First-principles Insights into Predicted High Hole Mobility and Reduced Exciton Binding Energy in Arsenene/al2s3 Van Der Waals Heterostructures

Two-dimensional (2D) materials like arsenene and Al2S3 hold promise for optoelectronics but are limited by wide bandgaps and large exciton binding energies. Here, we design an Arsenene/Al2S3 van der Waals heterostructure and systematically investigate its stability, electronic structure, and optoelectronic properties via first-principles calculations. Our results reveal that the heterostructure exhibits high stability and forms a typical type-II band alignment, which facilitates effective spatial separation of photogenerated carriers. Remarkably, the heterostructure possesses a reduced band gap of 0.81 eV, a high hole mobility reaching the order of ∼104 cm2 V−1 s−1. This mobility value originates from an ideal acoustic deformation-potential model and serves only as a theoretical upper limit rather than a practical device transport parameter, and a significantly decreased exciton binding energy of 310 meV, substantially lower than those of the isolated monolayers. Moreover, the heterostructure demonstrates strong optical absorption across both the visible and ultraviolet regions. These properties position the arsenene/Al2S3 heterostructure as a promising candidate for high-performance optoelectronic applications.