Interfacial Bidirectional Anchoring for CsPbI₃ Phase Stabilization in Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Cesium lead iodide (CsPbI3) perovskites are promising for solar cells but suffer from phase instability.
• The black photovoltaic phase transforms into a yellow non-photovoltaic phase, especially under heat, due to Cs+ ion displacement and [PbI6]4- octahedra tilting.

Purpose of the Study:

• To develop a strategy for stabilizing the black CsPbI3 phase.
• To enhance the performance and durability of CsPbI3-based perovskite solar cells (PSCs).

Main Methods:

• Introduced 1-Methyl-3-(3-sulfopropyl)-1H-imidazol-3-ium chloride (SMCl) for a bidirectional anchoring strategy.
• Utilized SMCl's sulfonate group to bind Cs+ ions and its imidazole group to coordinate with [PbI6]4- octahedra.
• Investigated the effect of SMCl on CsPbI3 film strain and phase stability.

Main Results:

• SMCl effectively inhibited Cs+ displacement and [PbI6]4- tilting, stabilizing the black CsPbI3 phase.
• SMCl introduction induced compressive strain in the CsPbI3 film, further enhancing phase stability.
• Inverted PSCs utilizing SMCl achieved a high power conversion efficiency of 21.17% and demonstrated excellent operational stability.

Conclusions:

• The bidirectional anchoring strategy with SMCl is highly effective in stabilizing the black CsPbI3 phase.
• SMCl-treated CsPbI3 PSCs exhibit superior efficiency and long-term operational stability under demanding conditions (1000 hours, 65°C).
• This approach offers a promising pathway for developing durable and efficient perovskite solar cells.