Rise of asymmetric structures for absorption-dominant electromagnetic interference shielding

Electromagnetic interference shielding is entering a new era in which the goal is no longer to block incident waves, but to control how they enter, propagate, and dissipate within a material. In next-generation electronics, high shielding effectiveness alone is no longer sufficient when it relies on excessive front-surface reflection, causes secondary electromagnetic pollution, adds structural complexity, or conflicts with compact and multifunctional device integration. This review addresses that transition by reframing EMI shielding from conventional reflection-dominant protection to asymmetric, absorption-dominant wave management. It identifies the core limitation of symmetric shields: the same conductive features that suppress transmission also intensify reflection and hinder deep volumetric dissipation. Asymmetric architectures overcome this conflict by programming conductivity, permittivity, permeability, porosity, tortuosity, and boundary conditions through the thickness, thereby converting attenuation into a staged, direction-dependent dissipation process. Within this perspective, nanofiller distribution asymmetry, geometric asymmetry, and surface-coupling asymmetry emerge as a unified design strategy. Janus, alternating, gradient, porous, fibrous, laminated, and segregated structures are therefore understood as interconnected forms of engineered electromagnetic landscapes. By clarifying this mechanistic transition, the review establishes a blueprint for low-reflection, high-absorption, and multifunctional EMI shielding technologies suited to the performance, integration, and intelligence demands of modern electronic systems