Outstanding elastic, electronic, transport and optical properties of a novel layered material C4F2: first-principles study

Abstract

Motivated by very recent successful experimental transformation of AB-stacking bilayer graphene into fluorinated single-layer diamond (namely fluorinated diamane C₄F₂) [P. V. Bakharev, M. Huang, M. Saxena, S. W. Lee, S. H. Joo, S. O. Park, J. Dong, D. C. Camacho-Mojica, S. Jin, Y. Kwon, M. Biswal, F. Ding, S. K. Kwak, Z. Lee and R. S. Ruoff, Nat. Nanotechnol., 2020, 15, 59–66], we systematically investigate the structural, elastic, electronic, transport, and optical properties of fluorinated diamane C₄F₂ by using density functional theory. Our obtained results demonstrate that at the ground state, the lattice constant of C₄F₂ is 2.56 Å with chemical bonding between the C–C interlayer and intralayer bond lengths of about 1.5 Å which are close to the C–C bonding in the bulk diamond. Based on calculations for the phonon spectrum and ab initio molecular dynamics simulations, the structure of C₄F₂ is confirmed to be dynamically and thermally stable. C₄F₂ exhibits superior mechanical properties with a very high Young's modulus of 493.19 N m⁻¹. Upon fluorination, the formation of C–C bonding between graphene layers has resulted in a comprehensive alteration of electronic properties of C₄F₂. C₄F₂ is a direct semiconductor with a large band gap and phase transitions are found when a biaxial strain or external electric field is applied. Interestingly, C₄F₂ has very high electron mobility, up to 3.03 × 10³ cm² V⁻¹ s⁻¹, much higher than other semiconductor compounds. Our findings not only provide a comprehensive insight into the physical properties of C₄F₂ but also open up its applicability in nanoelectromechanical and optoelectronic devices.