Charge transfer complexes of lithium and chlorine atoms with biphenyl (BP) dimers have been studied as models for intermolecular polarons and bipolarons by means of density functional calculations. Sandwich-type complexes BP-nX-BP, (X =Li,Cl and n = 1,2), 'top' complexes nX-BP-BP and the charged complexes [BP-BP]n± were considered. Stable dimer structures with stabilization energies ranging from -15 to -71 kcal/mol are found when doping atoms are included. In the case of charged complexes without counterions the interaction energy is only a few kcal/mol. Specific differences in the positions of the doping lithium and chlorine atoms are observed: the lithium atoms are located inside the bilayer formed by the two BP molecules whereas the chlorine atoms are located at the edges.