导电油墨及其印刷技术的研究进展

目的 综述导电油墨及其印刷方式的研究进展,为开发价格低廉、性能稳定、导电性优良的导电油墨提供参考。方法 通过查阅文献归纳各类导电油墨的制备方式、印刷方式和应用领域,对导电油墨进行系统分类,比较各类导电油墨的性能和优缺点,并对其印刷技术进行分析,展望了导电油墨的发展前景。结果 目前关于导电油墨的研究集中在纳米银、纳米铜、石墨烯等导电填料的低温烧结油墨,主要采用丝网印刷、喷墨印刷等印刷方式,多用于制备传感器、柔性可穿戴设备等。未来的研究仍需关注如何低成本、低能耗、简单大量地制造导电油墨。结论 导电油墨的制备将与环境友好型的印刷方式相结合,向高导电性、高印刷适性发展,成为印刷电子领域的关键技术。     

纳米银导电油墨及其在柔性印刷电子中的应用

目的 探究纳米银导电油墨及其在柔性印刷电子中的应用。方法 通过总结国内外文献,从纳米银颗粒及其导电油墨的制备、印刷工艺、烧结工艺以及在柔性印刷电子技术中的应用几方面总结近年来的研究进展。结果 在油墨制备及使用中,简化制备工艺、降低生产成本、实现绿色环保、低温烧结,同时提高油墨的基材适应性是未来纳米银导电油墨的改进重点。直写技术具有精度高、速度快等优势,正逐渐替代丝网印刷技术成为主流。烧结工艺的研究重点在于实现低温烧结,其中化学烧结工艺简单,但提高导电性是研究重点。其他烧结方式则设备昂贵,环境要求高。结论 作为功能性电子材料,纳米银导电油墨因出色的电性能和印刷适性,正在被广泛应用于柔性印刷电子中。近年来通过对纳米银及其导电油墨的深入研究及技术改进,在纳米银颗粒的制备、低温烧结技术、节能环保加工工艺等方面获得了一定的进展。与此同时,将其作为功能材料应用于制备柔性传感器中,RFID标签天线、柔性电极、超级电容器、太阳能电池等正受到广泛研究与应用。     

Turning Trash into Treasure: Additive Free MXene Sediment Inks for Screen-Printed Micro-Supercapacitors

Printed functional conductive inks have triggered scalable production of smart electronics such as energy-storage devices, antennas, wearable electronics, etc. Of particular interest are highly conductive-additive-free inks devoid of costly postdeposition treatments to eliminate sacrificial components. Due to the high filler concentration required, formulation of such waste-free inks has proven quite challenging. Here, additive-free, 2D titanium carbide MXene aqueous inks with appropriate rheological properties for scalable screen printing are demonstrated. Importantly, the inks consist essentially of the sediments of unetched precursor and multilayered MXene, which are usually discarded after delamination. Screen-printed structures are presented on paper with high resolution and spatial uniformity, including micro-supercapacitors, conductive tracks, integrated circuit paths, and others. It is revealed that the delaminated nanosheets among the layered particles function as efficient conductive binders, maintaining the mechanical integrity and thus the metallic conductive network. The areal capacitance (158 mF cm⁻²) and energy density (1.64 µWh cm⁻²) of the printed micro-supercapacitors are much superior to other devices based on MXene or graphene. The ink formulation strategy of “turning trash into treasure” for screen printing highlights the potential of waste-free MXene sediment printing for scalable and sustainable production of next-generation wearable smart electronics.     

聚噻吩基导电油墨的制备及其印刷适性研究

聚噻吩及其衍生物具有高导电性、环保性、热稳定性等优点,将其 制备成导电油墨,在印刷电子和智能包装等领域中极具应用前景。本文以聚（3, 4- 乙撑二氧噻吩）（PEDOT）、导电炭黑（CB）以及羧甲基纤维素钠（CMC） 为主体,采用原位聚合法制备了 PEDOT-CB/CMC 导电油墨。系统地研究了 连接料、辅助添加剂及烧结温度等对油墨黏度、附着力、分散性和导电性能 的影响;并借助于丝网印刷技术对油墨的印刷适性进行了研究。结果表明, 导电油墨具备良好的分散性和附着力;印品经烧结处理后,其电阻值明显下 降并随墨条长度、宽度的增加呈现规律性变化。另外,导电油墨在纸、塑料、 棉布等不同基材上均能满足丝网印刷的要求。     

