Cu-S bonding regulates polarization loss in ordered Cu-PEDOT networks under an electromagnetic field.

Conductive polymers have emerged as promising lightweight electromagnetic wave (EMW) absorbers because of their low density, high electrical conductivity, and facile synthesis. However, their intrinsically disordered chain packing and excessive charge transport remain key obstacles to polarization loss regulation and impedance matching optimization. Consequently, simultaneously regulating polarization loss and impedance matching remains a central challenge in conductive-polymer-based EMW absorbers. Here, we develop an interchain coordination strategy to construct a layered Cu-PEDOT coordination polymer network (PEDOT = poly(3,4-ethylenedioxythiophene)), in which Cu-S bonding serves as a molecular handle to regulate polarization loss under an electromagnetic field. Thanks to the tunable Cu-S bonding density, such a platform allows the systematic modulation of the local electronic structure, charge transport behavior, and density of polarization centers. Density functional theory calculations reveal coordination-induced charge redistribution and local electronic asymmetry around the Cu2+ sites. Electron paramagnetic resonance analysis further confirms bonding-density-dependent evolution of polaronic states. Together with the ordered layered architecture and abundant interlayer interfaces, these coordination-regulated electronic features strengthen polarization relaxation while maintaining favorable impedance matching. The optimized Cu-PEDOT-2 achieves a minimum reflection loss of -69.53 dB at 2.5 mm and an effective absorption bandwidth of 6.00 GHz. Overall, this study establishes interchain coordination as a powerful molecular design strategy for balancing charge transport and polarization loss in conductive polymers, providing a rational route toward lightweight high-performance EMW absorbers.