Low-energy pathways lead to self-healing defects in CsPbBr₃

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Metal halide perovskites exhibit remarkable defect tolerance, crucial for solar cell applications.
• Schottky defect formation is theorized to drive self-regulation of charge carriers in these materials.

Purpose of the Study:

• Investigate atomic-level mechanisms of defect diffusion and recombination in CsPbBr3.
• Determine activation energies for Schottky pairs (interstitials and vacancies).
• Understand defect self-regulation for enhanced perovskite solar cell efficiency.

Main Methods:

• Utilized nudged elastic band calculations.
• Employed ab initio-derived pseudopotentials within quantum ESPRESSO.
• Calculated defect formation and migration energies.

Main Results:

• Identified interstitial defect pathways with activation energies at or below the experimental 0.53 eV.
• Uncovered a low-energy interstitial diffusion pathway via a "domino effect" mechanism.
• Demonstrated enhanced interstitial diffusion over longer distances.

Conclusions:

• The "domino effect" pathway facilitates rapid interstitial diffusion, contributing to defect self-healing.
• Findings suggest strategies to promote defect self-healing in perovskite materials.
• Provides insights into optimizing CsPbBr3 for high-efficiency solar cells.