Fluorinated Pseudo‐Halide Anion Enables >19% Efficiency and Durable Perovskite Quantum Dot Solar Cells

Abstract

Abstract Metal halide perovskite quantum dots (PQDs), like formamidinium lead triiodide (FAPbI 3 ), hold significant promise for next‐generation photovoltaics. Surface manipulation of PQDs has been extensively reported to be crucial to their photovoltaic performance due to the dynamic binding of capping long‐chain ligands. In this work, an efficient surface engineering strategy employing a multifunctional fluorinated pseudo‐halide anion ligand, hexafluorophosphate (PF 6 − ) is reported for achieving efficient FAPbI 3 PQD solar cells. Leveraging its coordination capability, large ionic radius (2.38 Å), and intrinsic hydrophobicity, PF 6 − simultaneously passivates iodide vacancies, minimizes inter‐dot spacing for enhanced electronic coupling, suppresses ion migration, and provides a hydrophobic barrier. By replacing oleate ligands with PF 6 − in FAPbI 3 PQDs, an unprecedented high efficiency of 19.01% (17.19% for a 1 cm 2 ‐sized device) is achieved, and enhanced storage and operational stability. These findings will provide insight into the design of robust surface structures and low‐trap‐states PQD films toward high‐efficiency and stable solar cells.