Thermodynamically stabilized β-CsPbI₃-based perovskite solar cells with efficiencies >18

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Beta-Cesium Lead Iodide (β-CsPbI3) possesses a favorable bandgap for tandem solar cells.
• Experimental deposition and stabilization of β-CsPbI3 films present significant challenges.

Purpose of the Study:

• To develop a method for obtaining highly crystalline β-CsPbI3 films with enhanced phase stability.
• To improve the performance and reliability of β-CsPbI3 based perovskite solar cells.

Main Methods:

• Fabrication of β-CsPbI3 films.
• Synchrotron-based X-ray scattering for structural analysis.
• Elemental analysis using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS).
• Surface treatment with choline iodide.

Main Results:

• Highly crystalline β-CsPbI3 films with extended spectral response and enhanced phase stability were obtained.
• Synchrotron X-ray scattering confirmed highly oriented β-CsPbI3 grains.
• Elemental analyses confirmed the all-inorganic composition.
• Choline iodide surface treatment mitigated film defects, improved charge-carrier lifetime, and optimized energy-level alignment.
• Perovskite solar cells achieved reproducible and stable efficiencies of 18.4% under elevated ambient conditions (45 ± 5°C).

Conclusions:

• The developed method enables the production of stable and efficient β-CsPbI3 perovskite solar cells.
• Surface treatment with choline iodide is a viable strategy to enhance perovskite solar cell performance and stability.
• The findings contribute to the advancement of all-inorganic perovskite solar cell technology for practical applications.