Ternary Organic Solar Cells: Third-component Effect on Molecular Packing and Charge Transfer Properties

Abstract

Besides conventional photovoltaic properties, molecular engineering plays an important role in enhancing the synergy among components and maximizing the performance of ternary organic solar cells (TOSCs). Here, molecular dynamics simulations and long-range corrected density functional theory calculations are combined to examine the impact of several third-component structures on molecular packing and charge transfer properties in PM6:X:Y6 blends. SN exhibits superior miscibility in PM6:Y6 blend and forms an alloy-like structure with Y6, effectively promoting the formation of dimer/trimer donor-acceptor complexes. This contributes to the significant enhancement of exciton dissociation and reduction of non-radiative voltage losses (ΔV_nr). Meanwhile, electron delocalization on the SN_Y6 alloy modulates the LUMO levels of the trimer complexes, lowers exciton binding energy, and contributes to a further reduction of non-radiative recombination. However, other third-component structures exhibit modest efficiency in optimizing donor-acceptor mixing, leading to inefficient dimer/trimer complex formation, limited contribution to exciton dissociation enhancement, and a restricted ability to reduce ΔV_nr. This work provides valuable insights for the rational selection of third-component materials to enhance the performance of TOSCs.