Selective multi-nanosoldering for fabrication of advanced solution-processed micro/nanoscale metal grid structures

Y S Oh,K Kang,H Lee,I Park,D Y Choi,H J Sung,J Lee,S Yoo

doi:10.1038/s41598-020-63695-0

Y S Oh, K Kang + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-63695-0

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Abstract

Solution-processed metal grid transparent conductors with low sheet resistance, high optical transmittance and good mechanical flexibility have great potential for use in flexible optoelectronic devices. However, there are still remaining challenges to improve optoelectrical properties and electromechanical stability of the metallic structures due to random loose packings of nanoparticles and the existence of many pores. Here we introduce a selective multi-nanosoldering method to generate robust metallic layers on the thin metal grid structures (< a thickness of 200 nm), which are generated via self-pining assisted direct inking of silver ions. The selective multi-nanosoldering leads to lowering the sheet resistance of the metal grid transparent conductors, while keeping the optical transmittance constant. Also, it reinforces the electromechanical stability of flexible metal grid transparent conductors against a small bending radius or a repeated loading. Finally, organic light-emitting diodes based on the flexible metal grid transparent conductors are demonstrated. Our approach can open a new route to enhance the functionality of metallic structures fabricated using a variety of solution-processed metal patterning methods for next-generation optoelectronic and micro/nanoelectronic applications.

Highlights

Solution-processed metal grid transparent conductors with low sheet resistance, high optical transmittance and good mechanical flexibility have great potential for use in flexible optoelectronic devices
The metal grid structures were fabricated on a glass substrate via self-pinning assisted direct inking of silver ions
After the mold was detached, the meniscus of the grid-patterned ink was kept pinned at contact lines due to the spreading inhibition induced by the confinement of the silver NPs and organic complexes[29]

Summary

Introduction

Solution-processed metal grid transparent conductors with low sheet resistance, high optical transmittance and good mechanical flexibility have great potential for use in flexible optoelectronic devices. The unsintered metal grid structures with non-uniform shape and thickness (> μm) suffered from a local damage or a crack generation, resulting in locally unstable mechanical, electrical and optical properties during the mold detachment These issues hindered the use of large-scale TCs. Recently, solution-grown (SG) metal grid TCs fabricated using electroless plating or electroplating have been reported to show excellent optoelectrical properties. We introduce a selective multi-nanosoldering (SMN) method for simultaneously enhancing both optoelectrical properties and electromechanical stability of solution-processed metal grid structures without polymer masks and etching process. The effect of SMN on the electromechanical stability of flexible metal grid TCs after a transfer process was examined under static and dynamic bending stresses

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