Based on the fluorene units with a moderate electron density, PDI-coFluoMA-15% (DPFluoMA = 3 and DPSt = 18) showed slight emission redshifts ("em,film = ~650 nm) and higher PLQY (24%) compared to PDI-tetraPS (21% for DP20). This suggests that fluorene units have a similar impact on PDI emission as naphthalene units. On the other hand, PDI-coAntMAc, PDI-coAntMA, PDI-coPyMA, and PDI-coVPy showed significant quenching of the solid-state emission with "em,film redshifted to the near-infrared (NIR) region (672, 692, 710, and 795 nm, respectively) at their highest PAM feed (Figure ). These results suggest that the TSCT processes between these strong electron donors and PDI acceptor dominate the observed emission in the aggregate state, as also implied by the significantly reduced fluorescence lifetime of the polymer films (Figure , J; Table ).