Jun Ran

Flexible transparent conductive films combining flexographic printed silver grids with CNT coating

A high-performance ITO-free transparent conductive film (TCF) has been made by combining high resolution Ag grids with a carbon nanotube (CNT) coating. Ag grids printed with flexography have a 20 μm line width at a grid interval of 400 μm. The Ag grid/CNT hybrid film exhibits excellent overall performance, with a typical sheet resistance of 14.8 Ω/□ and 82.6% light transmittance at room temperature. This means a 23.98% reduction in sheet resistance and only 2.52% loss in transmittance compared to a pure Ag grid film. Analysis indicates that filling areas between the Ag grids and interconnecting the silver nanoparticles with the CNT coating are the primary reasons for the significantly improved conductivity of the hybrid film that also exhibits excellent flexibility and mechanical strength compared to an ITO film. The hybrid film may fully satisfy the requirements of different applications, e.g. use as the anode of polymer solar cells (PSCs). The J-V curve shows that the power conversion efficiency (PCE) of the PSCs using the Ag grid/CNT hybrid anode is 0.61%, which is 24.5% higher than that of the pure Ag grids with a PCE of 0.49%. Further investigations to improve the performance of the solar cells based on the printed hybrid TCFs are ongoing.

A Nano-Silver Inkjet Conductive Ink with Excellent Adhesion

In this paper，the preparation of a solvent based nano-silver inkjet conductive ink with excellent adhesion was investigated and applied. Nano-silver particles, with dodecylamine (DDA) as the protective agent, were prepared and the effect of protective agent on the post heat-treatment of nano- silver films was investigated. Results of electrical resistance, micro-structural evolution and thermal analysis showed that the Ag/DDA films require a relatively low treatment temperature to convert into conductive materials. Then the conductive ink was prepared with well dispersed Ag/DDA nanoparticles and the ink was printed patterns on PET、PI films through EPSON ME 33 inkjet printer , the patterns showed a sheet resistance is 182.3mΩ/□ and the adhesion reached to 5B after heat-treating at 120°C for 60min .

Preparation of Conductive Nanosilver Ink and its Application on RFID Tags

The recent dramatic progress in the printed electronics and flexible electronics, due to the universality of the substrates including the foldable and stretchable substrates, has opened a new prospect in the field of future electronics. In this paper, silver nanospheres in large-scale are synthesized, the nanosilver ink with 63.88% silver content are prepared and a new type of highly conductive and far identify distance RFID tags are manufactured. Especially there are no resin and other additives containing in our conductive ink which satisfy the rheological characteristics and process of screen printing. The tags exhibit the best radiation performance own to there is no high temperature sintering in need. The surface resistance of the tags could be 80 mΩ/, and the identify distance reach to 6.0m. Keywords:silver nanoparticles, conductive ink, RFID tags

Fabrication of Transparent Conductive Film Using Water-Based Nano-Silver Gravure Ink

In this article, three parts of work have been done. First, silver nano-particle dispersion had been obtained by liquid chemical reduction method with Ag+ concentration as 2.7mol/l and UV-vis, SEM were used to characterize the silver nano-particles. Then, the dispersion was purified by solvent deposit method for three times with acetone acting as the deposit agent and water-based gravure ink was obtained after adding water, resin, and other additives. The silver content and viscosity of the ink were measured by TG and rheometer. Finally, the ink was used to fabricate transparent conductive film (TCF) with PET as the substrate. The transmissivity, adhesion, conductivity, and the edge sharpness were measured. The results show that ration of silver nanoplates in the dispersion synthesized can reach to 70%. From TG curve, the silver content of the ink is wt. 49%. Viscosity of the gravure ink is 129mPa•s. The transmissivity of the film is around 80% and the calculated resistivity is 1.53×10-4Ω.cm.

Influence of Resins on Properties of Copper Screen Printing Conductive Ink

·Copper conductive inks for screen printing are being given great attention due to their widely application in printed electronics industry. In this study, copper conductive ink used for screen printing, which were grinded by three-roll mill machine, was prepared using the epoxy, polyurethane and acrylic resins as adhesive, the flake copper particles which had a diameter between 20 to 50 μm as conductive material and butly alcohol was chosen as solvent. The viscosity and the thixotropy of the conductive ink were measured by rheometer. The oxidation of the surface layer of copper were removed by submerged in a certain concentration of acid solution and the resistance of the sample was measured after heated at different various temperatures. The results showed that the rheology were better for screen printing by adding the acrylic resin and the minimum conductivity can be reached 1.93×10-3 Ω·cm.

