Enhancing charge carrier dynamics with an N-type polymer guest for printable ternary organic solar modules

The ternary strategy offers a promising route to enhance the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In this contribution, we focus on the state-of-the-art binary system PM6:L8-BO and reveal how the n-type polymer guest (PYIT) in the PM6:L8-BO:PYIT ternary system enhances carrier dynamics, thereby improving both efficiency and scalability for large-area printable OSC modules. These benefits are primarily attributed to two key factors: (i) the excellent miscibility of the PYIT guest with the host materials, coupled with the chain-dominant structure and high crystallinity nature of the PYIT polymer, which creates additional pathways for carrier transport and charge transfer; (ii) the incorporation of PYIT, which limits the excessive aggregation of L8-BO, improves molecular packing, and reduces film defects, thereby enhancing exciton dynamics. These optimizations lead to an increase in PCEs from 17.58% in the binary system to 18.59% in the ternary OSC, with improvements across all photovoltaic parameters. More importantly, the PM6:L8-BO:PYIT ternary system exhibits excellent compatibility with large-area printing processes, as demonstrated by a doctor blading OSC module achieving 15.57% PCE over an area of 11.7 cm2. This work highlights the potential of the ternary methodology in tuning the physical properties of OSCs while enhancing both performance and scalability.