We have performed quantum chemistry calculations on both dyes 7 and 8. Ground state (S0) optimized geometries have been obtained at the DFT level (B3LYP/6-31+G (d,p)), whereas the first few excited states have been calculated relying on the time-dependent DFT (TD-DFT) approach (B3LYP/6-31+G (d,p)). All the calculations have been performed in the gas-phase using the Gaussian16 (Revision B.01) package. A fairly notable difference between the two molecules occurs already at the level of ground state geometry, with dye 7 being planar and EDPP 8 showing a bent geometry (≈160°, see Fig. in the SI). TD-DFT calculations show that in dyes 7 and 8 the bright, lowest, excited state S1 corresponds to a π-π* (HOMO→LUMO) transition, which involves two fluorenes and the DPP core, with almost no contribution coming from the nitro-groups (see Fig. ). The relevant oscillator strengths are high, ranging from 1.54 for dye 8 to 1.6 for EDPP 7. Steady-state absorption and emission spectra in Fig. correspond to transitions that mainly involve S1. On the other hand, in both dyes 7 and 8, the second singlet excited state S2 corresponds to a HOMO→LUMO+1 transition with a large involvement of the nitro-groups and a strong quadrupolar charge-transfer (CT) character (see Fig. ). As a result, S2 is optically dark and has no influence in the steady state spectra (see Fig. ). At the same time, due to being very close in energy to S1 in the Franck-Condon region, S2 is involved in the solvent-dependent non-radiative processes discussed in the previous section (Fig. )..