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Silver-based metal–organic decomposition inks composed of silver salts, complexing agents and volatile solvents are now the subject of much research due to the simplicity and variability of their preparation, their high stability and their relatively low sintering temperature. The use of this type of ink in inkjet printing allows for improved cost-effective and environmentally friendly technology for the production of electrical devices, including flexible electronics. An approach to producing a silver salt-based reactive ink for jet printing has been developed. The test images were printed with an inkjet printer onto polyimide substrates, and two-stage thermal sintering was carried out at temperatures of 60 °C and 100–180 °C. The structure and electrical properties of the obtained conductive lines were investigated. As a result, under optimal conditions an electrically conductive film with low surface resistance of approximately 3 Ω/square can be formed. [ABSTRACT FROM AUTHOR]

Silver-based metal–organic decomposition inks composed of silver salts, complexing agents and volatile solvents are now the subject of much research due to the simplicity and variability of their preparation, their high stability and their relatively low sintering temperature. The use of this type of ink in inkjet printing allows for improved cost-effective and environmentally friendly technology for the production of electrical devices, including flexible electronics. An approach to producing a silver salt-based reactive ink for jet printing has been developed. The test images were printed with an inkjet printer onto polyimide substrates, and two-stage thermal sintering was carried out at temperatures of 60 °C and 100–180 °C. The structure and electrical properties of the obtained conductive lines were investigated. As a result, under optimal conditions an electrically conductive film with low surface resistance of approximately 3 Ω/square can be formed.

Graphical abstract Highlights • The stable reactive silver ink was prepared. • The highly conductive and flexible electrodes was fabricated at 110 °C. • The flexibility of the sintered silver layer were enhanced by HEC. Abstract Stability of conductive ink and mechanical flexibility of conductive pattern are essential for flexible printed electronics. In this work, we reported a stable reactive silver ink for the facile fabrication of flexible electrodes. The ink was mainly composed of silver-isopropanolamine (IPA) complex, formic acid reductant, and hydroxyethyl cellulose (HEC) adhesive agent, and it displayed good chemical stability. The flexible electrodes on polyimide (PI) substrates were achieved by mask-printing and thermal sintering of the ink, and the effects of sintering parameters and HEC adhesive agent content on the electrical and flexible properties and microstructure evolutions of silver layer were systematically investigated. Consequently, the silver layer sintered at 110 °C yields low electrical resistivity of 12.1 μΩ·cm, which is only eight times higher than that of bulk silver. Furthermore, the sintered silver layer still presents excellent flexibility and low relative resistances after the bending, twisting, and folding tests. These results demonstrate that the stable reactive silver ink provides a promising and low cost opportunity for low temperature design and fabrication of high performance flexible printed electronics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The transparent and stable reactive silver ink was prepared. • The highly conductive and flexible printed silver films was fabricated at 70 °C. • The silver film displayed excellent adhesive strength and mechanical flexibility. Abstract To solve the problems of high sintering temperatures (∼200 °C), particle aggregation, nozzle clogging, and poor shelf life of silver nanoparticle inks, we prepared a transparent and stable reactive silver ink for fabricating printed electronics. The ink mainly consisted of ammonia and formic acid ligands, silver acetate, and hydroxyethyl cellulose (HEC) adhesive agent. The highly conductive and flexible silver films were fabricated by printing and low temperature sintering the reactive silver ink, and the effects of sintering temperature and sintering time on the electrical properties of the printed silver films were investigated. Consequently, the printed silver film sintered at 70 °C exhibits good electrical properties with a resistivity of 12.1 μΩ·cm, which is only seven times higher than that of bulk silver (1.65 μΩ·cm). Moreover, the silver film also displays excellent adhesive strength and mechanical flexibility in terms of bending and twisting. [ABSTRACT FROM AUTHOR]

The main problem in preparing stable and printable inks for the inkjet printing of textile substrates is in overcoming their roughness and high sintering temperature. In this study, the modified Tollens’ process for the preparation of a suitable water-soluble ink containing silver for the inkjet printing of textile substrates as a tool for textronic applications was adopted. The choice of this type of ink ensured inkjet printability of textile surfaces with simultaneous sintering at low temperature not exceeding 90 °C. The surface resistance of the inkjet-printed silver layers on all the textile fabrics studied steadily decreased with the number of silver layers deposited. In the case of 8 prints on synthetic textiles made of polyacrylonitrile, polypropylene, polyester and basalt fibres the surface resistance in the range 0.155–0.235 Ω/sq. was achieved. For some textile substrates made of natural fibres and their blends with synthetic fibres, to achieve the proper conductivity an interlayer of acrylic copolymer containing resin was applied. The surface resistance for the same number of prints was in the range of 0.389–0.622 Ω/sq. The study confirmed the usefulness of ink applied in printing silver electrodes and their resistance to bending, washing and dry-cleaning processes. On the basis of these findings, some potential applications in textronic systems, e.g., capacitors, textile heating actuators, textile patch antennas, and high-frequency transmission lines were proposed. [ABSTRACT FROM AUTHOR]

