Multifunctional DIPAI Surface Passivation: Enhancing Efficiency and Stability of Perovskite Solar Cells Across Lighting Conditions

Defect-mediated recombination remains a critical bottleneck for perovskite solar cells (PSCs), limiting both the efficiency and operational stability. Passivating these defects to suppress recombination is a crucial strategy for improving the performance of PSCs. Here, di-isopropylammonium iodide (DIPAI) was introduced as a multifunctional surface ligand that not only passivated defects and stabilized the perovskite phase but also fine-tuned energy-level alignment, facilitating efficient carrier transfer between the perovskite layer and the charge transport layers. The amino groups in DIPAI coordinate with uncoordinated Pb2+ions and organic cations, promoting secondary grain growth and suppressing nonradiative. As a result, DIPAI-treated PSCs show a significant PCE enhancement of 8.3%, from 13.35 to 14.46% under one-sun illumination, and a notable improvement in indoor performance from 28.25 to 29.65% under 1000 lx LED lighting, placing them among the top-performance mixed halide perovskite devices reported. Furthermore, the devices demonstrate excellent stability, maintaining 94% of their initial efficiency after 1000 h under humid conditions (30–35%RH). This work introduces a robust and scalable surface engineering strategy for defect suppression and stability enhancement, advancing the practical deployment of PSCs in both indoor and outdoor lighting environments.