How Lattice Strain Affects Nonradiative Recombination and Mobility in FAPbI₃

Area of Science:

• Materials Science
• Solid State Physics
• Photovoltaics

Background:

• Lattice strain in hybrid organic-inorganic halide perovskites (HOIPs) is crucial for solar cell efficiency and stability.
• Understanding strain's dynamic effects on charge carriers and light-induced strain is vital but incomplete.

Purpose of the Study:

• To investigate how lattice strain influences charge carrier dynamics and transport in HOIPs.
• To elucidate the mechanisms behind light-induced lattice strain in HOIPs.

Main Methods:

• Computational simulations were employed to model the effects of lattice strain.
• Analysis focused on electron cooling, mobility, and recombination rates under strain.

Main Results:

• A 1% compressive stress increased electron mobility by ~50% and delayed hot electron cooling.
• A 1% tensile stress reduced electron mobility by ~37% and accelerated cooling.
• Both compressive and tensile strains were found to accelerate electron-hole recombination.
• Strain modulates lattice vibrations and energy levels, influencing carrier dynamics.
• Photoinduced strain arises from Pb-I bond changes driven by electron-phonon interactions and anharmonicity.

Conclusions:

• Lattice strain significantly alters carrier dynamics and transport properties in HOIPs.
• Strain effects are linked to lattice vibrations and energy level shifts.
• Understanding photoinduced strain mechanisms is key for improving HOIP solar cell efficiency and stability.