The BSe/GeNGaS van der Waals heterostructures for enhanced optoelectronic and thermoelectric applications: A first-principles perspective

Van der Waals heterostructures (vdWHt), established by stacking dissimilar two-dimensional (2D) materials, present a promising platform for advanced optoelectronic and thermoelectric applications. In this study, BSe/GeNGaS vdWHt—referred to as Model-I and Model-II—were proposed based on first-principles density functional theory combined with semiclassical Boltzmann transport theory. Both vdWHt were confirmed to be energetically and dynamically stable. The two configurations exhibited type-II band alignments with intrinsic electric fields, effectively suppressing the recombination of photo-induced charge carriers. Notably, Model-I exhibited a direct band gap, making it particularly more suitable for integration into optoelectronic devices. Compared with their pristine monolayer counterparts, the vdWHt demonstrated enhanced optical performance, with visible-range absorption extending up to 10⁵ cm⁻¹. The maximum thermoelectric figure of merit (ZT) reached 1.15 for Model-I and 1.05 for Model-II at 700 K, indicating strong potential for high-temperature thermoelectric applications. These findings provide valuable insights for the design and development of next-generation vdWHt-based optoelectronic and thermoelectric devices.