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

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Ferroelastic domains drive charge separation and suppress electron–hole recombination in all-inorganic halide perovskites: time-domain ab initio analysis
Nanoscale Horizons ( IF 8.0 ) Pub Date : 2019-12-23 , DOI: 10.1039/c9nh00717b
Ran Shi _{1,

2,

3,

4,

5} , Zhaosheng Zhang _{5,

6,

7,

8} , Wei-hai Fang _{1,

2,

3,

4,

5} , Run Long _{1,

2,

3,

4,

5}

Affiliation

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 CsPbBr₃ 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 CsPbBr₃, 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 CsPbBr₃ perovskite in the presence of ferroelastic domains, providing an effective route to design high-performance all-inorganic halide perovskites.

中文翻译：

铁弹性域驱动电荷分离并抑制全无机卤化物钙钛矿中的电子-空穴复合：时域从头算分析

全无机钙钛矿在光伏应用中具有巨大潜力，其性能受声子辅助电荷复合动力学的影响。诸如铁弹性域之类的局部微结构被认为对CsPbBr ₃钙钛矿中的载流子寿命有重大影响。结合时域密度泛函理论和非绝热（NA）分子动力学模拟，我们证明了铁弹性域的形成会削弱NA耦合并抑制非辐射电子-空穴复合。与原始CsPbBr ₃相比，此效应源自铁弹性域在空间上分隔电子和空穴波的功能并将NA耦合降低了2.4倍。，将电子-空穴复合延迟了4.2倍。我们还表明，对称性破坏增强了电子-振动相互作用，激活了更多的声子模式，并加速了1fs左右的量子退相干，从而进一步降低了重组速度。这两个因素都可以成功地与约0.2 eV的带隙略微降低进行竞争，并将电荷载流子寿命延长至几纳秒。我们的研究提高了在铁弹性域存在下CsPbBr ₃钙钛矿中抑制重组的原子机理的理解，为设计高性能全无机卤化物钙钛矿提供了有效途径。

更新日期：2019-12-23

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