Extremely High Mobilities in Two-Dimensional Group-VA Binary Compounds with Large Conversion Efficiency for Solar Cells

The quest for high-mobility nanomaterials with direct band gap is motivated by not only the scientific interest but also the practical need for fabricating the nanoelectronic and optoelectronic devices. Using high throughput first-principles calculations, we have determined the ground-state structures of two-dimensional group-VA binary compounds and explored two stable beta phases of BiAs with unexpected direct band gaps. The proposed BiAs monolayer has extremely high mobility of 8.38 X 10(4) cm(2) V-1 s(-1) close to that of graphene, and furthermore, BiAs is a promising donor material for solar cells. Significantly, our results definitely show that spin-orbit coupling plays a crucial role in exploring the electronic properties of the group-VA binary compounds, as well as studying other compounds with heavy atoms. Our findings pave the way for realizing the nanoelectronic and optoelectronic applications of two-dimensional group-VA binary compounds.