Impact of alloy-like phase on energy loss mitigation in multi-component organic photovoltaics

Abstract

The multi-component strategy has proven effective in advancing the performance of organic photovoltaics (OPVs), enhancing photocurrent and fill factor through spectral complementarity and morphology optimization. However, the open-circuit voltage (V_OC) mechanism in multi-component systems lacks systematic investigation. In this study, we explore the influence of alloy-like phases on energy level distribution and energy loss mechanisms in multi-component OPVs. Appropriate modulation of donor alloy-like phases maintains the original intermolecular stacking, enhances component compatibility, reduces acceptor aggregation, and improves acceptor phase purity, mitigating non-radiative recombination losses. Additionally, suitable alloy-like phase modulation elevates charge transfer (CT) states, reducing the gap between CT and local exciton state, lowering reorganization energy, and alleviating radiative recombination loss below the bandgap. Through synergistic optimization (layer-by-layer method with solid additive), ternary devices based on Y6 acceptor achieve a notable 19.41% power conversion efficiency, offering new insights for the analysis of the energy loss of the multi-component OPVs.