Preparation of Water-Based Nano-Silver Gravure Conductive Ink Used for Printed Electronics

Printed electronic industry develops fast and has great potential. In order to prepare water-based nano-silver gravure conductive ink used for printed electronics, liquid chemical reduction method is used. Ag+ (5.89M) at high concentration acting as the precursor is reduced by hydrazine hydrate with PVP as the protecting agent. For one time of reaction, silver content of 9.25% is obtained. After washing and centrifuging the silver colloids for three times to purity, some amount of deionized water, resin and additives are added to the silver paste to fabricated water-based nano-silver conductive ink for gravure. Then, samples obtained by coating or proofing are dried and surface resistance and adhesion are measured. The results indicated that the silver particles prepared have size of about 50~100nm and most of the particles are spherical with small amount nanoplates. The nano-silver gravure conductive ink has 52.63% silver content and 3.58% PVP. Surface resistance of samples coated after sintering at 120°C for 30s can reach 129.5mΩ/sq and the resistivity is 1.49×10-4Ω.cm. The ink layer surface has no drop after 3M method which indicating good adhesion. The ink is suitable for gravure and can be used in printed electronics.

Photoelectric Properties of Metallic Mesh Based on Flexographic Printing

This paper introduces the principle and manufacture process of a film-taped metallic mesh, and the influence of the parameters of metallic mesh film on optical and electromagnetic features has also been analyzed. By using the flexographic printing technology, the metal mesh film with the line widthes of 15, 203040μm and the period of 300μm on PET substrates have been made, and the maximal electromagnetic shield effectiveness is more than 15dB. The results indicate that the optical and electrical performance of the metallic mesh film is inconsistent, and it is better to select a thinner line width and smaller period to obtain optimal shielding effectiveness.

The impact of protective agent on room temperature sintering nanosilver conductive ink

In order to obtain a newly room temperature sintering conductive ink that has great potential applications in printed electronics, especially for some temperature-sensitive substrate, the silver nanoparticles with dodecylamine as the protective agent (Ag/DDA) were prepared, and the effects of protective agent on the insulative–conductive transition time of nanosilver coating at room temperature as well as the stability of nanosilver conductive ink were investigated. The content of the protective agent of Ag/DDA particles was tested by thermogravimetric analysis, and the interaction mechanism between nanosilver and protective agent was studied using Fourier transform infrared spectrometer. In addition, the conductive ink was also prepared with well-dispersed Ag/DDA nanoparticles, and the ink was coated on polyethylene terephthalate and polyimide substrate by Meyer bar (#5). Then, such nanosilver coatings were treated at room temperature to investigate the insulative–conductive transition time. The X-ray diffraction spectra and morphologies of such nanosilver coatings treated at room temperature under different times were also performed. The results showed that the insulative–conductive transition time of the nanosilver coating could be effectively shortened when the protective agent (dodecylamine) is 7.69%. The resulting sheet resistance of the room temperature sintering nanosilver coating after 72 h was 0.15 Ω/sq, which is sufficiently low to be used in printed electronics.

The Preparation of High Concentration Silver Nanoplates with Liquid-Phase Reduction Method

Silver nanoplates, also referred to as nanoprisms or nanodisks, are two-dimensional plasmonic nanostructures that have attracted intensive attention due to their strong shape-dependent optical properties and related applications. In order to obtain the silver nanoplates with high concentration, the liquid-phase reduction method was adopted. Silver nanoparticles colloid was obtained by reducing the high molar concentration of AgNO3 (up to 3.17 M) with the hydrazine hydrate (H4N2 • H2O) as reductant in the presence of polyethylene pyrrole (PVP) as the protectant. 0.5 M Sodium Citrate is introduced into the precursor aqueous which containing AgNO3 and PVP, the molar ratio of PVP to AgNO3 was tuned from 0.64 to 1.5. When molar is 1.5, the mainly particles are silver nanospheres, on the contrary, the nanospheres are transferred into nanoplates as the ratio decreased gradually, until the mainly product are nanoplates. The constituent of the silver nano-clusters was established by performing the Powder X-ray diffraction. The nano-silver dispersion with average diameter is about 113.2 nm were finally deserved. The size distribution of the silver nanoparticles is recorded by the Zeta potential analyzer. Scanning electron microscope (SEM) was used to characterize the morphology of the nano-silver particles. The silver content is about 3%. Nano-silver colloid is obtained and purified by centrifugation and wash with deionized water and ethanol. Then, water-based silver conductive ink is obtained by adding some amount deionized water and additives and adjusted parameters, which could be widely used in printed electronics.

Influence of Post-Processing Methods on the Conductive Properties of Nano-Silver Conductive Ink

The article prepares the jet ink with nano-silver synthesized by the lab and then adjusts the parameters of the silver colloid to fabricate nano-silver conductive ink suitable for ink-jet. Then patterns are obtained on the photo paper through EPSON ME 70 jet printing, and treated by three post-processing methods include laser sintering, heating, and solution soaking, which measured by four- point probe measurement and observed by SEM. It shows that after treatment the surface resistance of the patterns all decrease obviously. Patterns heated at 120°C for 10min, the resistance is 815mΩ/□, while the surface changes of silver layers can be observed obviously from SEM images. But the surface of the photo paper is destroyed with some bubbles on the coating surface. After 10min of laser sintering, the resistance of the silver layer reaches 890mΩ/□ from infinity. And when immersed in the NaCl solution for 5min, the patterns’ surface resistance decrease to 2.7Ω/□.