High-Precision Printing Sandwich Flexible Transparent Silver Mesh for Tunable Electromagnetic Interference Shielding Visualization Windows.

Flexible transparent conductive films (FTCFs) with electromagnetic interference (EMI) shielding performance are increasingly crucial as visualization windows in optoelectronic devices due to their capabilities to block electromagnetic radiation (EMR) generated during operation. Metal mesh-based FTCFs have emerged as a promising representative in which EMI shielding effectiveness (SE) can be enhanced by increasing the line width, reducing the line spacing, or increasing mesh thickness. However, these conventional approaches decrease optical transmittance or increase material consumption, thus compromising the optical performance and economic viability. Hence, a significant challenge still remains in the realm of metal mesh-based FTCFs to enhance EMI SE while maintaining their original optical transmittance and equivalent material usage. Herein, we propose an innovative symmetric structural optimization strategy to create silver mesh-based sandwich-FTCFs with arbitrary customized sizes through high-precision extrusion printing technology for tunable EMI shielding performance. The meticulous adjustment of xy-axis offsets and printing starting point ensures perfect alignment of the silver mesh on both sides of the transparent substrate. This approach yields sandwich-FTCFs with optical transmittance equivalent to single-layer-FTCFs under identical parameters while simultaneously achieving up to 40% enhanced EMI SE. This improvement stems from the synergistic effect of multiple internal reflections and wave interference between the symmetric silver meshes. The excellent shielding performance of sandwich-FTCFs is evidenced through effectively blocking electromagnetic waves from common devices such as mobile phones, Bluetooth earphones, and smartwatches. Our work represents a significant advancement in balancing optical transmittance, EMI SE, and material efficiency in high-performance and cost-effective FTCFs.