Optoelectronic properties of blue phosphorene quantum dots: A first principles study

Abstract

In this research, we used first principles methods with density functional theory (DFT) to evaluate simultaneously the electronic and optical properties of defect-free and single-vacancy blue phosphorene quantum dots. We used the generalized gradient approximation of the Perdew-Burke-Ernzerhof (PBE) functional as exchange-correlation functional. We have shown that the band gaps of these quantum dots can be varies in between 2.56 eV and 2.80 eV and the band gap decreases with increasing the system sizes. In the presence of single vacancy, the band gap significantly shrinks resulting from the shift of the conduction band towards the valence band. We also observed additional polaron states close to the Fermi level, indicating the existence of dangling bonds being established by the unbalanced charge Phosphorous atoms surrounding the defect sites. The absorption coefficent increased noticably in the visible light range. The appearance of the polaron states resulted in newly formed absorption peaks in the visible light range. Our results showed the clear effect of defect on light conversion efficiency of solar panels embedding blue phosphorene quantum dots.