Tuning perovskite recombination by hydrogen interstitial oxidation state

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• Nonradiative recombination is a major factor limiting perovskite solar cell efficiency.
• Hydrogen interstitial defects are known to influence charge carrier dynamics in perovskites.

Purpose of the Study:

• To investigate the role of hydrogen interstitial defect oxidation states on recombination dynamics in FAPbI3.
• To elucidate the atomistic mechanisms behind defect-induced recombination.
• To explore defect passivation strategies for enhancing perovskite performance.

Main Methods:

• Combined time-dependent density functional theory (TD-DFT) with nonadiabatic molecular dynamics (NAMD) simulations.
• Analyzed the impact of different hydrogen interstitial oxidation states (H0i, Hi+, Hi-) on recombination lifetimes.
• Investigated the effect of chlorine passivation (Cl@H0i) on defect properties and carrier dynamics.

Main Results:

• Recombination lifetime varied by three orders of magnitude depending on hydrogen interstitial oxidation state (0.1 ns for H0i, 44 ns for Hi+, 72 ns for Hi-).
• The neutral hydrogen interstitial (H0i) introduced a deep-level defect state, significantly increasing nonadiabatic coupling (0.35 meV to 1.56 meV).
• Chlorine passivation (Cl@H0i) neutralized H0i defects, reduced nonadiabatic coupling to 0.30 meV, and extended carrier lifetime to 87 ns.

Conclusions:

• The oxidation state of hydrogen interstitials critically governs nonradiative recombination in FAPbI3.
• Chlorine passivation is an effective strategy to mitigate recombination losses caused by H0i defects.
• Atomistic insights into defect dynamics are crucial for designing high-performance perovskite materials.