Pseudohalide BF₄^-doping in metal halide perovskites: a first-principles perspective

Area of Science:

• Materials Science
• Photovoltaics
• Solid-State Chemistry

Background:

• Metal halide perovskite solar cells show rapid efficiency gains but suffer from poor operational stability.
• Instability under environmental and operational stress hinders commercialization of perovskite photovoltaics.
• Pseudohalide doping, specifically with tetrafluoroborate (BF₄⁻), presents a promising approach to address these limitations.

Purpose of the Study:

• To systematically review recent advancements in BF₄⁻-doped perovskite solar cells.
• To integrate experimental findings with theoretical understanding of BF₄⁻ doping effects.
• To elucidate the fundamental mechanisms responsible for improved performance and stability.

Main Methods:

• Review of experimental studies on BF₄⁻-doped perovskites.
• First-principles theoretical calculations to understand doping mechanisms.
• Analysis of structural, optoelectronic, and stability data.

Main Results:

• BF₄⁻ doping modifies structural properties, enhances optoelectronic performance, and improves multidimensional stability.
• Key mechanisms include hydrogen bonding network reconstruction, lattice anharmonicity suppression, and defect passivation.
• Lattice anharmonicity suppression is identified as the core mechanism driving these improvements.

Conclusions:

• BF₄⁻ doping offers a viable strategy for enhancing perovskite solar cell efficiency and stability.
• Suppression of lattice anharmonicity is a fundamental principle for designing stable perovskite materials.
• This work provides insights and guidance for developing next-generation perovskite photovoltaic devices.