In this work, we use the tight-binding model to study the low-energy electronic properties of zerodimensional
finite-sized nanographene subject to the influence of an electric field. State energies and
energy spacings are found to oscillate significantly with the field strength. The state energies and band
gaps also rely upon the type of the nanographene. The electric field will modify state energies, alter
energy gaps, and induce the complete energy gap modulations. The band gap of the type-IV
nanographene is always zero regardless of the value of the field strength. The variations of the state
energies will be directly reflected in the density of states. The numbers and frequencies of the density of
states’ divergent peaks are strongly dependent on the field strength and the type of the nanographene.
Finally, the electron wave functions are found to be localized at certain zigzag lines at zero electric field.