液态金属基油墨的印刷适性调控与可拉伸电子应用

目的 调整液态金属基油墨的印刷适性，用于可拉伸电极的印刷法构建。方法 通过超声破碎法减小液态金属微粒直径，降低其表面张力;探究聚氨酯种类和含量对液态金属微粒的分散性、油墨流变性、电极的印刷适性和可拉伸性的影响。结果 引入PU1185制备的液态金属油墨，丝印电极分辨率达58 µm;印制电极展现了良好的导电性和可拉伸性，预拉伸稳定后的电极在100%的应变下拉伸1 000次，电阻变化不超2倍。结论 液态金属基油墨能够用于高分辨电路的加工，在可拉伸电子领域具有可预见的应用前景。     

高岭土对水性油墨印刷适性的影响研究

目的 探究高岭土加入调墨油中对水性油墨印刷适性影响。方法 使用高岭土制备冲淡剂,然后加入不同含量的冲淡剂配置3种调墨油,再将这3种调墨油与5种不同的色浆分别配置成油墨,最后从防滑度、黏度、pH值、鼓泡、沉底、细度、呈色效果等方面考察其印刷适性。结果 冲淡剂加入调墨油中会稍微降低水性防滑油墨的防滑度,但不影响油墨的pH值、细度和呈色效果。样2调墨油由于冲淡剂含量较大,所以沉底现象很明显,可能会影响到油墨的印刷适性。结论 使用质量分数为10%～12%调墨油配置的水性油墨满足印刷要求,对水性油墨的配置及使用范围具有一定参考意义。     

Silver content effect on rheological and electrical properties of silver pastes

The novelty of this work is laboratory formulation of environmentally friendly, water-based silver inks adapted for screen printing. The challenge was also to elaborate inks that can withstand temperatures as high as 900 °C. Indeed, when printed on ceramic substrate, they were sintered at these high temperatures. These inks can replace conductive silver pastes present in the market, today, and containing irritant solvents such as terpineol and other aromatic solvents. Besides, screen printing is considered as an additive technique, thus allowing reducing wastes. Furthermore, only with 72.5% silver, considered as low content compared to commercial inks (≥75%), prepared inks presented good electrical resistivity, 23 nΩ m, close to that of bulk silver resistivity, 16 nΩ m. Formulation of silver inks with spherical particles, 2–3 μm mean diameter, was performed. The aim of the study was to determine silver content effect on pastes rheological behaviour, lines properties (width, thickness and roughness) and electrical properties. Therefore, rheological behaviour of inks was studied; in particular, Casson and Bingham models were applied in order to determine the yield stress. Viscosity evolution as a function of shear rate was also determined. Besides, the thixotropic behaviour of inks was highlighted. Inks were then screen printed on alumina sintered substrates and cured at different temperatures during 15 min. Topography measurements were performed. Line resistivity as small as 35 nΩ m was measured on cured lines. These inks, printed on ceramic tapes, can be used to print microwave transmission lines, for which resistivities lower than 1 mΩ m are requested.     

Printable Transparent Conductive Films for Flexible Electronics

Printed electronics are an important enabling technology for the development of low‐cost, large‐area, and flexible optoelectronic devices. Transparent conductive films (TCFs) made from solution‐processable transparent conductive materials, such as metal nanoparticles/nanowires, carbon nanotubes, graphene, and conductive polymers, can simultaneously exhibit high mechanical flexibility, low cost, and better photoelectric properties compared to the commonly used sputtered indium‐tin‐oxide‐based TCFs, and are thus receiving great attention. This Review summarizes recent advances of large‐area flexible TCFs enabled by several roll‐to‐roll‐compatible printed techniques including inkjet printing, screen printing, offset printing, and gravure printing using the emerging transparent conductive materials. The preparation of TCFs including ink formulation, substrate treatment, patterning, and postprocessing, and their potential applications in solar cells, organic light‐emitting diodes, and touch panels are discussed in detail. The rational combination of a variety of printed techniques with emerging transparent conductive materials is believed to extend the opportunities for the development of printed electronics within the realm of flexible electronics and beyond.     

