Inkjet‐Printed Xerogel Scaffolds Enabled Room‐Temperature Fabrication of High‐Quality Metal Electrodes for Flexible Electronics

Abstract

Inkjet-printed metal electrodes with desirable morphologies and electrical properties are indispensable cornerstones for printable and flexible electronics. However, methods to fabricate metal electrodes nowadays mostly request the sintering of printed metal particles, which not only will easily damage heat-sensitive plastic substrates, but also is difficult to achieve a smooth, neat, and highly adhesive electrode structure. Herein, a roomtemperature, solution-processable copper (Cu) electrode is demonstrated to overcome the above issues. The key is to inkjet print a stable xerogel scaffold with high porosity, good uniformity, and smoothness for growing highquality Cu via electroless deposition. Xerogel-based Cu electrodes exhibit a bi-layer architecture, consisting of an upper thin-film Cu (with an electrical conductivity of ≈1.2 × 10 7 S m −1 ) and a bottom Cu-polymer interpenetrated network. The electrodes show an excellent uniformity, surface smoothness, high interfacial energy to the plastic substrates (690-970 mJ m −2 ), and good flexibility. Taking these merits, the electrodes can be patterned onto various plastic substrates and fabricate all-solution-processed electronic devices such as organic thin-film transistors and organic electrochemical transistors with stable electrical performance.

Flexible and Robust Triboelectric Nanogenerators with Chemically Prepared Metal Electrodes and a Plastic Contact Interface Based on Low-Cost Pressure-Sensitive Adhesive

“…We know that metals and polymer films are two incompatible materials; they have different surface energies and Young’s moduli. If the metal electrode film is directly evaporated on the flexible plastic substrate by vacuum deposition techniques, the electrode will extremely readily chip off and cannot pass the scotch tape test, which is approved by our previously reported PAMD-based Cu electrode [ 31 ]. Similarly, if we use the Cu tape as the electrode, it also cannot pass the scotch tape test because the copper tape also uses pressure-sensitive adhesive to attach to the triboelectric layer.…”

“…Fortunately, the electrode produced by this chemical method (i.e., the PAMD technique) can easily pass the adhesive tape test [ 31 ]. In this article, we have used a strong adhesive tape test to perform the pull-off test to further characterize the bond strength between the chemically produced metal electrode and the plastic substrate.…”

“…In manufacturing the flexible and durable G-TENG, we started by replacing the original vacuum-coated electrodes with new highly adhesive and durable electrodes prepared by the chemical solution method, namely polymer-assisted metal deposition (PAMD) techniques [ 27 , 28 , 29 , 30 , 31 ]. PAMD technology is attracting increasing attention from the business and research communities as an emerging technology for the production of highly adherent metal thin films on plastic substrates.…”

Nonpolar Solvent Modulated Inkjet Printing of Nanoparticle Self‐Assembly Morphologies

“…[11][12][13] With perfect photon manipulation capacities, liquid phase synthesized upconversion luminescent nanoparticles (UCNPs) are always used to fabricate different patterns, mainly through the photolithography technique, [14,15] template confined nanoparticles assembly, [16,17] screen printing, [18] inkjet printing, [19][20][21] as well as electrohydrodynamic (EHD) jet [22] and aerosol jet printing. [23] With the advantage of being contact-less, addressable, low-cost, and compatibility with a variety of substrates, inkjet printing shows a facile and versatile patterning approach applied in the fields of flexible electronics, [24,25] biosensors, [26] energy storage, [27] display, [28,29] anti-counterfeit, [30] etc., and the control of the deposits morphology is significant in the performance of the devices. [31,32] EHD jet and aerosol jet printing have the advantage of producing smaller droplet, allowing for high viscosity and fine placement of the ink droplet.…”

A Fast-Responding Electro-Activated Shape Memory Polymer Composite with Embedded 3D Interconnected Graphene Foam

“…The deformation of SMPs is usually thermally actuated and modulated by their heating temperature, but like other polymers, SMPs have very low electrical/thermal conductivity and usually require an external heating device to control their temperature and deformation state, which always increases the design complexity, reduces the deformability and brings unreliability, thus greatly hindering their practical applications [ 5 , 6 , 7 , 8 , 9 , 10 ]. To improve the manipulability of SMPs, various conductive fillers, including carbon black [ 11 ], carbon nanotubes [ 12 ], silver nanoparticles [ 13 ], and copper pastes [ 14 ], have been investigated and added to the SMPs to improve their electrical conductivity.…”