One-step aqueous fabrication of a silver nanowire composite transparent conductive film with high uniformity and stability†
Silver nanowire (AgNW) networks are promising candidates for the fabrication of transparent conductive films (TCFs), but the introduction of a top protection layer via a two-step method is generally required to improve the stability, adhesion and roughness of the film. Also, the use of organic solvents in the diluted AgNW coating solution poses a serious hazard due to their evaporation in open air. In this study, a one-step solution process based on a water-dispersed hybrid ink was developed to fabricate composite TCFs with comparable performances. This method significantly simplified the fabrication process, and minimized the chemical hazard. An optimized ratio of chitosan–lactic acid (Chi–LaA) was introduced to an AgNW aqueous dispersion to fabricate a composite TCF with good film coating capability and improved stability. A coefficient of variation of less than 0.1 was found for the composite TCF, which is superior to that of up to 0.49 for the pristine film prepared with an aqueous dispersion. As a result, the Chi–LaA/AgNW (0.2 : 1) TCF exhibited enhanced stability, adhesion, and surface flatness. It showed only a 33% increase in sheet resistance after 300 days in ambient conditions and illustrated 6.6 times the lifetime of the pristine AgNW TCF under a current stress of 250 mA cm−2. Furthermore, it sustained 100 times tape adhesion tests and 13 h of solvent ultrasonic vibration without significant change in its conductivity. Film heaters were fabricated with the Chi–LaA/AgNW composite TCFs, achieving a uniform and stable temperature of ∼135 °C at a low voltage of 6 V with a fast heating rate, good repeatability and long lifetime.