Electronic devices in highly integrated and miniaturized systems demand electromagnetic interference shielding within nanoscale dimensions. Although several ultrathin materials have been proposed, satisfying various requirements such as ultrathin thickness, optical transparency, flexibility, and proper shielding efficiency remains a challenge. Herein, we report an ultrahigh electromagnetic interference (EMI) SSE/t value (>106 dB cm2/g) using a conductive CuS nanosheet with thickness less than 20 nm, which was synthesized at room temperature. We found that the EMI shielding efficiency (EMI SE) of the CuS nanosheet exceeds that of the traditional Cu film in the nanoscale thickness, which is due to high conductivity and the presence of internal dipole structures of the CuS nanosheet that contribute to absorption due to the damping of dipole oscillation. In addition, the CuS nanosheet exhibited high mechanical stability (104 cycles at 3 mm bending radius) and air stability (25 °C, 1 atm), which far exceeded the performance of the Cu nanosheet film. This remarkable performance of nanometer-thick CuS proposes an important pathway toward designing EMI shielding materials for wearable, flexible, and next-generation electronic applications.
Keywords: CuS nanosheet; copper sulfide; dipole structures; electromagnetic interference shielding; ultrathin thickness.