External Electric Field-Induced the Modulation of the Band Gap and Quantum Capacitance of F-Functionalized Two-Dimensional Sc₂C

Abstract

The modulation of electronic properties and quantum capacitance of Sc 2 CF 2 under a perpendicular external E-field was investigated using density functional calculations for the potential application of nanoelectronics and nanophotonics. Sc 2 CF 2 has an indirect band gap of 0.959 eV without an E-field. Furthermore, it undergoes a semiconductingmetallic transition under a positive E-field and a semiconductor−insulator transition under a negative E-field. The application of the negative E-field makes Sc 2 CF 2 have an indirect band gap. Sc-d, F-p, and C-p states are mainly responsible for the significant variation of the band gap. Sc 2 CF 2 under an external E-field always keeps the character of a cathode material under the whole potential. Especially, Sc 2 CF 2 under a negative external E-field is more suitable for the cathode material due to its much smaller |Q p |/|Q n | with much higher Q n . The charge analysis is further performed.