The effect of atomic arrangement on photoabsorption of freestanding double-layer honeycomb sheets of zinc selenide
The recently synthesized freestanding four-atom-thick double-layer sheet of ZnSe is a promising material for next-generation ultrathin optoelectronic nanodevices. In this theoretical work, we report two other novel double-layer sheets of ZnSe, with similar stability but distinct structures. These two new double-layer sheets of ZnSe could be considered by cutting along the wurtzite (WZ) bulk instead of the zinc blende (ZB) bulk. All these three layered sheets demonstrate a significantly strong quantum confinement effect, showing a large enhancement of the band gap compared with their three-dimensional (3D) bulks, by state-of-the-art calculations based on quasiparticle GW and the Bethe–Salpeter equation. Furthermore, the optical absorbance shows that the atomic arrangements of these three double-layer sheets of ZnSe play a significant role in the respective distinct photoabsorption behaviors, potentially important for a wealth of applications including solar water splitting.