Diamine-Mediated Synergistic Engineering of Orientation and Interfacial Field of 3D/1D Heterojunctions for Efficient Perovskite Photovoltaics.

The performance of three-dimensional (3D) perovskite solar cells (PSCs) is predominantly limited by interfacial non-radiative recombination and instability. Although low-dimensional (LD) interlayers, particularly two-dimensional (2D) perovskites, are widely adopted for surface passivation, their heterogeneous n-values and quantum-well confinement often impede charge transport. One-dimensional (1D) perovskites offer a promising alternative due to their structural flexibility and superior passivation capabilities, yet their potential has been underexploited by challenges in controlled crystallization and ordered orientation. Here, we constructed a 3D/PDAI2/1D heterojunction through sequential deposition of propane-1,3-diammonium iodide (PDAI2) and 4-amidinopyridinium chloride (4APyCl). The pre-anchored PDAI2 not only provides field-effect passivation but also templates the subsequent vertical alignment of 1D Pb-I chains assembled with 4APyCl. This configuration establishes continuous out-of-plane charge transport channels, enabling effective surface defect passivation, favorable energy-level alignment, and enhanced interfacial carrier extraction. The resulting inverted PSCs achieved a champion power conversion efficiency of 25.8% and retained 85% of the initial performance after 1000 h of maximum power point tracking under 1-sun illumination. By demonstrating the critical role of molecular orchestration in LD interlayers, this work provides a blueprint for establishing structure-property relationships and guides the rational design of stable and efficient 3D/1D perovskite photovoltaics.