Orbital-Phase Origin of Axis-Dependent Conduction Polarity in One-Dimensional Electrides

Electrides, distinguished by their delocalized interstitial anionic electrons and characterized by low work functions and high charge carrier mobilities, have emerged as promising candidates for advanced devices. In this study, we investigated one-dimensional (1D) electrides featuring channel-confined interstitial electrons to achieve axis-dependent conduction polarity (ADCP) for transverse thermoelectric applications. By developing a simplified tight-binding model, we found that ADCP originates from distinct wave function phase preferences along the in-plane and out-of-plane directions, which enforce a Γ-centered saddle point. In electrides, the presence of interstitial electrons exhibits p_z-orbital-like characteristics, giving rise to a lower energy ADCP-related feature with the same phase curvature reversal. Through first-principles calculations, we proposed that the intrinsic ADCP in the 1D electride Sc₅P₃ is mainly associated with a near Fermi level critical band. Furthermore, this phenomenon can be further tuned through elemental doping and strain engineering. These results reveal a phase-based microscopic origin of ADCP in 1D electrides and suggest electrides as a platform for anisotropic thermoelectric design.