Interfacial Coupling Design Enhancing Hole Transport in PTAA-Based Perovskite Solar Cells with Efficiency over 26%

Constructing 2D/3D perovskite heterojunction is an effective method to improve performance and stability of perovskite solar cells (PSCs), while the quantum well in 2D perovskites hinders carrier transport. To address this issue, π-conjugated semiconducting ligands have been introduced to enhance carrier-transfer capability of 2D perovskites. Here, two triphenylamine (TPA)-based ligands are specifically designed through π-extension with a fused (N-TPEAI) or covalently linked (P-TPEAI) benzene ring. For the first time, TPA semiconductor-based ligands have been incorporated to construct 2D/3D PSCs with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) as hole-transport materials (HTMs). Combined experimental and computational analyses reveal that this π-conjugation extension strategy proves to be effective in strengthening intermolecular interactions both between the adjacent spacer cations within 2D perovskites and at perovskite/PTAA interfaces, particularly in the case of P-TPEAI. Ultimately, the resultant 2D/3D PSCs employing P-TPEAI achieve an outstanding efficiency of 26.13%, which, to the best of our knowledge, is the highest value reported for 2D/3D PSCs incorporating PTAA HTMs. Moreover, benefiting from the robustness of both 2D perovskites and PTAA, the corresponding devices also exhibit excellent light-heat stability, meeting ISOS-L-2 protocol. These findings provide important guidelines for future design of organic spacers in advancing efficient and robust PSCs and related optoelectronic devices. © The Author(s) 2026.