Multiple B-site doping suppresses ion migration in halide perovskites

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• Lead halide perovskites are promising for photovoltaics and optoelectronics.
• Ion migration is a key factor limiting the long-term stability of these materials.

Purpose of the Study:

• To investigate the relationship between perovskite lattice dynamics and ion migration energy barriers.
• To identify effective strategies for enhancing perovskite stability through microstructural engineering.

Main Methods:

• First-principles calculations were employed to study lattice dynamics.
• Machine learning molecular dynamics simulations were used to analyze ion migration.
• B-site substitution effects were systematically investigated.

Main Results:

• B-site substitution, especially with alkaline-earth and lanthanide elements, strengthens lattice interactions and restrains octahedral oscillations.
• This substitution significantly increases iodine migration energy barriers, outperforming other doping strategies.
• The enhanced barrier correlates with the geometric factor μτ (tolerance-octahedral product).

Conclusions:

• B-site doping is a superior strategy for stabilizing perovskite lattices and suppressing ion migration.
• Co- and multiple-element B-site doping offer enhanced effectiveness in lattice stabilization.
• Experimental validation confirmed improved ambient stability and transport properties in Eu-Ca-doped perovskite single crystals, highlighting B-site engineering for stable perovskite devices.