Two-dimensional Janus SeMoZAZ′ (A = Si, Ge; Z = N, P, As; Z ≠ Z′): multifunctional properties for electronic, piezoelectric and photocatalytic applications

Abstract

Due to the disruption of symmetry in the vertical direction, two-dimensional Janus materials exhibit unique properties, making them promising for a wide range of applications. In this paper, we conducted first principles calculations to investigate several novel Janus SeMoZAZ′ (A = Si, Ge; Z, Z′ = N, P, As; Z ≠ Z′) monolayers. Our research revealed that 10 out of 12 structures demonstrate excellent stability and mechanical properties. Employing the HSE06 functional, 7 out of 10 stable structures displayed semiconductor properties, while the remaining three structures exhibited metallic properties. Among the semiconductor structures, calculations showed a significant piezoelectric coefficient. Notably, SeMoPSiN, SeMoAsSiP, and SeMoAsGeP monolayers displayed favorable band edge positions, wide light absorption, high solar-to-hydrogen efficiency (up to 31.55%), and larger hole carrier mobility in the y-direction (8171.06 cm² s⁻¹ V⁻¹). We further investigated the effect of biaxial strain on SeMoZAZ′ monolayers, and interestingly, the SeMoPGeN monolayer demonstrated the capability to undergo photocatalytic water splitting under biaxial strain. Our research suggests that 2D Janus SeMoZAZ′ (A = Si, Ge; Z, Z′ = N, P, As; Z ≠ Z′) materials hold great potential for applications in photocatalysis, electronics and sensors.