Tunable optoelectronic properties of two-dimensional PbSe by strain: First-principles study

Abstract

Based on first-principles calculations, we studied the band gap, work function and effective mass of two dimensional (2D) PbSe by using applied external in-planed strain. Our results show a linearly decrease trend of band gap under both compressive and tensile axial strain. However, the typical character of direct band gap of 2D PbSe has been changed to indirect with a minimum value about 0.3 eV. In contrast, under biaxial compression, the original type of direct band gap is kept. Under biaxial compression strain, we predict that the optical absorption coefficient of 2D PbSe in the ultraviolet region has significant enhancement. Moreover, we found that the work function of 2D PbSe is sensitive and can be tuned between 3.60 eV and 5.31 eV by applying biaxial strain. In addition, we predict that the decrease of the effective mass of electrons or holes along with the compressive strain can promote the carrier mobility in PbSe monolayer. These results imply that 2D PbSe has potential applications in optoelectronic devices.