Eq. 11 is not strictly valid for all realistic polymers which are semiflexible rather than rigid or in case the interchain hopping frequency is comparable to the intra-chain counterpart (e.g., for short polymer chains) but can be used as an initial guide to correlate intra-chain mobility with the experimentally measured mobility. More complicated analytical relationships between charge diffusivity and polymer geometric structure could be introduced and they reveal that the motion becomes more sub-diffusive as the chain flexibility increases and the inter-chain hopping become more important for very flexible (or very short) chains. 21