Based on the level scheme developed in Figure , also the possible electronic excitations can be qualitatively understood and categorized as illustrated in Figure . Compared to the charge neutral OSC, the formation of in-gap polaron states leads to new features also in the optical excitation spectrum. Among those excitations from occupied into unoccupied electronic orbitals that do not involve any significant charge transfer between molecular constituents of the complex, we call those excitations from HOMO-1 to LUMO+1 and higher interband excitations and label the corresponding spectral features as P1. Those starting in lower-lying occupied levels and ending in the in-gap polaron state, or LUMO, we call intraband excitations and label them with P2. In addition to the dominant polaron excitations discussed above and sketched in Figure (c), additional electronic excitations are possible between molecular entities in the complex that however show significant charge transfer character and thus carry relatively low oscillator strength.