Abstract
In recent years, the two-dimensional (2D) materials have received considerable attention for next-generation technological applications due to their unique physical properties. In this article, we explore the energetic stability, electronic, and optical properties of three different PbSe monolayers (such as alpha-, beta-, and gamma- types) for potential optoelectronic and photovoltaic applications. The results presented in this work are obtained from first-principles calculations within density functional theory. The formation and cohesive energies calculated for the PbSe monolayers have been found well-matching to that of stable 2D monochalcogenides which validates their energetic stability. Calculations of the electronic structures show all the three types of monolayers semiconductors in nature with indirect bandgaps of magnitude 0.45, 1.39, and 1.26 eV for alpha-, beta-, and gamma-PbSe respectively. The interband optical transitions taking place within these monolayers are identified from the orbital resolved electronic structures and dielectric functions. The beta-PbSe exhibited isotropic electronic structures and optical spectra whereas a significant degree of anisotropy is seen in the optical spectra of alpha- and gamma- types of PbSe monolayers. The refraction spectra show the transparent nature of these monolayers ranging from near-infrared to a broad range of the ultraviolet spectrum. Moreover, they show substantially low reflectivity and large optical absorption of the incident light. These features advocate effective applications of these novel PbSe monolayers in cutting-edge optoelectronic and photovoltaic devices.