Ionic-band insulators are characterized by charge gap, which is given by staggered Ionic potential (Δ). Electronic correlation (U) in these insulators screens the charge gap and makes it smaller than the spin gap. Such correlated band insulators are realized by using simplest model Hamiltonian, i.e., Ionic-Hubbard model. In this work, we have studied Ionic Hubbard model in the weak coupling limit by using non-equilibrium dynamical mean-field theory and iterated perturbation theory as an impurity solver. We find that photo-excited correlated band insulators thermalize rapidly for small charge gaps (Δ) and large interaction strength (U) and they slowdowns thermalization as we decrease the interaction strength (U). For large gaps (Δ), we did not find thermalization for any value of interaction strength.