Development of scalable cross-flow purification process for transparent conductive film quality silver nanowires

Silver nanowires (Ag NWs) exhibit high conductivity and excellent light transmittance, making them suitable for use in flexible displays, touch panels, and solar cells. However, Ag NWs synthesized using methods such as the polyol process contain a significant number of silver nanoparticles (Ag NPs) and short nanowires, especially during large-scale production, which hinders the formation of a conductive network of long silver nanowires, thereby reducing both optical and electrical performance. In this study, we developed a purification process for Ag NWs using a cross-flow method, effectively removing unwanted components by selectively retaining long Ag NWs that cannot pass through the filtration membrane. During development, we investigated several process variables, including the type of circulation pump, pump shaft shielding method, ceramic filter material, pore size, flow rate, pressure, and liquid temperature, and improved the cross-flow apparatus. Compared with traditional flocculation-dispersion purification, this technique reduces the use of organic solvents, thereby reducing environmental impact, minimizing structural damage to the NWs, and enabling continuous processing and scalability. After parameter screening of the synthesis conditions for Ag NWs via the modified polyol method and purifying the suspension using the modified cross-flow method, we produced a transparent conductive film from a dispersion of Ag NWs with a short axis of 20 nm and a long axis of 13 μm. The resulting material exhibited a sheet resistance of 30.12 Ω/sq, a haze of 0.81%, and a transmittance of 98.47%, confirming the method’s effectiveness and its potential for scalable production and practical applications due to its low resistance, high transmittance, and minimal haze. The AgNW recovery yield under the selected operating conditions was 33% for Ag NWs meeting the target specification of 20 nm in diameter and 13 μm in length.