Multilayer Three-Dimensional Woven Silver Nanowire Networks for Absorption-Dominated Electromagnetic Interference Shielding

Secondary electromagnetic reflection is a great challenge in the field of high conductivity electromagnetic interference (EMI) material due to the poor electromagnetic absorption ability. In this work, a multilayer stack strategy compositing of the absorption-dominated thin films and the reflection-dominated thick film is proposed to realize both high shielding effectiveness (SE) and low reflection. The film comprises 3D woven silver nanowire (AgNWs) networks embedded in the polydimethylsiloxane (PDMS) substrate, and the shielding film thickness can be adjusted via controlling coating cycles. It can be found the three-ply stack of two thin films and a thick film, (B:F)(10)(B:F)(10)(B:F)(40), (B:F)(5)(B:F)(10)(B:F)(40), and (B:F)(5)(B:F)(5)(B:F)(40), can achieve EMI SEs up to 40.8, 40.7, and 36.3 dB, and the absorptions up to 0.59, 0.65, and 0.69, respectively. Results from verification investigation and theoretical simulation indicate that the multilayer can regulate the shielding mechanism of AgNWs-based films from reflection-dominated to absorption-dominated, with no apparent deterioration of EMI SE. The synergistic effect of a multilayer stack is regarded to originate from a special "absorb-absorb-reflect-absorb-absorb" course. This finding suggests a promising approach to acquiring both high-efficient and absorption-dominated EMI shielding material.