What is special about these nanofibers? Photothermal deflection spectroscopy and time-resolved photoluminescence data indicate that they feature a particularly low energetic disorder, as measured by an Urbach tail (of meV) comparable to the room-temperature thermal energy . This static disorder is accounted for in our simulations using a Gaussian disorder model with the standard deviation . To explore the influence of energetic disorder, we have repeated the surface hopping simulations after multiplying (dividing) the reference value of by a factor two, which leads to a decrease (increase) in by about 50%, Figure . While this is expected based on the reduced (increased) availability of the spatially extended excitonic states in a transient delocalization regime (see Supplemental Figure ), it does not explain the diffusion coefficient measured in conventional regioregular P3HT thin films (with cm 2 /s for an Urbach energy of meV) , which is orders of magnitude lower.