The Laser Direct Synthesis and Patterning (LDSP) technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication. [ABSTRACT FROM AUTHOR]

High conductivity silver pastes are usually incompatible for use with thermally sensitive devices due to their higher sintering temperatures while nanoparticle inks are costly and undergo high particle agglomeration. Effectively transparent contacts (ETCs) have been designed to increase the transmittance, reduce reflectance and overcome shadowing losses in solar cells while enhancing the overall conductivity and charge collection through the grid. In this study, reactive silver ink (RSI) is mixed with a low temperature sintering conductive silver paste (150 °C) for deposition via a microchannel approach. ETCs deposited using the resulting composite were cured at a lower temperature (100 °C) with a conductivity of the order of 103 1/Ω-cm and a transparency >90% in the visible region, promising a reduction in optical and electrical losses when compared to bare transparent conductive oxides. The use of low temperature curing conductive material makes ETCs suitable for use in thermally sensitive optoelectronic and photovoltaic devices, hence they were ultimately deposited on perovskite solar cells and the solar cell parameters were measured. Image 1 • Effectively transparent contacts deposited at low curing temperatures (100 °C) are suitable for thermally sensitive devices. • ETCs offer improved transparency (>90%), high aspect ratio and high conductivity (10^3 1/Ω-cm). • This design mitigates parasitic absorption, reflection and shading losses. • Compositional variations of Reactive Silver Ink were tested to study compatibility with microfluidic approach. • Realization of effectively transparent contacts on perovskites solar cells to explore device performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabric heater was obtained by printing with particle-free silver inks on textiles. • The fabric with low cost, light, and low-voltage fabric heater. • An excellent Joule heating response with high stability. The usage areas of textile materials are expanding day by day and provide different comfort features to the user. In this study, it was focused on designing a fabric with heating feature. By the help of printing particle-free silver inks on textiles, a low-voltage and light-weight fabric heater was produced in wearable form using a low-cost fabrication process. To test the heating properties of the produced fabrics, a computer controlled electronic circuit was designed and implemented. The results proved that the heater designed in this work shows a very good heating performance with low voltage levels, after reaching 55 °C in a short time (<10 s). The heating and cooling patterns exhibit very similar behavior. Moreover, the fabrics with the conductive printed electrodes show durable and robust heating performance in different shapes and voltage levels. One of the most important advantages of this fabric heater is safety, based on the low voltage operation and faster cooling than heating. In addition, this fabric heater has the advantage of being able to be raised to high temperatures with low potential differences. [ABSTRACT FROM AUTHOR]

In this work, a novel technique of inkjet printing e‐textiles with particle free reactive silver inks on knit structures is developed. The inkjet‐printed e‐textiles are highly conductive, with a sheet resistance of 0.09 Ω sq‐1, by means of controlling the number of print passes, annealing process, and textile structures. It is notable that the inkjet process allows textiles to maintain its inherent properties, including stretchability, flexibility, breathability, and fabric hand after printing process. This is achieved by formation of ultrathin silver layers surrounding individual fibers. The silver layers coated on fibers range from 250 nm to 2.5 µm, maintaining the size of interstices and flexibility of fibers. The annealing process, structure of fibers, and printed layers significantly influence the electrical conductivity of the patterned structures on textiles. Outstanding electrical conductivity and durability are demonstrated by optimizing print passes, controlling textile structures, and incorporating an in situ annealing process. The electrical resistance dependence on the strain rate of the textiles is examined, showing the ability to maintain electrical conductivity to retain light‐emitting diode use, stable more than 500 consecutive strain cycles. Most importantly, inkjet‐printed e‐textiles maintain their characteristic washability, breathability, and fabric hands for applications in wearable technology. Inkjet printed e‐textiles with particle free reactive silver inks on knit structures are developed. The inkjet process allows textiles to maintain inherent properties including stretchability, breathability, and fabric hand. This is achieved by formation of ultrathin silver layers surrounding individual fibers. The e‐textiles are highly conductive by means of controlling the print passes, annealing process, and textile structures. [ABSTRACT FROM AUTHOR]

We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive delivery of functional materials.

The Laser Direct Synthesis and Patterning (LDSP) technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication.