Surface Engineering-Induced 2D/3D Interfacial Reconstruction for Stable Low-Light Perovskite Solar Cells

Interfacial defects and ion migration critically limit the efficiency and operational stability of perovskite solar cells (PSCs), particularly under low-light conditions where interfacial recombination dominates. Herein, a postsurface treatment using the secondary amine dibutylammonium bromide (DBABr) is introduced to induce controlled 2D/3D interfacial reconstruction through the formation of a thin quasi-two-dimensional perovskite layer on a three-dimensional absorber. This dimensionally reconstructed interface effectively passivates surface defects, suppresses ion migration, and improves energy-level alignment without hindering charge extraction while remaining compatible with both organic and inorganic hole-transport layers (HTL). Under standard one-sun illumination (AM 1.5G), DBABr-treated devices exhibit a significant enhancement in power conversion efficiency (PCE), increasing from 13.82% to 15.52% relative to the control. Furthermore, the reconstructed interface enables efficient indoor energy harvesting, delivering a PCE of 30.57% for 0.09 cm² active-area devices and improving the PCE from 25.64% to 27.77% for 1 cm² devices under 1000 lx LED illumination, demonstrating scalability across device areas. Benefiting from the combined effects of the hydrophobic 2D surface layer and the carbon electrode, the devices retain approximately 90% of their initial efficiency after 1000 h of operation under ambient conditions. These results establish interfacial dimensional reconstruction via secondary-amine surface engineering as an effective strategy to simultaneously enhance efficiency, low-light performance, and operational durability of carbon-based PSCs, contributing to sustainable photovoltaic technologies aligned with Sustainable Development Goal 7 (affordable and clean energy).