Quasi-1D selenohalides: first-principles insights into thermoelectric and photovoltaic applications

Abstract

The rapid search for advanced functional materials is increasingly essential to meet the rising global energy demands, secure long-term energy solutions, and achieve a sustainable future. In this work, we systematically investigate the structural, thermoelectric, and photovoltaic properties of quasi-one-dimensional selenohalides XSeHa (X = Sb, Bi; Ha = Cl, Br) using density functional theory. The unique chemical environments, consisting of 1D layers stacked via weak van der Waals interactions, give rise to pronounced anisotropic electron and phonon transport properties alongside nearly isotropic optical behavior. The synergistic combination of favorable electronic features and lone-pair electrons yields a high-power factor (1.74 mW m⁻¹ K⁻²) and a low lattice thermal conductivity (0.31 W m⁻¹ K⁻¹), resulting in a remarkable thermoelectric figure of merit of up to 0.81 at 600 K for BiSeBr. Additionally, strong optical absorption driven by the imaginary dielectric function and favorable excitonic properties achieves a spectroscopic limited maximum efficiency of 31.13% for SbSeBr. Based on these results, BiSeBr and SbSeBr are suggested as promising candidates for experimental exploration in thermoelectric and photovoltaic applications, respectively. This study not only demonstrates the potential of selenohalides but also provides a thorough assessment of their stability and synthesizability to guide future investigations.