We analyzed the obtained complex THz conductivity using the Drude-Smith model (DSM) that describes Drude-type transport of free charges impeded by spatial confinement with a second term including a localization parameter (Figure , b, Figure ). The phenomenological DSM gives an estimation of the density of charge carriers 𝑁, the scattering time 𝜏, and the localization parameter 𝑐, which lies between 0 and -1 that describes Drudetype transport and completely immobile charge carriers, respectively. The fitting parameters reveal a charge scattering time of 2.5 and 2.9 femtoseconds for PTI-LiBr and PTI-IF, respectively, and a localization parameter of <-0.999 for both (Figure ). The low scattering time as well as the localization parameter close to -1 imply a high degree of localization. Using the hole effective mass obtained from the DFT calculations (PTI-LiBr bulk meff=2.25, PTI-IF bulk meff=1.20), the carrier mobility in the nanoscale 𝜇 𝑇𝐻𝑧 and the effective mobility 𝜇 𝑒𝑓𝑓 can be calculated as described in the SI. The effective mobility of 10 - 3 -10 -4 cm 2 V -1 s -1 of PTI-LiBr and PTI-IF is in the range of the one found in amorphous organic semiconductors. The reasons for the low mobility is the absent conjugation along the imide bridge as well as the highly localized character of the valence states.