Study on the long time aging behavior of MAPbI₃: from experiment to first-principles simulation

Area of Science:

• Materials Science
• Solid-State Physics
• Renewable Energy

Background:

• Perovskite solar cells (PSCs) are promising renewable energy devices.
• The core functional layer, methylammonium lead iodide (CH₃NH₃PbI₃), suffers from poor long-term stability and environmental degradation.
• Understanding degradation mechanisms is crucial for commercialization.

Purpose of the Study:

• To investigate the degradation mechanisms of CH₃NH₃PbI₃ films.
• To correlate observed degradation with intrinsic material properties.
• To identify strategies for enhancing perovskite film stability.

Main Methods:

• Monitoring changes in phase construction, light absorption, and fluorescence quenching during aging.
• Utilizing first-principles simulations to study defect properties and ionic diffusion.
• Analyzing defect formation energies and ion diffusion activation energies.

Main Results:

• Degradation involves initial fluorescence quenching followed by phase decomposition.
• Deep-level defects (e.g., V_Pb, I_Pb) with low formation energies cause fluorescence quenching.
• Easy ion diffusion, exemplified by low iodine ion diffusion activation energy (0.286 eV), leads to phase decomposition.

Conclusions:

• Both defect passivation and prevention of ion diffusion are essential for stable perovskite films.
• Addressing intrinsic material limitations is key to improving PSC longevity.
• This study provides fundamental insights for designing more durable perovskite solar cells.