Ferroelectric Alignment of Organic Cations Inhibits Nonradiative Electron–Hole Recombination in Hybrid Perovskites: Ab Initio Nonadiabatic Molecular Dynamics

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• 作者：Joanna Jankowska ; Oleg V. Prezhdo
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：February 16, 2017
• 年：2017
• 卷：8
• 期：4
• 页码：812-818
• 全文大小：464K
• ISSN：1948-7185

文摘

Hybrid organic–inorganic perovskites show impressive potential for photovoltaic applications and currently give rise to one of the most vibrant research areas in the field. Until recently, the electrostatic interactions between their organic and inorganic components were considered mostly for stabilization of the fragile perovskite structure. We study the effect of local interactions of polar C–N bonds in the organic layer on the nonradiative electron–hole recombination in the recently reported room-temperature ferroelectric hybrid perovskite, (benzylammonium)₂PbCl₄. Using nonadiabatic molecular dynamics and real-time time-dependent density functional theory, we show that ferroelectric alignment of the polar groups weakens the electron–phonon nonadiabatic coupling and inhibits the nonradiative charge recombination. The effect is attributed to suppression of contributions of higher frequency phonons to the electron–phonon coupling. The coupling is dominated in the ferroelectric phase by slower collective motions. We also demonstrate the importance of van der Waals interactions for the charge-phonon relaxation in the hybrid perovskite systems. Combined with the long-range charge separation achievable in the ferroelectric phase, the weakened electron–phonon coupling indicates that ferroelectric order in hybrid perovskites can lead to increased excited-state lifetimes and improved solar energy conversion performance.