We observe that the π-band (VB-2) lies below the VB and, as a consequence, the energy of the CB is lowered, i.e. it lies closer to the Fermi level. The energetic distance between VB and VB-2 in the intercalation free monolayer of PTI-IF is approx. 0.3 eV at Γ (Figure ) and the CB position (or electron affinity) is 3.7 eV. Repeating this calculation for PTI-LiBr, we obtain an electron affinity of 4.2 eV; a value that allows environmentally stable n-transport. To estimate the strength of the VB-2 → CB transition, we determined the absorption coefficients of PTI-IF and PTI-LiBr. The obtained absorption coefficients point towards a direct π → π* (VB-2 → CB)-transition in both materials (9032 M -1 cm -1 for PTI-IF, and 6860 M -1 cm -1 for PTI-LiBr, Figure ), and they are one to two magnitudes lower than the absorption coefficients of molecular species without a forbidden HOMO-LUMO transition. Comparing PTI-LiBr and PTI-IF, removal of intercalated ions induces a significant blue shift of the absorption onset by 0.3 eV (from 3.2 eV in PTI-LiBr to 3.5 eV in PTI-IF), as seen in the Tauc plot (Figure ). This increase of the optical gap is also presentbut less apparent EELS band is likely a result of beam damage as it grows in intensity during the measurement.