  Superconductivity in organic conductors is often tuned by the application of
chemical or external pressure. With this type of tuning, orbital overlaps and
electronic bandwidths are manipulated, whilst the properties of the molecular
building blocks remain virtually unperturbed.Here, we show that the excitation
of local molecular vibrations in the charge-transfer salt
$\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br$ induces a colossal increase in carrier
mobility and the opening of a superconducting-like optical gap. Both features
track the density of quasi-particles of the equilibrium metal, and can be
achieved up to a characteristic coherence temperature $T^* \approxeq 50 K$, far
higher than the equilibrium transition temperature $T_C = 12.5 K$. Notably, the
large optical gap achieved by photo-excitation is not observed in the
equilibrium superconductor, pointing to a light induced state that is different
from that obtained by cooling. First-principle calculations and model
Hamiltonian dynamics predict a transient state with long-range pairing
correlations, providing a possible physical scenario for photo-molecular
superconductivity.
