Structural, electronic and optical properties of CdO monolayer and bilayers: Stacking effect investigations.

It is well known that the optoelectronic properties of two-dimensional (2D) materials may vary considerably by changing the layers number as well as the stacking order. In this work, the structural, electronic and optical properties of Cadmium oxide (CdO) monolayer and bilayers with different stacking orders are explored using first principles calculations. Simulations assert that the CdO single layer is a direct gap semiconductor with energy gap of 0.811 (1.883) eV as predicted by PBE(HSE06) functional. The bilayer formation leads to the considerable reduction of this parameter, however the direct nature is retained. Results show that the bilayers band gap depends strongly on the stacking order. The charge density maps are indicative of either chemical or physical interlayers interaction of the CdO bilayers. Our optical properties calculations show that the bilayers are more sensitive to the incident light than the monolayer, where the in-plane polarized light can excite more effectively the electronic transitions from the valence band to the conduction band. Additionally, the prospective optoelectronic applicability of the CdO 2D materials studied here is also demonstrated through the capability of absorbing a wide range of electromagnetic radiation with large absorption coefficient. Results reported here are useful covering the lack of knowledge on the optoelectronic properties of the CdO nanomaterials, and may be good guidance for the design of practical applications. • CdO monolayer shows graphene-like planar structure, a buckling height appears in the bilayers. • CdO single is a direct semiconductor material with a band gap of 0.811 (1.883) eV as predicted by PBE(HSE06) functional. • Bilayer formation leads to the considerable reduction of the energy gap, retaining the direct gap feature. • Electronic transitions probability is increased with increasing the layer number. • CdO monolayer and bilayers show good absorption properties of the sunlight. [ABSTRACT FROM AUTHOR]