Orthogonal Binary Cations Arrangement Homogenizing Interfacial Coordination and Electronic Landscapes for High Performance Perovskite Solar Cells

Abstract

Heterogeneous surface defects and non-uniform interfacial electronic landscapes constitute critical barriers to the efficiency and stability of perovskite solar cells. Here, we introduce an orthogonal binary cation (OrthBC) passivation strategy that forms parallel and perpendicular molecular orientations on the perovskite surface. Theoretical and experimental analyses confirm that this configuration simultaneously reinforces both ammonium-halide hydrogen bonding (2.55 Å, 143.5°) and cation–π interactions between Pb2+ and the phenyl unit (4.27 Å). The OrthBC approach enhances lattice coherence and optoelectronic uniformity while creating a homogeneous electronic landscape and a robust built-in electric field, which collectively minimize interfacial energy loss. Consequently, the champion device achieves a power conversion efficiency of 26.50% and demonstrates excellent operational stability, maintaining over 90% of its initial performance for more than 1000 hours under ISOS-D-2 and ISOS-L-2I aging protocols. The versatility and robustness of the OrthBC approach are further underscored by its scalability to 24.91% efficiency on a 1.00 cm2 device and its broad applicability, achieving 24.07% efficiency for a 1.68 eV wide-bandgap perovskite.