Defect-Dependent Nonradiative Carrier Recombination in Cesium Lead Halide Perovskite Quantum Dots: A Time-Domain Ab...

Area of Science:

• Materials Science
• Quantum Chemistry
• Solid State Physics

Background:

• All-inorganic metal halide perovskite quantum dots (QDs), like CsPbBr₃, offer high stability and optoelectronic potential.
• Defect-mediated nonradiative recombination currently limits the performance of these promising QDs.
• The precise microscopic mechanisms behind defect influence remain unclear.

Purpose of the Study:

• To elucidate the defect-dependent nonradiative recombination mechanisms in CsPbBr₃ QDs.
• To differentiate recombination pathways based on specific intrinsic defects.
• To provide insights for optimizing perovskite QD performance through defect engineering.

Main Methods:

• Nonadiabatic molecular dynamics simulations were employed.
• Analysis focused on intrinsic defects: Br vacancies (V_Br), Cs interstitials (Cs_i), and Pb_Br antisites.
• Investigated defect-induced lattice distortions and electron-vibrational coupling.

Main Results:

• Two recombination regimes were identified: coherence-dominated and lattice-coupled.
• Br vacancies (V_Br) caused minimal distortion and weak coupling, leading to moderate recombination.
• Cs interstitials (Cs_i) and Pb_Br antisites induced significant lattice deformation and strong coupling, resulting in rapid carrier recombination.

Conclusions:

• A mechanistic understanding of defect-influenced carrier loss in CsPbBr₃ QDs was established.
• The study highlights the distinct roles of different intrinsic defects in recombination processes.
• Findings offer crucial guidance for targeted defect engineering in perovskite nanomaterials.