  We have investigated correlated electronic structures and the phase diagram
of electron-doped hydrocarbon molecular solids, based on the dynamical
mean-field theory. We have found that the ground state of hydrocarbon-based
superconductors such as electron-doped picene and coronene is a multi-band
Fermi liquid, while that of non-superconducting electron-doped pentacene is a
single-band Fermi liquid in the proximity of the metal-insulator transition.
The size of the molecular orbital energy level splitting plays a key role in
producing the superconductivity of electron-doped hydrocarbon solids. The
multi-band nature of hydrocarbon solids would boost the superconductivity
through the enhanced density of states at the Fermi level.
