Self-confined electrohydrodynamic printing on micro-structured substrate for flexible transparent electrodes with embedded metal mesh

Flexible transparent electrodes (FTEs) have attracted much attention due to their advantages of excellent optical/electrical conductivities and good mechanical fatigue strength. However, their fabrication presents several challenges, including fabricating wires with a high aspect ratio and sufficient tensile resistance. In this study, an embedded Ag/Cu metal-mesh FTE with a high figure of merit 24,708 (sheet resistance 0.08 Ω/sq and 83.4% optical transmittance) is fabricated through the proposed method called self-confined electrohydrodynamic printing and selective electroplating of Cu. This method employs structured surfaces and patterned hydrophilic/hydrophobic properties to enable highly controllable deposition of solutions (e.g., positioning, line width, consistency), allowing the complete filling of imprinted microgrooves with a high aspect ratio of 2 (e.g., 4 μm width and 8 μm depth) with Ag/Cu metal. Moreover, the resulting FTEs demonstrate good resistance stability under repetitive bending and stretching and exhibit excellent performance in flexible transparent heaters and electromagnetic shielding films.