The understanding of photo-excited excitons (Coulomb bonded electron-hole pairs) in OPV is of major importance because their behavior dominates the materials' photophysics, including exciton migration and dissociation (charge separation of electron and hole). The low dielectric constant of OSCs leads to a comparably strong Coulomb interaction between the electron and hole and as a result to a low power conversion efficiency (PCE) with one of the highest reports of 18.66% for a non-fullerene acceptor in a ternary blend. A critical limiting factor for the efficiency of photo-excited devices is the exciton lifetime during which electron and hole recombine and the excited state relaxes back to the system's ground state. It has been shown that photo-excitation with higher energy than band-gap energy, generating so-called hot excitons, leads to higher efficiency of charge separation at the donor-acceptor interface via occupation of charge-transfer (CT) states (CT excitons). Theoretical description via non-adiabatic dynamics simulation were employed to gain further insight revealing the hot CT excitons to drive charge separation at the interface and a large energy gap between CT states and lower excitonic states to increase the exciton lifetime in molecular aggregates. Even without a donor-acceptor interface, free charge generation was reported and traced back to a spontaneous intramolecular splitting process in non-fullerene-acceptor Y6 or to an inter-moiety charge transfer exciton (i-EX) within the acceptor (or donor) aggregates. Similar to the i-EX state within an aggregate, an intramolecular charge transfer (ICT) state, or polaron-pair state, within one OSC chain/molecule is believed to favor subsequent charge separation due to a delocalized electron and hole wavefunction and thus lower Coulomb interaction correlating the charges. Such ICT states were found to be quickly occupied and to act as precursor for a charge separated state within < 200 fs. Such dynamics is favored by excitation of higher-lying excited states, rendering the ICT state more relevant in the early times of exciton generation. Moreover, the importance of a highly polarized state, i.e., a large electrical dipole moment, created by the exciton was found to indicate an easier charge separation because of a better separated electron and hole wavefunction and consequently weaker Coulomb interaction with the delocalization promoting charge separation. Recombination and charge separation processes are sensitive to the organic semiconductors structure. A promising route is to use donor-acceptor alternating polymers with their electron "push" and "pull" effects to promote spatially separated electron and hole wavefunctions, i.e., polarized ICT or polaron-pair states. Investigation of four similar donoracceptor polymers based on the CPDT-donor component by Tautz et al. revealed that acceptor units with higher electron affinity lead to higher initial polaron-pair state generation but also increased charge recombination (lower lifetime), whereas a π-spacer between both units leads to a decreased charge recombination probability (higher lifetime) while also lowering the initial polaron-pair generation probability, possibly due to a π-bridge planarization mechanism reported within 400 fs. The detailed understanding of general design rules to inhibit exciton recombination and thus enhance the efficiency of the charge separation process, however, is still somewhat limited.