Additive-Free Aqueous MXene Inks for Thermal Inkjet Printing on Textiles

Direct printing of functional inks onto flexible substrates allows for scalable fabrication of wearable electronics. However, existing ink formulations for inkjet printing require toxic solvents and additives, which make device fabrication more complex, limit substrate compatibility, and hinder device performance. Even water-based carbon or metal nanoparticle inks require supplemental surfactants, binders, and cosolvents to produce jettable colloidal suspensions. Here, a general approach is demonstrated for formulating conductive inkjet printable, additive-free aqueous Ti₃C₂T_x MXene inks for direct printing on various substrates. The rheological properties of the MXene inks are tuned by controlling the Ti₃C₂T_x flake size and concentration. Ti₃C₂T_x-based electrical conduits and microsupercapacitors (MSCs) are printed on textile and paper substrates by optimizing the nozzle geometry for high-resolution inkjet printing. The chemical stability and electrical properties of the printed devices are also studied after storing the devices for six months under ambient conditions. Current collector-free, textile-based MSCs show areal capacitance values up to 294 mF cm⁻² (2 mV s⁻¹) in poly(vinyl alcohol)/sulfuric acid gel electrolyte, surpassing reported printed MXene-based MSCs and inkjet-printed MSCs using other 2D nanomaterials. This work is an important step toward increasing the functional capacity of conductive inks and simplifying the fabrication of wearable textile-based electronics.     

Hybrid 3D Printing of Soft Electronics

Hybrid 3D printing is a new method for producing soft electronics that combines direct ink writing of conductive and dielectric elastomeric materials with automated pick‐and‐place of surface mount electronic components within an integrated additive manufacturing platform. Using this approach, insulating matrix and conductive electrode inks are directly printed in specific layouts. Passive and active electrical components are then integrated to produce the desired electronic circuitry by using an empty nozzle (in vacuum‐on mode) to pick up individual components, place them onto the substrate, and then deposit them (in vacuum‐off mode) in the desired location. The components are then interconnected via printed conductive traces to yield soft electronic devices that may find potential application in wearable electronics, soft robotics, and biomedical devices.     

The influence of carbon morphologies and concentrations on the rheology and electrical performance of screen-printed carbon pastes

Screen-printing inks containing various morphologies of carbon are used in the production of a variety of printed electronics applications. Particle morphology influences the rheology of the ink which will affect the deposition and therefore the electrical performance of a printed component. To assess the effect of both carbon morphology and concentration on print topography and conductivity, screen printable carbon inks with differing loading concentrations of graphite, carbon black and graphite nanoplatelets (GNPs) were formulated, printed and characterised, with rheological and novel print visualisation techniques used to elucidate the mechanisms responsible. Carbon morphology had significant effects on the packing of particles. The smaller carbon black particles had more interparticle interactions leading to better conductivities, but also higher ink viscosities and elasticities than the other morphologies. Increases in carbon concentration led to increases in film thickness and roughness for all morphologies. However, beyond a critical point further increases in carbon concentration led to agglomerations of particles, mesh marking and increases in surface roughness, preventing further improvements in the print conductivity. The optimal loading concentrations were identifiable using a custom-made screen-printing apparatus used with high speed imaging for all morphologies. Notable increases in filamentation during ink separation were found to occur with further increases in carbon concentration beyond the optimum. As this point could not be identified using shear rheology alone, this method combined with shear rheology could be used to optimise the carbon concentration of screen-printing inks, preventing the use of excess material which has no benefit on print quality and conductivity.

     

Ink Tuning for Direct Ink Writing of Planar Metallic Lattices

316L and Cu-based inks are developed to 3D-printed tetrachiral auxetic structures. The main objectives of the work are to study the effects of powders composition and powder:binder volume ratio on rheological properties and printability of the inks. Following these results, customized Gcode is developed using FullControl Gcode Designer open-source software to 3D print intricate tetrachiral auxetic structures. The results reported in this work show how powder composition (316L versus Cu) has less effect on the inks’ rheological behavior than powder size distribution and powders:binder volume ratio. In terms of rheological parameters, the zero-shear rate viscosity mainly affects the capability of the printed ink to retain its shape after printing, while the yield stress affects the printability. The printed and sintered auxetic structures achieve the intended lattice-geometry design.     

