The coupling among electrical conductivity (σ), Seebeck coefficient (S S), and lattice thermal conductivity (κ L ₋) fundamentally limits thermoelectric performance. Increasing band degeneracy can effectively balance σ and S S to achieve a high-power factor (PF, S 2 σ S^2), 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 Na 2 Au Na₂ Au X X (X = X = P, As, Sb, and Bi) compounds. Strong intra-chain hybridization between Au d z 2 Au₃_ₙℂ and X p z X㶅 orbitals, together with unexpectedly strong inter-chain coupling of X p x X䂲 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- X X and Au-Au bonds within the chains due to the antibonding p p - d ∗ d^* states, lead to a substantial reduction in κ L ₋. First-principles calculations, integrated with Boltzmann transport theory, confirm that these unique structural and electronic attributes enable p p -type Na 2 AuBi Na₂ AuBi 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.
Xia et al. (Mon,) studied this question.