Photoelectron spectroscopy is usually described by a simple equation that relates the binding energy of the photoemitted electron, Ebinding, its kinetic energy, Ekinetic, the energy of the ionizing photon, Ephoton, and the work function of the spectrometer, ϕ, Ebinding = Ephoton - Ekinetic - ϕ. Behind this equation there is an extremely rich physics, which we describe here using as an example a relatively simple conjugated molecule, namely coronene. The theoretical analysis of valence band and C1s core level photoemission spectra showed that multiple excitations play an important role in determining the intensities of the final spectrum. An explicit, time-evolving model is applied, which is able to count all possible photo-excitations occurring during the photoemission process, showing that they evolve on a short time-scale, of about 10 fs. The method reveals itself to be a valid approach to reproduce photoemission spectra of polycyclic aromatic hydrocarbons (PAHs).