Energetics and Kinetics Requirements for Organic Solar Cells to Break the 20% Power Conversion Efficiency Barrier

The thermodynamic limit for the efficiency of solar cells is predominantly defined by energy band gap used semiconductor. In case organic cells, both energetics and kinetics three different species play a role: excitons, charge transfer (CT) states, charge-separated states. this work, we clarify effect relative these species. Making use detailed balance, develop an analytical framework describing how intricate interplay between influences photocurrent generation, recombination, open-circuit voltage in cells. We essential requirements equilibrium among CT carriers to occur. Furthermore, find that photovoltaic parameters are determined not only states but also kinetic rate constants, highlighting importance slow exciton recombination at low energetic offsets. Finally, depending on parameters, optimal power conversion exceeding 20% offsets around 0.1 eV. These findings provide vital insights into operation state-of-art non-fullerene with