Wang Yutong, Long Run
College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , P. R. China.
J Phys Chem Lett. 2020 Feb 20;11(4):1601-1608. doi: 10.1021/acs.jpclett.0c00139. Epub 2020 Feb 12.
Using time-domain density functional theory combined with nonadiabatic molecular dynamics, we have investigated the effect of light-induced lattice expansion on the nonradiative electron-hole recombination in the mixed-cation perovskite FAMAPbI. We demonstrate that charge carrier lifetime extends by a factor of 1.5 within 1% lattice expansion; the bandgap grows only by 0.04 eV; the electron-phonon coupling increases by 13%; and the decoherence time shortens by 37%. The small bandgap change has negligible influence on recombination times. Lattice expansion enhances atomic fluctuations that lead to the enhancement of electron-phonon coupling and acceleration of decoherence. By creating several high-frequency phonon modes, the lattice expansion shortens the decoherence time further. As a result, rapid decoherence beats an enhanced electron-phonon coupling, playing the dominant role in suppressing the nonradiative electron-hole recombination. The light-induced lattice expansion or strain effects provide a rational route to improve the perovskite photovoltaic and photoelectronic device performance.
我们采用时域密度泛函理论结合非绝热分子动力学，研究了光致晶格膨胀对混合阳离子钙钛矿FAMAPbI中非辐射电子 - 空穴复合的影响。我们证明，在晶格膨胀1%的范围内，电荷载流子寿命延长了1.5倍；带隙仅增加0.04 eV；电子 - 声子耦合增加了13%；退相干时间缩短了37%。小的带隙变化对复合时间的影响可忽略不计。晶格膨胀增强了原子涨落，导致电子 - 声子耦合增强和退相干加速。通过产生几种高频声子模式，晶格膨胀进一步缩短了退相干时间。结果，快速的退相干胜过增强的电子 - 声子耦合，在抑制非辐射电子 - 空穴复合中起主导作用。光致晶格膨胀或应变效应为改善钙钛矿光伏和光电器件性能提供了一条合理途径。
