To fabricate flexible electrodes, conventional silver (Ag) nanomaterials have been deposited onto flexible substrates, but the formed electrodes display limited electrical conductivity due to residual bulky organic ligands, and thus postsintering processes are required to improve the electrical conductivity. Herein, an entirely different approach is introduced to produce highly flexible electrodes with bulk metal-like electrical conductivity: the room-temperature metallic fusion of multilayered silver nanoparticles (NPs). Synthesized tetraoctylammonium thiosulfate (TOAS)-stabilized Ag NPs are deposited onto flexible substrates by layer-by-layer assembly involving a perfect ligandexchange reaction between bulky TOAS ligands and small tris(2-aminoethyl) amine linkers. The introduced small linkers substantially reduce the separation distance between neighboring Ag NPs. This shortened interparticle distance, combined with the low cohesive energy of Ag NPs, strongly induces metallic fusion between the close-packed Ag NPs at room temperature without additional treatments, resulting in a high electrical conductivity of ≈1.60 × 10 5 S cm −1 (bulk Ag: ≈6.30 × 10 5 S cm −1 ). Furthermore, depositing the TOAS-Ag NPs onto cellulose papers through this approach can convert the insulating substrates into highly flexible and conductive papers that can be used as 3D current collectors for energy-storage devices.important basis for developing flexible electrodes in a variety of other energy applications, such as energy-storage/conversion devices, sensors, actuators, and fuel cells, requiring a high electrical conductivity and large surface area.

Here, we report that metal nanoparticle (NP)-based paper/textile electrodes with bulk metallic conductivity can be prepared via organic linker-modulated ligand exchange reaction and in situ room-temperature metallic fusion without additional chemical or thermal treatments. For this study, amine-functionalized molecule linkers instead of bulky polymer linkers were layer-by-layer (LbL)-assembled with tetraoctylammonium bromide (TOABr)-stabilized Au NPs to form Au NP multilayered films. By conversion of the amine groups of the organic molecule linkers from −NH3 + to the −NH2 groups, as well as by a decrease in the size of the organic linkers, the LbL-assembled Au NPs became highly interconnected and fused during LbL deposition, resulting in Au NP multilayers with adjustable conductivity and transport behavior. These phenomena were also predicted by a density functional theory investigation for the model system. Particularly, LbL-assembled films composed of TOABr-Au NPs and diethylenetriamine (M w: ∼104) exhibited a remarkable electrical conductivity of 2.2 × 105 S·cm–1, which was higher than the electrical conductivity of the metal NP-based electrodes as well as the carbon material-based electrodes reported to date. Furthermore, based on our approach, a variety of insulating flexible papers and textiles were successfully converted into real metal-like paper and textile electrodes with high flexibility preserving their highly porous structure. This approach can provide a basis for further improving and controlling the electrical properties of flexible electrodes through the control of organic linkers.

In article number 1806584, Seung Woo Lee, Jinhan Cho, and co‐workers report a room‐temperature metallic fusion‐induced layer‐by‐layer assembly that can produce highly flexible paper electrodes with bulk‐metal like electrical conductivity. The introduced small‐molecule linkers minimize the separation distance between neighboring silver nanoparticles (Ag NPs), and consequently induce the metallic fusion of multilayered Ag NPs at room temperature without additional treatment.

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