Electrostatic Harmonization for Superior Charge Extraction at Interface for Stable High-Efficiency FAPbI Quantum Dots Solar Cells.

Organic-inorganic formamidinium lead triiodide (FAPbI) hybrid perovskite quantum dots (QDs) have garnered considerable attention in the photovoltaic field due to their narrow bandgap, exceptional environmental stability, and prolonged carrier lifetime. Unfortunately, their insulating ligands and surface vacancy defects pose significant obstacles to efficient charge transfer across device interfaces. In this work, an electrostatic harmonization strategy at the interface using a donor-acceptor dipole molecular attachment to achieve enhanced charge separation capabilities on the QD surface is ventured. On the basis of theoretical study and experimental evaluation, it has gained a comprehensive understanding of dipole-induced electronic restructuring at the quantum dot interfaces. It reveals that 3-fluoro-4-iodopyridine as a dipole source with appropriate energy levels and a high dipole moment effectively fills surface iodine vacancies (V), leading to rapid separation of photoexcited charge carriers. Particularly enhanced hole mobility and hydrophobicity are achieved through strong electronegative effects of fluorine and iodine. Consequently, the FAPbI QD solar cells achieve a power conversion efficiency as high as 14.11% with exceptional long-term stability in ambient. These perceptions provide effective interface engineering means for the hybrid perovskite QDs to advance their potential in high-performance optoelectronic applications.