Effect of Carboxylic Acid on Sintering of Inkjet-Printed Copper Nanoparticulate Films

Woo, Kyoohee; Kim, Youngwoo; Lee, Byungyoon; Lee, Jong Hyun; Moon, Jooho

doi:10.1021/am2002907

Cited by 112 publications

(93 citation statements)

References 19 publications

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“…26 The chemical transformation into phase-pure Cu nanowires through a simple wet treatment facilitated the fabrication of highly conductive Cu nanomaterials at room temperature without the incorporation of toxic chemical environments, unlike the previously reported methods. 27,28 Notably, for AgNWs prepared using sophisticated procedure, an annealing process at slightly elevated temperatures ranging from 80 − 220°C is highly recommended for inducing nano-welding between neighboring nanowires owing to the presence of organic capping molecules. In some cases, this can limit the integration of thermally vulnerable functional moieties.…”

Section: Resultsmentioning

confidence: 99%

A highly stretchable, helical copper nanowire conductor exhibiting a stretchability of 700%

et al. 2014

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Recent advances in unconventional foldable and stretchable electronics have forged a new field in electronics. However, traditional conducting metal oxides and metal thin films are inappropriate as electrodes for stretchable devices because they are vulnerable to tensile strain as well as bending strain. In this study, we describe the fabrication of annealing-free, copper nanowire (CuNW)-based stretchable electrodes using an inexpensive metal source through a simple and scalable process at low temperature without a vacuum. We also introduce a reversible and extremely stretchable (up to 700% of strain) helical, CuNW-based conducting spring, which has not been previously used for stretchable electrodes. NPG Asia Materials (2014) 6, e132; doi:10.1038/am.2014.88; published online 26 September 2014 INTRODUCTION Recent advances in unconventional foldable and stretchable electronics show great potential for future wearable applications, including smart skins, electronic eye-type imagers, skin-like pressure sensors, electronic textiles and muscle-like soft actuators. 1-5 Most of these applications require sufficient elasticity for bending, stretching, twisting and deformation into complex, non-planar shapes while maintaining good electrical properties and reliability. Stretchability is the most crucial property for the development of next-generation wearable devices. To date, two primary strategies have been suggested for the fabrication of stretchable electronic parts apart from complex lithography-based approaches that can shape inorganic conductive materials or metals into buckled geometries, including island-bridge systems. [6][7][8][9] The first strategy is the inclusion of micro-or nano-scale conductive carbon materials into elastic polymer matrices. 1,10-13 For example, carbon-based materials, such as carbon nanotubes and graphene, have been extensively researched for stretchable/foldable conductors. Ma et al. 13 fabricated helical ribbon-structured composites composed of carbon nanotubes and Ag flakes using a shape-memory polymer, demonstrating stable resistivity up to a strain of 600%. However, the application of these materials in large-area, integrated devices may be restricted by their relatively poor electrical properties and their high cost. The second strategy is to use highly conductive metallic nanostructures, such as rectangular-patterned gold nanosheets 14 (strain (ε) = 100% on Ecoflex substrate) or silver nanoparticles embedded in composite materials 15 (ε = 140% on elastomeric rubber fiber).Recently, networks of one-dimensional metal nanowires, accompanied by a simple, scalable process (for example, solution-phase

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Section: Resultsmentioning

confidence: 99%

A highly stretchable, helical copper nanowire conductor exhibiting a stretchability of 700%

et al. 2014

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“…It has been reported that the lactic acid can react with copper oxide/ hydroxide to form an organic copper salt, which is subsequently reduced into elemental copper at elevated temperatures under a protective atmosphere. 24,25 Therefore, as long as the resulting organic copper salt is soluble in a given solvent, lactic acid would be an effective chemical remover for both surface oxide/hydroxide. Lactic acid treatment leads to the formation of copper lactate as a result of the reaction with the copper oxide/hydroxide, as follows:…”

