Understanding Energy Loss in Organic Solar Cells: Toward a New Efficiency Regime

Reducing energy and voltage loss is an imperative area of improvement for the design of organic solar cells (OSCs). Both in the context of charge generation and charge recombination, significant amounts of energy are lost even in state-of-the-art OSCs compared with their inorganic counterparts. Through a set of recent examples, however, we show that (1) charge generation can proceed with high quantum efficiency even in the absence of an offset energy at the donor-acceptor interface and (2) non-radiative charge recombination may be mitigated by considering systems with distinct properties of the interfacial charge-transfer state. To capitalize on these recent advances in understanding, we provide three actionable paths forward that aim to better identify, process, and characterize low energy loss systems: incorporating consistent and accurate measurements for energy levels, moving away from photoluminescence quenching, and exploring blends with reduced miscibility.S.M.M. and R.H.F. acknowledge support from the KAUST Competitive Research Grant Program (grant number 2275). N.A.R. and G.C.B. acknowledge support from the Department of the Navy, Office of Naval Research (award numbers N00014-14-1-0580 and N00014-16-1-25200)