Harnessing Strong Aromatic Conjugation in Low-Dimensional Perovskite Heterojunctions for High-Performance Photovoltaic Devices

Abstract The combination of three-dimensional (3D) metal halide perovskite with low-dimensional (LD) perovskite in a heterojunction has shown significant potential for improving the performance of perovskite solar cells (PSCs). However, the large organic cations in LD perovskite often introduces carrier mobility anisotropy and impedes charge transport at the heterojunction interface, thereby limiting the overall efficiency of PSCs. In this study, we report a novel LD/3D perovskite heterojunction that introduces strong aromatic conjugated (SAC) LD perovskite materials at the 3D perovskite/electron extraction interface in p-i-n PSCs to reduce the electron transport resistance crossing the interface. SAC molecules possess a large π conjugated network through aromatic rings connected by conjugated bonds. This network results in continuous energy band orbits between the [Pb2I6]2− framework and the organic cation, thereby effectively suppressing interfacial non-radiative recombination and enhancing carrier extraction efficiency. As a result, the fabricated PSCs exhibit significantly improved efficiency, reaching up to 25.66% (certified 25.20%). Furthermore, these devices demonstrate exceptional stability, maintaining over 95% of the initial efficiency after 1200 hours and 1000 hours under ISOS-L-1I and ISOS-D-1 protocols, respectively. The chemistry design of SAC molecules in the LD/3D perovskite heterojunction represents a promising strategy for developing efficient and stable PSCs, paving the way for further advancements in the field of PSC technology.