Interfacial ferroelectricity unlocks stable formamidinium-based perovskites.

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Formamidinium (FA)-based perovskites are promising for solar cells but suffer from phase instability.
• Achieving long-term stability in FA-based perovskites is a significant challenge for their commercialization.

Purpose of the Study:

• To develop a strategy for enhancing the phase stability and performance of FA-based perovskites.
• To investigate the impact of interfacial ferroelectricity on perovskite structure and ion dynamics.

Main Methods:

• Integration of ferroelectric Cesium Manganese Bromide (CsMnBr3) nanocrystals (NCs) into FA-based perovskites.
• Utilizing the generated ferroelectric field to promote cation ordering and modulate the perovskite lattice.
• Assessing structural stability and ion migration barriers through advanced characterization.

Main Results:

• Ferroelectric NCs improved FA+ cation ordering and perovskite lattice regulation.
• Increased kinetic barriers for octahedral transformation and suppressed ion migration.
• Perovskite solar cell (PSC) minimodules retained 99% efficiency after 1000 hours under harsh conditions (85% RH, 85 °C).
• Achieved certified PSC efficiency of 26.40% and minimodule efficiency of 23.23%.

Conclusions:

• Interfacial ferroelectric engineering is an effective approach to achieve stable and high-performance FA-based perovskites.
• This method significantly enhances the operational lifetime and efficiency of perovskite solar cells.
• The findings pave the way for robust perovskite optoelectronic devices.