Optoelectronic and photocatalytic properties of GaN, GeS and SiS monolayers and their vdW heterostructures

Using first principles calculations the optoelectronic and photocatalytic properties of GaN, GeS, SiS monolayers, and GaN-GeS/SiS, GeS-SiS van der Waals (vdW) heterostructures are studied for the first time. Initially, it is confirmed that all monolayers and their vdW heterostructures are stable in energy and phonon vibrations, respectively. GaN, GeS, and SiS monolayers are found an indirect energy gap semiconductor with energy gap values are 2.17, 2.25, 2.17 eV, respectively. Type-II band alignment has been observed in GaN-GeS/SiS and GeS-SiS vdW heterostructures which represent application into photovoltaic and energy harvesting devices. Furthermore, charge transfer at the interface of GaN-GeS/SiS and GeS-SiS vdW heterostructures generates an inbuilt electric field which in turn pushing electrons and holes in opposite direction, this can avoid recombination of photogenerated electron-hole pairs. Charge carrier separation inside the materials is the prime criteria for optoelectronic and photocatalytic applications. Upgraded optical features of vdW heterostructures reveal their remarkable absorption of visible light which hold promise for future high-performance photocatalysts and optical devices. Moreover, the suitable band edge positions of GaN, GeS, SiS monolayers, and GaN-GeS/SiS, GeS-SiS van der Waals (vdW) heterostructures relative to the standard electrode potentials at PH = 0, indicates that these materials can be used as a photocatalyst. • Novel vdW heterostructures based on 2D GaN, GeC and SiS (with band gap of 2.17, 2.25, 2.17 eV) have been analyzed. • GaN/GeS(SiS) are direct band gap materials. • Large carrier concentration at interface is observed for each system. • Bader charge population provides sufficient information about charge on each element. • Upgraded optical features of vdW heterostructures reveal their remarkable absorption of visible light. • These systems offer improved photocatalytic activity at pH = 0.