Highly Efficient and Stable Inverted Perovskite Solar Cell Using Pure δ-FAPbI₃ Single Crystals

Area of Science:

• Materials Science
• Renewable Energy
• Crystallography

Background:

• Perovskite solar cells (PSCs) offer promising photovoltaic performance.
• Achieving high efficiency and long-term stability in PSCs remains a critical challenge.
• Controlling crystal purity and minimizing defects are essential for device performance.

Purpose of the Study:

• To develop a novel method for synthesizing pure formamidinium lead triiodide (FAPbI3) single crystals.
• To fabricate highly efficient and stable inverted PSCs using these pure FAPbI3 crystals.
• To evaluate the power conversion efficiency (PCE) and long-term stability of the fabricated PSCs.

Main Methods:

• A new liquid phase reaction and antisolvent crystallization method was employed to synthesize pure δ-FAPbI3 single crystals.
• Molecular recognition at the crystal growth site prevented impurity incorporation.
• Fabrication of inverted PSCs using pure α-FAPbI3 crystals, with some devices surface-treated with 3-(aminomethyl)pyridine.

Main Results:

• The pure FAPbI3 crystals led to PSCs with significantly reduced trap-states and improved PCE.
• The champion device achieved a PCE of 23.48% under 1-Sun conditions.
• Surface-treated devices reached a PCE of 25.07%, and an unencapsulated device retained 97.22% of its initial efficiency after 1,000 hours of continuous operation at 85°C.

Conclusions:

• The developed method successfully produces high-purity FAPbI3 single crystals, crucial for high-performance PSCs.
• The fabricated PSCs demonstrate excellent power conversion efficiency and remarkable long-term thermal and photo stability.
• This work provides a pathway for developing next-generation, stable, and efficient perovskite solar cells.