Ferroelastic domains drive charge separation and suppress electron–hole recombination in all-inorganic halide perovskites: time-domain ab initio analysis

• Published in: Nanoscale horizons Vol. 5; no. 4; pp. 683 - 690
• Main Authors: Shi, Ran, Zhang, Zhaosheng, Fang, Wei-hai, Long, Run
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.04.2020
• Subjects: Broken symmetry; Carrier lifetime; Coupling (molecular); Current carriers; Density functional theory; Electrons; Molecular dynamics; Perovskites; Phonons; Time domain analysis; Wave functions
• ISSN: 2055-6756; 2055-6764; 2055-6764
• DOI: 10.1039/C9NH00717B

All-inorganic perovskites have great potential in photovoltaic applications and their performance is subject to phonon-assisted charge recombination dynamics. Local microstructures, such as ferroelastic domains, are considered to have a significant influence on the charge carrier lifetime in the CsPbBr 3 perovskite. Employing a combination of time-domain density functional theory and nonadiabatic (NA) molecular dynamics simulations, we demonstrate that the formation of ferroelastic domains weakens the NA coupling and suppresses the non-radiative electron–hole recombination. This effect originates from the ferroelastic domains separating electron and hole wave functions spatially and decreasing the NA coupling by a factor of 2.4 compared to pristine CsPbBr 3 , delaying electron–hole recombination by a factor of 4.2. We also show that symmetry breaking enhances electronic–vibrational interactions, activating more phonon modes and accelerating quantum decoherence by 1 fs or so, which further slows recombination. Both factors compete successfully with the slightly reduced bandgap of about 0.2 eV and prolong the charge carrier lifetime to several nanoseconds. Our study advances the understanding of the atomistic mechanism for inhibited recombination in the CsPbBr 3 perovskite in the presence of ferroelastic domains, providing an effective route to design high-performance all-inorganic halide perovskites.