Amplifying the Performance and Stability of Perovskite Solar Cells Using Fluorinated Salt as the Surface Passivator

Abstract

The 3D‐halide perovskite‐based solar cells have shown outstanding power conversion efficiency, while the layered perovskite is emerging as the advanced version to deliver high stability. Galvanized with the surge of the report of layered perovskites, a common salt tetra‐n‐butyl ammonium hexafluorophosphate (TBAPF) as a passivating agent between perovskite and hole transporting layer that improves the power conversion efficiency and stability, is explored. The use of TBAPF as a surface passivator mitigates the surface defects and increases hydrophobicity. The fluorine atoms in TBAPF provide hydrogen bonding interaction with the hydrogen of organic ammonium cation in perovskite established by proton nuclear magnetic resonance techniques. Effective charge extraction to the hole transport layer is suggested by steady‐state photoluminescence measurements, showing higher quenching with the passivated perovskite compared to the pristine perovskite. The results suggest that TBAPF treatment improves the junction quality and minimizes the defects by virtue of H bonding, which in turn improves the photovoltaic parameters and long‐term stability.