Atomic-Scale Insights Into Antisite-Defect-Induced Metallicity in Halide Perovskites

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Defects are inherent in halide perovskites, significantly influencing their stability and optoelectronic properties.
• Understanding defects at the atomic level is vital for advancing perovskite-based optoelectronic device performance.

Purpose of the Study:

• To directly visualize and characterize the atomic structure of the Pb_Cs antisite defect in CsPbBr₃ perovskite.
• To elucidate the impact of the Pb_Cs antisite defect on local structure, polarization, and electronic band structure.

Main Methods:

• Aberration-corrected scanning transmission electron microscopy (STEM) for direct atomic imaging.
• First-principles calculations to investigate defect-induced electronic structure modifications.

Main Results:

• Direct visualization of the Pb_Cs antisite defect in CsPbBr₃.
• Observed shortening of Pb─Pb bond length (~20 pm), local polarization, and ~3% compressive strain around the defect.
• Calculations showed the defect induces a semiconductor-to-metal transition by shifting the Fermi level into the conduction band.

Conclusions:

• Established a link between the atomic-scale structure of antisite defects, local polarization, and electronic structure modulation.
• Provided fundamental insights into defect engineering for enhancing the stability and efficiency of perovskite optoelectronic devices.