  Anisotropic materials, with orientation-dependent properties, have attracted
more and more attention due to their compelling tunable and flexible
performance in electronic and optomechanical devices. So far, two-dimensional
(2D) black phosphorus shows the largest known anisotropic behavior, which is
highly desired for synaptic and neuromorphic devices, multifunctional
directional memories, and even polarization-sensitive photodetector, whereas it
is unstable at ambient conditions. Recently, 2D few-layered As2S3 with superior
chemical stability was successfully exfoliated in experiments. However, the
electronic and mechanical properties of monolayer and bilayer As2S3 is still
lacking. Here, we report the large anisotropic electronic and mechanical
properties of As2S3 systems through first-principles calculations and general
angle-dependent Hooke's law. Monolayer and bilayer As2S3 exhibit anisotropic
factors of Young's modulus of 3.15 and 3.32, respectively, which are larger
than the black phosphorous with experimentally confirmed and an anisotropic
factor of 2. This study provides an effective route to flexible
orientation-dependent nanoelectronics, nanomechanics, and offers implications
in promoting related experimental investigations.
