Synthesis of Silver Nanowires by Using Tetrabutyl Ammonium Dibromochloride as the Auxiliary for Low-Haze Flexible Transparent Conductive Films

Tetrabutylammonium Tribromide-Induced Synthesis of Silver Nanowires with Ultrahigh Aspect Ratio for a Flexible Transparent Film

Silver nanowires (AgNWs) have gained significant attention from researchers as a promising material for producing flexible transparent conductive films, which can be utilized in touch and display screens. Thereinto, the ultrahigh aspect ratio AgNW network can theoretically decrease the contact resistance effectively while still retaining considerable mechanical and optical properties. However, fabrication of high-quality AgNWs with a fine diameter and high aspect ratio is still challenging. Herein, a simple and robust approach to synthesize ultrahigh aspect ratio AgNWs is presented. This study successfully fabricated AgNWs with the highest aspect ratio up to ∼4000 and an average length of ∼72 μm by utilizing tetrabutylammonium tribromide as an auxiliary additive. The manifestation of tetrabutylammonium tribromide was proven to be beneficial for the generation of silver seeds and the expansion of AgNWs. The obtained AgNWs were utilized to create a transparent conductive film that showed low sheet resistance of 22.4 Ω/sq and high transmittance and low haze of 87.71 and 4.15%, respectively. The transmittance and haze of the vacant poly(ethylene terephthalate) support were 90.13 and 2.05%, thereby offering great potential for application in flexible transparent electrodes.

Halide-Salt-Free Synthesis of Silver Nanowires with High Yield and Purity for Transparent Conductive Films

To date, silver nanowires (AgNWs) are routinely synthesized. However, the controllable preparation of AgNWs without any halide salts has not reached a similar level. In particular, the halide-salt-free polyol synthesis of AgNWs commonly occurs above 413 K, and the property of AgNWs obtained is not so easy to control. In this study, a facile synthesis of AgNWs with a yield of up to ∼90% in an average length of 75 μm was successfully performed without any halide salts. The fabricated AgNW transparent conductive films (TCFs) show a transmittance of 81.7% (92.3% for the AgNW network only without substrate) at a sheet resistance of 12.25 Ω/square. In addition, the AgNW films show distinguished mechanical properties. More importantly, the reaction mechanism for AgNWs was briefly discussed, and the importance of reaction temperature, the mass ratio of poly(vinylpyrrolidone) (PVP)/AgNO₃, and the atmosphere was emphasized. This knowledge will help enhance the reproducibility and scalability of polyol synthesis of high-quality AgNWs.

Origin of Capillary-Force-Induced Welding in Ag Nanowires and Ag Nanowire/Carbon Nanotube Conductive Networks

Capillary-force-induced welding can effectively reduce the contact resistance between two silver nanowires (AgNWs) by merging the NW-NW junctions. Herein, we report a model for quantifying the capillary force between two nano-objects. The model can be used to calculate the capillary force generated between AgNWs and carbon nanotubes (CNTs) during water evaporation. The results indicate that the radius of one-dimensional nano-objects is crucial for capillary-force-induced welding. AgNWs with larger radii can generate a greater capillary force (F_AgNW-AgNW) at NW-NW junctions. In addition, for AgNW/CNT hybrid films, the use of CNTs with a radius close to that of AgNWs can result in a larger capillary force (F_AgNW-CNT) at NW-CNT junctions. The reliability of the model is verified by measuring the change in sheet resistance before and after capillary-force-induced welding of a series of AgNW and AgNW/CNT conductive films with varying radii.

High-Performance Flexible Transparent Conductive Films Enabled by a Commonly Used Antireflection Layer

Recently, silver nanowire-based transparent conductive films (AgNW-based TCFs) with excellent comprehensive performance have aroused wide and great interest. However, it is always difficult to simultaneously improve the performances of TCFs in all aspects. In this work, by introducing silica nanoparticles (SiO₂-NPs) with a smaller particle size, several properties of AgNW-based TCFs were optimized successfully. The transmittance and conductivity were improved simultaneously, and smaller particle size was proven to be more suitable to achieve TCFs with excellent optoelectrical properties. Typically, an AgNW/SiO₂-based TCF with a sheet resistance of 250 Ω/sq and transmittance of 93.6% (including the poly (ethylene terephthalate) substrate, abbreviated as PET) could be obtained by using SiO₂-NPs with a size of ∼21 nm, and this transmittance is even higher than that of the bare PET (91.8%) substrate. We demonstrated that the layer formed through self-assembly of SiO₂-NPs can cut down the light scattering on the AgNW surface through total reflection, thus leading to a low haze of AgNW/SiO₂-based TCFs. Very interestingly, the SiO₂-NPs conducted away most of the heat generated during laser ablation, protecting the AgNWs from excessive melt and PET from empyrosis, and thus ensuring the TCFs with high transmittance and patterning accuracy. Besides, AgNW/SiO₂-based TCFs have smaller surface roughness, better flexibility, and adhesive force. To the best of our knowledge, the comprehensive performance of the AgNW/SiO₂-based TCFs reaches the highest level among recently reported novel TCFs.

Synthesis and the growth mechanism of ultrafine silver nanowires by using 5-chloro-2-thienylmagnesium bromide as the additive

The presence of 5-chloro-2-thienylmagnesium bromide is beneficial for the in situ formation of smaller AgBr and AgCl particles step by step and the final growth of ultrafine Ag NWs with an average diameter of ∼15 nm and an aspect ratio of over 1000.