Puckered C18-carbon: a novel 2D carbon phase with a direct band gap.

The pursuit of new two-dimensional (2D) carbon allotropes with semiconducting characteristics has long been a focal point in the field of materials science. In this study, a novel 2D carbon allotrope with an intrinsic semiconducting nature has been theoretically proposed within first-principles approach. This new 2D carbon allotrope possesses a puckered carbon framework with mixed sp 2 +sp 3 hybridization, referred to as puckered C18-carbon. Its superior structural stability is strongly supported by the calculations of cohesive energy, phonon dispersion, and elastic constants, in addition to ab initio molecular dynamics simulations at temperatures up to 800 K. Furthermore, the associated mechanical, electronic, and optical response properties of the new carbon phase have been systematically revealed in this study.Notably, this puckered carbon sheet exhibits semiconducting behaviors, featuring a wide direct band gap that can be further modulated by applying biaxial strain. The appealing features of the proposed new 2D carbon phase, including its superior structural stability, high mechanical strength, direct semiconductor characteristics, along with an extraordinary optical response in the blue and ultraviolet regime, render it a promising candidate for use in future carbon nanoelectronic, optoelectronic, photovoltaic, and visible-light emitting devices.