Outstanding elastic, electronic, transport and optical properties of a novel layered material C 4 F 2 : first-principles study.

Motivated by very recent successful experimental transformation of AB-stacking bilayer graphene into fluorinated single-layer diamond (namely fluorinated diamane C 4 F 2 ) [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 C 4 F 2 by using density functional theory. Our obtained results demonstrate that at the ground state, the lattice constant of C 4 F 2 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 C 4 F 2 is confirmed to be dynamically and thermally stable. C 4 F 2 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 C 4 F 2 . C 4 F 2 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, C 4 F 2 has very high electron mobility, up to 3.03 × 10 3 cm 2 V -1 s -1 , much higher than other semiconductor compounds. Our findings not only provide a comprehensive insight into the physical properties of C 4 F 2 but also open up its applicability in nanoelectromechanical and optoelectronic devices.