Double layered design for electromagnetic interference shielding with ultra-low reflection features: PDMS including carbon fibre on top and graphene on bottom

Electromagnetic interference (EMI) shielding materials with low reflection features have become necessary for a new generation of electronic devices to reduce secondary electromagnetic pollution . Here, a novel strategy is adopted to provide flexible polydimethylsiloxane (PDMS) composite films with ultra-low reflection EMI shielding performance by constructing a double-layer structure with uniformly dispersed carbon fibres (CFs) in the upper layer as an impedance-matching absorption layer and continuous graphene fibres (GFs) located at the bottom layer as a conductive reflection layer. The resulting specific structure significantly reduces the reflectivity of the composite film at extremely low carbon conductive fillers (0.01 wt% CFs and 1.00 wt% GFs) through the process of “absorption-reflection-reabsorption” when incident electromagnetic waves (EMWs) pass through the composite film: the total shielding effectiveness ( SE Total ) achieves 34.4 dB at 18.0 GHz, while the shielding effectiveness of reflection ( SE R ) is only 0.1 dB, and reflection coefficient ( R ) is as low as 0.018. This phenomenon indicates that 1.8% of the incident EMWs are reflected in the propagation process when 99.96% are attenuated. In addition, the shielding mechanism of the double-layer EMI shielding composite films with low reflection features is studied in depth. This study provides a reliable idea for designing flexible EMI shielding materials with ultra-low reflection to alleviate secondary electromagnetic radiation pollution.