Very thin silver nanowires are ideal building blocks for fabricating high-performance transparent conductive films simultaneously with low sheet resistance, high visible light transparency, a small haze factor, and high uniformity. Synthesis of very thin silver nanowires with an average diameter close to 20 nm has been realized by a polyol reduction method in the presence of Br⁻ and Cl⁻ ions. However, nanoparticles contained in the product are detrimental to the overall performance of transparent conductive films, and there have been no methods to purify very thin silver nanowires which are both cost-effective and environmentally friendly. In this work, we report on the Ostwald ripening-driven coarsening of the nanoparticles, followed by sedimentation and brief filtration to separate the particles from very thin silver nanowires. This method is free from the involvement of toxic acetone and could produce very thin silver nanowires with high purity. It is convenient and suitable for large-scale implementation. The films prepared with the purified very thin silver nanowires exhibit a low sheet resistance of 71.3 ± 2.9 Ω □⁻¹ at a high transmittance of 91.7%, a low haze of 1.0%, and a small standard deviation of the sheet resistance of 4.0%, without further treatment processes. The findings in this work will pave the way for the real-world application of very thin silver nanowires towards high-performance transparent conductive films and flexible electronics.

Silver nanowires (AgNWs) have been investigated as alternatives to indium tin oxide in transparent conductive films (TCFs) for electronics. However, AgNW TCFs still pose stability issues when exposed to thermal, chemical, and mechanical stimuli. Herein, we demonstrate a facile and effective route to improve stability by treating the films with dilute ferric chloride solution. Our results indicate that after treatment the films exhibit a dramatically enhanced stability against aging, high temperature oxidation, chemical etching, sulfurization, and mechanical straining. Size-dependent instability is fully explored and explained regarding surface atomic diffusion, which could be blocked by enhancing the activation energy of surface diffusion through forming a AgCl cap under ferric chloride solution treatment. Chemisorption-related Fermi level shift of silver nanowires is applied to tune their chemical reactivity to ferric chloride solution for balancing between size-dependent stability improvement and maintaining optoelectrical properties. Owing to the dilute treatment solution, the treated films exhibit a negligible change in light transmittance, whereas sheet resistance decreases by 30% and flexibility increases because of capillary-force-induced welding of contacting AgNWs and AgCl layer mediated tightening. These findings are significant for real-world applications of AgNW TCFs.

The ability to fabricate electrothermal actuators (ETAs) simultaneously featuring ultrafast response speed (within 0.1 s), large deformation (bending for at least 360°), high figure‐of‐merit (FoM, larger than 0.1%), and low driving voltage (smaller than 1 V) in a single device is extremely important and challenging for their applications in artificial muscles, switches, and microsensors for robotics and biomimetic devices. Herein, an ETA composed of a silver nanowire (AgNW) layer and an ultrathin linear low‐density polyethylene (LLDPE) film with all the aforementioned features is designed. Due to the high conductivity of the AgNW layer and the great difference between the coefficients of thermal expansion of AgNW layer and LLDPE film as well as the huge change in the heat transfer coefficient between flat and rolled ETA, the obtained ETA exhibits an ultrafast response speed of 0.08 s for a bending angle of 360° with a FoM of 0.46% at a low driving voltage of 1 V, over one order of magnitude larger than those of reported ETAs. As a proof‐of‐concept application, the as‐prepared ETAs can be used as intelligent mechanical devices with excellent performance.