Section: Annealing-free Fabrication Y Won Et Almentioning

confidence: 99%

Annealing-free fabrication of highly oxidation-resistive copper nanowire composite conductors for photovoltaics

et al. 2014

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Copper nanowire (CuNW)-network film is a promising alternative to the conventional indium tin oxide (ITO) as a transparent conductor. However, thermal instability and the ease of oxidation hinder the practical applications of CuNW films. We present oxidation-resistive CuNW-based composite electrodes that are highly transparent, conductive and flexible. Lactic acid treatment effectively removes both the organic capping molecule and the surface oxide/hydroxide from the CuNWs, allowing direct contact between the nanowires. This chemical approach enables the fabrication of transparent electrodes with excellent properties (19.8 X sq À1 and 88.7% at 550 nm) at room temperature without any atmospheric control. Furthermore, the embedded structure of CuNWs with Al-doped ZnO (AZO) dramatically improves the thermal stability and oxidation resistance of CuNWs. These AZO/CuNW/AZO composite electrodes exhibit high transparency (83.9% at 550 nm) and low sheet resistance (35.9 X sq À1 ), maintaining these properties even with a bending number of 1280 under a bending radius of 2.5 mm. When implemented in a Cu(In 1 Àx ,Gax)(S,Se) 2 thin-film solar cell, this composite electrode demonstrated substantial potential as a low-cost (Ag-, In-free), high performance transparent electrode, comparable to a conventional sputtered ITO-based solar cell. NPG Asia Materials (2014) 6, e105; doi:10.1038/am.2014.36; published online 13 June 2014Keywords: chemical reduction treatment; copper nanowire; indium-free transparent electrodes; photovoltaic; thermal oxidation resistance INTRODUCTION Transparent conductive materials are a crucial, basic element in the realization of various optoelectronic devices, such as flat panel displays, touch screens, organic light emitting diodes and thin-film solar cells. 1-3 Indium tin oxide (ITO) has been the most widely explored material, because of its excellent transparency (B90% at 550 nm) and low sheet resistance (B20 O sq À1 ). However, with the rising demand for transparent electrodes, the development of cost-effective alternatives to ITO has been of great importance. The quest for alternative transparent conductors, including conducting polymers, carbon nanotubes, graphenes and nanostructured electrodes, has been a topic of active research for the last decade. 4 Among these materials, metal-nanowire network films are thought to be a substantial candidate. The metallic nanowire film is capable of providing high transparency and conductivity by virtue of its characteristic structure, which consists of a percolated random network of nanowires. [5][6][7][8][9] Unlike the brittle metal oxide skeletonbased ITO, metal-nanowire films are easily applicable to bendable, wearable active devices, because of the inherently flexible nature of metals. A high aspect ratio is a critical factor for high transparency and conductivity, but metal nanowires possessing this quality suffer

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“…The problem is that an actual bonding surface consists of an oxide film and a machined layer; [3][4][5][6][7] therefore, adhesion between surfaces at the bond interface and removal of the oxide film represent necessary requirements to obtain high bond strength. Recently, ultrasonic vibration, [8][9][10][11][12][13] plasma processing, [14][15][16][17][18][19] and organic acid pretreatment [20][21][22][23] have been investigated as methods for breaking and cleaning a superficial oxide film. Indeed, in a previous study, we showed that modification of an oxide film with formic acid greatly improves the strength of bonding between tin surfaces 22) and between tin and copper.…”

Section: Introductionmentioning

confidence: 99%

Cu/Cu direct bonding by metal salt generation bonding technique with organic acid and persistence of reformed layer

Koyama

Hagiwara

Shohji

2015

Jpn. J. Appl. Phys.

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In this study, the effect of the metal salt generation bonding technique on the strength of a direct-bonded copper–copper interface was investigated. Copper surfaces were modified by boiling in several types of organic acids, and direct bonding was performed at a bonding temperature of 423–673 K under a load of 588 N (for a bonding time of 0.9 ks). As a result of the surface modification, bonded joints were obtained at bonding temperatures of 150 K (after treatment with formic acid) and 100 K (after citric acid treatment) lower than that required for the unmodified surfaces. In addition, the duration of the modification effects was investigated by exposing the modified surface to an air atmosphere furnace kept at 323 K. The bonding strength of the citric acid-modified surface remained unchanged even after 168 h, whereas that of the surface modified with formic acid decreased within 6 h.

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Effect of Carboxylic Acid on Sintering of Inkjet-Printed Copper Nanoparticulate Films

Cited by 112 publications

References 19 publications

A highly stretchable, helical copper nanowire conductor exhibiting a stretchability of 700%

A highly stretchable, helical copper nanowire conductor exhibiting a stretchability of 700%

Annealing-free fabrication of highly oxidation-resistive copper nanowire composite conductors for photovoltaics

Cu/Cu direct bonding by metal salt generation bonding technique with organic acid and persistence of reformed layer

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