Effects of strain and thickness on the mechanical, electronic, and optical properties of CuTe.

Two-dimensional transition-metal chalcogenides (TMCs) have attracted considerable attention because of their exceptional photoelectric properties, finding applications in diverse fields such as photovoltaics, lithium-ion batteries, catalysis, and energy conversion and storage. Recently, experimentally fabricated monolayers of semiconducting CuTe have emerged as intriguing materials with outstanding thermal and photoelectric characteristics. In this study, we employ first-principles calculations to investigate the mechanical, electronic, and optical properties of monolayer CuTe exhibiting both λ and ζ structures, considering the effects of thickness and strain. The calculations reveal the robust mechanical stability of λ-CuTe and ζ-CuTe under varying thickness and strain conditions. By applying -5% to +5% strain, the band gaps can be modulated, with ζ-CuTe exhibiting an indirect-to-direct transition at a biaxial strain of +5%. In addition, a semiconductor-to-metal transition is observed for both ζ-CuTe and λ-CuTe with increasing thickness. The absorption spectra of λ-CuTe and ζ-CuTe exhibit a redshift with an increase in the number of layers. These computational insights into CuTe provide valuable information for potential applications in nano-electromechanical systems, optoelectronics, and photocatalytic devices and may guide subsequent experimental research efforts.