First-principle calculation of a novel semiconductor carbon allotrope: oc-C24 and its distinct strain response

Novel semiconductor material with both high strength and ductility is urgently needed to meet the demands of increasing complex applications for electronic components. However, overcoming the inherent trade-off between strength and ductility has remained a longstanding challenge in materials science research. Herein, we proposed a three-dimensional carbon allotrope, oc-C24 with pure sp2 hybridization. This structure comprises arrays of carbon chains in an “8”-shape helix configuration, in between the C-chains which interlinked by the oriented ethylene with a planar π-conjugation. The distinctive structural unit imbues oc-C24 with remarkable tensile behavior, characterized by multi-stage chemical bond rearrangements and structural phase transitions along [010] crystallographic direction, displaying multi-level stress re-enhancement phenomena. A tensile strength of 104.2 GPa and a record strain of 1.05 are observed along [010] direction. Electronic band analysis reveals that oc-C24 is a semiconductor with an indirect band gap of 2.91 eV. The impressive tensile resistance and ductility of oc-C24 suggest its strong potential applications in electronic devices under extreme conditions. Our findings offer valuable insights and methodological strategies for designing novel carbon allotropes with unique mechanical responses.