Highly Thermostable and Efficient Formamidinium-Based Low-Dimensional Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Solid-State Chemistry

Background:

• Traditional 2D metal halide perovskites often use methylammonium (MA), leading to poor photovoltaic performance and stability.
• The Ruddlesden-Popper type is common but limited by the thermal instability of MA molecules.

Purpose of the Study:

• To develop novel MA-free, low-dimensional perovskites for improved solar cell efficiency and stability.
• To investigate formamidinium (FA)-based 2D perovskites with propane-1,3-diammonium (PDA) as organic spacer cations.

Main Methods:

• Synthesized MA-free 2D perovskites with the general formula (PDA)(FA)_n-1 Pb_n I_3n+1.
• Utilized FACl additive to achieve well-oriented crystal grains in perovskite films.
• Employed grazing-incidence X-ray diffraction (GIXRD) to study the role of chloride (Cl).

Main Results:

• Achieved a record power conversion efficiency (PCE) of 13.8% for FA-based 2D perovskite solar cells using optimized (PDA)(FA)₃ Pb₄ I₁₃.
• Demonstrated significantly higher thermal stability for (PDA)(FA)₃ Pb₄ I₁₃ films and devices compared to MA-containing analogues.
• FACl additive facilitated the formation of well-oriented crystal grains, enhancing device performance.

Conclusions:

• MA-free FA-based 2D perovskites offer a promising alternative for efficient and stable solar cells.
• The use of PDA as a spacer cation and FA as the primary component enhances thermal resilience.
• This work sets a new benchmark for FA-based 2D perovskite solar cell technology.