Enhancing High-Humidity Stability of CsPbI₃ Perovskite Solar Cells Through Strong Bidentate Ligand Coordination

Area of Science:

• Materials Science
• Renewable Energy

Background:

• Inorganic CsPbI3 perovskite solar cells (IPSCs) suffer from rapid degradation in humid environments, limiting their practical application.
• Developing strategies to enhance the stability of IPSCs under high humidity is crucial for their commercialization.

Purpose of the Study:

• To design a defect-passivation approach to improve the humidity resistance and stability of CsPbI3 perovskite solar cells.
• To investigate the efficacy of monodentate p-toluenesulfonyl hydrazide (TSH) and bidentate 2-amino-6-methoxybenzothiazole (AMBT) ligands for defect passivation.

Main Methods:

• Density-functional-theory (DFT) calculations to determine ligand binding energies.
• X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy to analyze coordination bonds.
• Fabrication and characterization of CsPbI3 perovskite solar cells with ligand surface modification.

Main Results:

• AMBT exhibited a significantly higher binding energy (-1.91 eV) to CsPbI3 compared to TSH (-0.98 eV), indicating stronger interaction.
• Surface modification with AMBT led to improved crystal perfection, reduced trap states, and extended carrier lifetime.
• The modified IPSCs achieved a maximum power conversion efficiency (PCE) of 18.52% with a high fill factor of 84.35%.
• Unencapsulated devices maintained their structure and 40% of initial efficiency for 10 days under 80% relative humidity.

Conclusions:

• The defect-passivation strategy using AMBT effectively enhances the humidity resistance of CsPbI3 perovskite solar cells.
• The study provides a promising approach for developing stable and moisture-independent CsPbI3 perovskite solar cells.