Enhanced Fill Factor and Efficiency of Ternary Organic Solar Cells by a New Asymmetric Non‐Fullerene Small Molecule Acceptor

Asymmetric non-fullerene small molecules acceptor (as-NF-SMAs) exhibit greater vitality in photovoltaic materials compared to their symmetric counterparts due to their larger dipole moments and stronger intermolecular interactions, which facilitate exciton dissociation and charge transmission in organic solar cells (OSCs). Here, we introduced a new as-NF-SMAs, named IDT-TNIC, as the third component in ternary organic solar cells (TOSCs). The asymmetric IDT-TNIC used indacenodithiophene (IDT) as the central core, alkylthio-thiophene as a unilateral π-bridge and extended end groups as electron-withdrawing. Due to the non-covalent conformational lock (NCL) established between O⋅⋅⋅S and S⋅⋅⋅S, the IDT-TNIC molecule preserves its coplanar structure effectively. Furthermore, IDT-TNIC exhibits complementary absorption and excellent compatibility with donor and acceptor materials, as well as optimized ladder energy level arrangement, resulting in a higher and more balanced μ