In the NMe2-substituted push-pull compound discussed in Figure , the T1-T3 states are very close in energy to one another (T2-T1 < 0.01 eV, see Figure ). The energetic proximity of multiple states of different (delocalized and CT) character to the lower S1 state may provide efficient channels for reverse intersystem crossing. By contrast, in the more strongly polarized NPMe3-substituted compound, the CT-type T1 state is 0.25 eV below the next lowest triplet (see Figure ).