Figure 6: Representation of the processes described earlier for molecular donor-acceptor systems [51]: charge separation leads to a charge transfer state; geminate charge recombination to the triplet state can occur through proton hyperfine interactions (H-HFI-ISC) and through spin-orbit charge transfer intersystem crossing (SOCT-ISC). The energy difference of the singlet and triplet charge transfer state is twice the exchange integral (J). See Figure 7 for application of these aspects to non-geminate charge recombination in polymer blends.