high-viscosity pastes. In this work, Ag nanoparticles with 4000 cPs were chosen because they are printable on various substrates for electronic devices. The effects of additive on the high-viscosity Ag paste formulation were investigated, and pattern lines narrower than 100 μm were achieved by EHD-jet printing with an average sheet resistance of 0.027 Ω □−1. Furthermore, solution-processed oxide TFTs were fabricated with EHD jet-printed Ag electrodes for the first time. The electrical properties obtained were a current ratio of 1.5 × 106, a mobility of approximately 1 cm2 V−1 s−1, a threshold voltage of 21.5 V, and a subthreshold slope of 3.05 V dec−1.

Highlights

Electrohydrodynamic (EHD) jet printing is a technique with very potentials for directly patterning functional materials onto many substrates
Stabilizing and optimizing tip height is critical for microscale applications in EHD jet printing
The high viscosity of silver paste may be a problem with a majority of jet printing techniques

Summary

Introduction

Electrohydrodynamic (EHD) jet printing is a technique with very potentials for directly patterning functional materials onto many substrates. Some of our previous studies on EHD jet printing demonstrated high-resolution patterns compared to spin-coating and ink-jet techniques. The TFT characteristics attained using an EHD jet printer were much better than those obtained with spin-coating technology. An EHD jet-sprayed TFT showed a threshold voltage of 7.17 V and a very high on-to-off ratio of 107 12. An EHD jet-printed ZTO TFT showed a field-effect mobility of 9.82 cm[2] V−1 s−1, on-to-off current ratio of 3.7 × 106, and threshold voltage of 2.36 V at 500 °C13. A three-nozzle-EHD inkjet printing head was used to fabricate conductive lines of silver colloidal ink on glass substrate simultaneously. Silver line patterns from high-viscosity Ag paste formulations were produced using an EHD jet printer and applied in electronic devices.

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