Monolayer Iridium Sulfide Halides with High Mobility Transport Anisotropy and Highly Efficient Light Harvesting.

The discovery and design of two-dimensional semiconductors with high carrier mobilities is of vital importance for high-speed electronic and optoelectronic devices. Herein, based on high-throughput computations, we identify a group of semiconductors, iridium sulfide halides IrSX' (X' = F, Cl, Br, I), with high carrier mobilities (∼103 cm2 V-1 s-1) and highly efficient light harvesting (∼34%). Moreover, these materials exhibit anisotropic in-plane transport behavior, which is switchable via ferroelastic switching, providing the monolayer (ML) IrSX's great potential for applications in direction-controlled high-speed electronic and optoelectronic devices. The high carrier mobility and anisotropic transport are stemming from the anisotropic distribution of 3d orbitals of Ir atoms at the conduction band minimum (CBM) and valence band maximum (VBM) in the rectangular lattices. The ML IrSX's (X' = F, Cl, Br) show good dynamical and thermal stabilities and are thermodynamically stable based on phase diagram calculations, thus meriting experimental realization in the future.