Fabrication of transparent conductive film with flexible silver nanowires using roll-to-roll slot-die coating and calendering and its application to resistive touch panel

Abstract

A transparent conductive film incorporating silver nanowires (AgNW TCF) is fabricated through roll-to-roll (R2R) slot-die coating and a subsequent calendering process and applied to a resistive touch panel. To produce a uniform AgNW film on a flexible polyethylene terephthalate substrate, the R2R slot-die coating is optimized in terms of the solvent, concentration, and flow rate of the AgNW solution, and the length of the AgNWs synthesized using a polyol method. The coated AgNW TCF is calendered between two rolls to produce percolation paths in the film. During the calendering, the roll temperature, applied pressure, and web speed are optimized to yield a low sheet resistance of 28 Omega sq(-1) with a transmittance of 86% at 550 nm. To demonstrate the functionality of the AgNW TCF, a coating of SiO2 microspheres is also applied to form a spacer layer, again using R2R slot-die coating. A resistive touch panel is thus successfully implemented. The effect of the calendering process is confirmed by observing the operation of the touch panel, which is found to be more sensitive and accurate. The integrated manufacturing process for producing an AgNW TCF, presented herein, can be applied to many other major fields.