Movement-reactor oven and wire mesh filter for large-scale solvothermal preparation and purification of silver nanowires with high uniformity in length and diameter for the fabrication of low and high haze transparent conductive films
Conventional polyol synthesis has been widely used for the preparation of metal nanowires with different aspect ratios. However, its main drawback is that it is difficult to control the reaction parameters for the shape-controlled synthesis of metal nanowires. Although with the solvothermal method the shape control and growth rate improve, but on a large scale, there are still some challenges such as high reactor weight, long processing time and non-heat uniformity in different positions of the oven. In addition, the purification of nanowires on a large scale is another challenge in this area. Herein, we report the use of a movement reactor oven with the ability to rotate the reactors, and high heat conductive, light-weight reactors for the large-scale preparation of silver nanowires with highly uniform lengths and diameters. The uniformity of the length and diameter of the nanowires using the movement reactor oven in comparison with that using the fixed-reactor oven significantly improved. Furthermore, the amount of silver nanowires increased by 20 times using the new reactor in comparison with the standard Teflon-lined stainless steel reactor for the same reaction time. Reactor rotation, as a new parameter to adjust the final product, was introduced. The synthesized nanowires with and without rotation showed the same morphology and electrical conductivity. For the purification step, first, a new angular filtration method using a wire mesh filter was applied to separate the solvents and ionic impurities, and then by using the same filter based on tangential flow, the nanowires were separated from nanoparticles. Finally, uniform and coffee ring-free transparent conductive films (TCFs) with different haze values were fabricated by coating the formulated silver nanowire ink containing a mixture of green solvents. The fabricated films can be potentially used in a wide range of applications.