Ultraviolet photoelectron spectra were measured using synchrotron radiation for thin films of poly(1,10-phenanthroline-3,8-diyl) (PPhen) and its potassium-doped state. Upon potassium doping of PPhen, two new states, which could be assigned to bipolaron bands, appear in the originally empty energy gap. The electronic structure of the neutral and potassium-doped states was theoretically analyzed using single-scattering approximation combined with semiempirical molecular orbital calculations.