Tailoring Interlayer Spacers for Efficient and Stable Formamidinium-Based Low-Dimensional Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• 2D Dion-Jacobson (DJ) perovskite solar cells suffer from mediocre performance due to defective film quality.
• Rigid diammonium organic spacers cause lattice mismatches, leading to defects and poor optoelectronic properties.

Purpose of the Study:

• To improve the film quality of formamidinium (FA)-based low-dimensional perovskites.
• To enhance the performance and stability of 2D DJ perovskite solar cells through novel interlayer spacers.

Main Methods:

• Introduction of a secondary, flexible monovalent spacer cation into the perovskite structure.
• Fabrication and characterization of perovskite films with modified interlayer spacers.
• Optimization of the (PDA_0.9 PA_0.2 )(FA)₃ Pb₄ I₁₃ composition.

Main Results:

• Flexible monovalent spacers alleviate lattice distortions and reduce crystal defects.
• Improved film quality, desirable morphology, preferable crystal orientation, and reduced defect states were achieved.
• The optimized perovskite solar cell reached a power conversion efficiency of 16.0% and retained 90% efficiency after 800 h at 85 °C.

Conclusions:

• The flexible monovalent spacer strategy effectively enhances the quality and performance of 2D DJ perovskite films.
• This approach offers a pathway to high-efficiency and stable perovskite solar cells.
• The study demonstrates significant progress in overcoming limitations in 2D perovskite solar cell technology.