Metallic grid electrode fabricated via flow coating for high-performance flexible piezoelectric nanogenerators

Transparent conducting electrodes (TCEs) based on metallic grid structures have been extensively explored for use in flexible and transparent electronics according to their excellent conductivity and flexibility. Previous fabrication methods have been limited by the complexity and expense of their processes. Here, we have introduced a simple and cost-effective flow-coating method for preparing flexible and transparent metallic grid electrodes using silver nanoparticles (AgNPs). The process comprises only two steps, including patterning and sintering the horizontal AgNPs lines, followed by patterning and sintering the longitudinal AgNPs lines. The grid width could be easily controlled by varying the concentration of the AgNP solution and the grid spacing could be controlled by varying the distance moved by a translation stage between intermittent stops. The optimized Ag grid electrode exhibited an optical transmittance at 550 nm of 86% and a sheet resistance of 174 ω/sq. The resulting Ag grid electrodes were successfully used to prepare a flexible piezoelectric nanogenerator. This device showed good performance, including an output voltage of 5 V and an output current density of 0.5 μA/cm².