Fig. 4. The role of relative exciton delocalization length. (a) Calculated absolute (black) and relative (red) delocalization length as a function of polymer length (squares). Vertical lines indicate the studied polymers. Circles on the P11 line indicate the more and less disordered polymer variations of P11 studied in (b). (b) Calculated time dependence of the integrated fifth-order EEI2D signal for varying relative exciton delocalization. The effect is analogous to the varying length observed in Fig. 3. (c) Exemplary cartoon illustrating excitons with relative delocalization length of 9% (more disordered case, top) and 34% (more ordered case, bottom). The more delocalized excitons will meet and interact sooner after photoexcitation than the localized ones.