In the following, we further investigate the robustness of the polaron induced in Proton-1 configuration. First, we introduce chlorobenzene (ε = 5.6968) as a solvent which leads to formation of spin-symmetric electronic states for all proton positions. The corresponding LUMO of Proton-1 is shown in Fig. . The absence of spin-symmetry breaking and the formation of a localized LUMO just like for Proton-2 without solvent (cf. Fig. ) indicates that the polaron formation is hindered by screening from the solvent. Next we investigate the influence of a nearby BCF:OH - counter anion. Placing a pre-optimized BCF:OH -counter anion above Proton-1 and optimizing the complex with 0 net charge in gas-phase leads to a slightly curved structure of the polymer. The calculated electronic structure shows +0.78e net charge on the protonated polymer, and -0.78e on the BCF:OH -counter anion as shown in Fig. , demonstrating that the counter anion and the proton attached to the polymer do not neutralize each other by recombining to a BCF:H 2 O complex. However, for this complex, spin-symmetric electronic states are formed with a LUMO very much resembling the LUMO of Proton-1 in chlorobenzene (cf. Fig. and), indicating that the polaron formation on the polymer is also hindered by the presence of the counter anion. After removal of the anion and calculation of the electronic density without further geometry optimization with +1e net charge, a symmetry-broken electronic state is recovered with a polaron formed in the β -SUMO. These results indicate that the interaction between the counter anion and Proton-1 hinders polaron formation, whereas the geometry distortion plays only a minor role.