Strong Intra‐ and Interchain Orbital Coupling Leads To Multiband and High Thermoelectric Performance In Na ₂ Au <i>X</i> ( <i>X</i> = P, As, Sb, and Bi)

ABSTRACT The coupling among electrical conductivity (), Seebeck coefficient (), and lattice thermal conductivity () fundamentally limits thermoelectric performance. Increasing band degeneracy can effectively balance and to achieve a high‐power factor (PF, ), yet highly degenerate electronic structures are uncommon, particularly in low‐symmetry materials. In this work, we propose an unconventional strategy to enhance band degeneracy in zig‐zag‐chain ( P, As, Sb, and Bi) compounds. Strong intra‐chain hybridization between and orbitals, together with unexpectedly strong inter‐chain coupling of states, generates a highly dispersive multivalley valence band that supports large PF. Concurrently, the quasi‐one‐dimensional framework's inherently weak inter‐chain interactions, together with the softened Au– and Au–Au bonds within the chains due to the antibonding – states, lead to a substantial reduction in . First‐principles calculations, integrated with Boltzmann transport theory, confirm that these unique structural and electronic attributes enable ‐type to exhibit high thermoelectric performance. This work establishes a new design paradigm for high‐efficiency thermoelectric materials by harnessing substantial orbital overlap within weakly bonded, quasi‐one‐dimensional systems. The findings open promising avenues for discovering and engineering high‐performance thermoelectric materials.