Screen printing of silver nanowires: balancing conductivity with transparency while maintaining flexibility and stretchability

Weiwei Li,Shuai Yang,Atif Shamim

doi:10.1038/s41528-019-0057-1

Weiwei Li, Shuai Yang + Show 1 more

Open Access

https://doi.org/10.1038/s41528-019-0057-1

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Abstract

Printing metal nanowires are particularly attractive as compared to conventional coating methods due to the ease of processing, direct patterning, and large-scale fabrication capability. However, it is still challenging to print metal nanowire patterns that simultaneously have high conductivity, high transparency, flexibility, and stretchability. Three steps have been taken in this work to balance the transparency and conductivity of the screen-printed flexible and stretchable silver nanowire films, (1) selection of the ink formulation, (2) optimization of the printing parameters, and (3) posttreatment with a laser. The as-obtained silver nanowire patterns are large-area and demonstrate an ultralow sheet resistance of 1.9 ohm/sq, high transmittance (73%) at the wavelength of 550 nm, and an ultrahigh figure of merit (~136) as compared to the printed silver nanowire electrodes in the literature. The screen-printed transparent patterns exhibit excellent electrical stability and mechanical repeatability when subjected to 1000 bending cycles with a bending radius of 28 mm and 1000 stretch-release cycles with 10% strain, which makes the transparent patterns suitable for the fabrication of flexible, transparent microwave absorbers. The absorption performance of the prepared frequency selective surface absorbers indicates no obvious degradation after various manipulating configurations and multiple bending and stretching cycles. The results are promising enough to make this ink and screen-printing process suitable for many applications of flexible, stretchable, and transparent electronics.

Highlights

Flexible and stretchable devices have become crucial for relatively new applications such as flexible sensors and actuators,[1,2,3] electronic textiles,[4,5,6] deformable displays,[7] and electromagnetic structures.[8,9] It is essential in these fields to develop electrodes that can offer decent conductive properties despite enduring multimodal and repeated deformations.[10]
We demonstrate a new kind of Ag NW ink for screen printing to deposit transparent Ag NW patterns on elastic poly(dimethyl siloxane) (PDMS) substrates and optimize the Ag loading, the printing parameters, and the posttreatment with laser to balance the transparency and conductivity, while maintaining the flexibility and stretchability (Fig. 1b)
The Ag NWs for the screen-printing ink were synthesized by reducing Ag nitrate in the presence of polyvinyl pyrrolidone (PVP) in ethylene glycol (EG)

Summary

Introduction

Flexible and stretchable devices have become crucial for relatively new applications such as flexible sensors and actuators,[1,2,3] electronic textiles,[4,5,6] deformable displays,[7] and electromagnetic structures.[8,9] It is essential in these fields to develop electrodes that can offer decent conductive properties despite enduring multimodal and repeated deformations.[10]. Advances in this context have led to the development of many nanomaterials, including nanowires (NWs),[12,13] nanotubes,[14,15,16,17,18] and graphene.[19,20,21,22,23] Among these building blocks, silver nanowires (Ag NWs) have attracted extensive attention in the last decade because of the excellent mechanical compliance, such as stretchability and flexibility, which is essential for wearable electrodes.[3,13,24,25] many filmlike electrodes made of Ag NWs are capable of achieving both high optical transparency and high electrical conductivity, two critical parameters for many optoelectronic devices, including liquid crystal displays, light emitting diodes (LEDs), solar cells, and touch panels.[13,26,27,28,29]

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