新型水性导电油墨的制备与性能研究

以水性聚氨酯和水性丙烯酸树脂的混合液为连接料,以炭黑为导电填料,制备了一种新型的水性导电油墨。利用丝网印刷了标准电路并进行检测,分析了水性导电油墨的导电性能与印刷适性。检测结果表明,制备出的水性导电油墨具有导电力强、附着性能优良和抗弯曲能力强的优点,非常适用于制作柔性电路。     

Rheological properties and related screen-printing performance of low-temperature silver pastes for a-Si:H/c-Si heterojunction solar cells

Four different low-temperature silver pastes were utilized to make metal grids by screen printing for silicon heterojunction solar cells. The rheological behaviors of the low-temperature silver pastes were characterized by viscosity test, thixotropy test, oscillatory stress sweep test and creep-recovery test. The correlationship between the screen-printing performance and the rheological properties was investigated. It was found that the shear thinning behavior and the thixotropy behavior of the silver pastes were desirable for the screen-printing process. An obvious viscoelastic behavior of the silver paste was also helpful for improving its printability. Further, good recovery and low creep and recovery compliances could minimize the printing defects and the tendencies to bleed out during the screen-printing, and thus increase the aspect ratio of the printed grids.     

Inkjet printing of multi-walled carbon nanotube/polymer composite thin film for interconnection

In this paper, multi-walled carbon nanotube (MWCNT) ink was selectively patterned by inkjet printing on substrates to form conductive traces and electrodes for interconnection application. MWCNT was firstly functionalized using concentrated acid and dispersed in deionized water to form a colloidal solution. Various concentrations of MWCNT were formulated to test the stability of the solution. The printability of the MWCNT ink was examined against printing temperature, ink concentration and ink droplet pitch. Rheological properties of the ink were determined by rheometer and sessile drop method. The electrical conductivity of the MWCNT pattern was measured against multiple printing of MWCNT on the same pattern (up to 10 layers). While single layer printing pattern exhibited highest resistance, the CNT entangled together and formed a random network with more printed layers has higher conductivity. The electrical properties of the printed film was compared to a composite ink of CNT and conducting polymer (CNT ink was mixed with conductive polymer solution, Poly(3,4-ethylenedioxythiophene)-Poly(styrenesulfonate) (PEDOT:PSS)). Scanning electron microscopy (SEM) was used to observe the surface structure and atomic force microscopy (AFM) was used to study the morphology of the printed film under different conditions.     

金属纳米颗粒导电墨水制备与后处理工艺的研究进展

印刷电子技术是一种低成本、简捷高效、绿色环保的电子器件制造技术,已在柔性电子制造等诸多领域展现出巨大的潜力。近年来,导电墨水作为印刷电子技术迅速发展的关键材料受到了学术界的广泛关注和报道。结合印刷电子技术的应用和发展现状,对金属纳米颗粒导电墨水的各项性能指标及其机理进行概述,综述了金属纳米颗粒导电墨水的制备和后处理工艺的研究进展,着重介绍了部分有潜力的前沿技术,并分析了这些技术对应的优势与局限及其发展方向。最后结合印刷电子技术目前发展中存在的问题提出了一些观点。     

Recent Development of Printed Micro-Supercapacitors: Printable Materials,Printing Technologies,and Perspectives

The rapid progression of portable and wearable electronics has necessitated the development of high-performing, miniaturized energy-storage devices with flexible form factors and high energy and power delivery. Printed micro-supercapacitors (MSCs), with in-plane interdigital configurations, is touted as a promising choice to fulfill these requirements. New printing technologies can assemble MSCs with fiscal and environmental benefits, large form factors, and at high throughputs, qualities not afforded with conventional microfabrication technologies. Here, recent progress in the preparation of functional ink systems for wearable MSCs, encompassing electrode materials, conductor materials, and electrolytes, is presented. First, a comprehensive background of the fundamentals of printing technology is introduced, with discussions focusing on methods of improving ink functionality while simultaneously retaining good printability. Second, various printing techniques to ensure manufacturable scaling of wearable MSCs with high areal electrochemical performance and small footprint are explored. Within the scope of these two topics, various issues that hinder the full materialization of widespread adoption of printed MSC and next steps to overcome these issues are discussed. Further deep dives in scientific and technical challenges are also presented, including limited functionality of the inks, low printing resolution, overlay accuracy, and complex encapsulation.     

镓基液态金属导电油墨及其图形化应用

目的 提出发展液态金属导电油墨的基本途径及其对信息产业发展重要性。方法 从导电油墨的制备方法、液态金属粒子的物理特性、液态金属油墨图形化及其应用展开论述,全面总结液态金属导电油墨的技术现状以及深化对其的认识。结果 液态金属基导电油墨将比目前贵金银基导电油墨的成本低50倍,基于液态金属的导电油墨图形化印刷电子在智能防伪包装、柔性电子、生物医用等领域呈快速发展趋势。结论 镓基液态金属导电油墨及其印刷技术是一个崭新的技术革命,具有重要的研究价值和经济意义。