Crossover from Hopping to Band-Like Charge Transport in an Organic Semiconductor Model: Atomistic Nonadiabatic Molecular Dynamics Simulation,The Journal of Physical Chemistry Letters

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Crossover from Hopping to Band-Like Charge Transport in an Organic Semiconductor Model: Atomistic Nonadiabatic Molecular Dynamics Simulation
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-05-22 00:00:00 , DOI: 10.1021/acs.jpclett.8b01112
Samuele Giannini ₁ , Antoine Carof ₁ , Jochen Blumberger _{1,

2}

Affiliation

The mechanism of charge transport (CT) in a 1D atomistic model of an organic semiconductor is investigated using surface hopping nonadiabatic molecular dynamics. The simulations benefit from a newly implemented state tracking algorithm that accounts for trivial surface crossings and from a projection algorithm that removes decoherence correction-induced artificial long-range charge transfer. The CT mechanism changes from slow hopping of a fully localized charge to fast diffusion of a polaron delocalized over several molecules as electronic coupling between the molecules exceeds the critical threshold V ≥ λ/2 (λ is the reorganization energy). With increasing temperature, the polaron becomes more localized and the mobility exhibits a “band-like” power law decay due to increased site energy and electronic coupling fluctuations (local and nonlocal electron–phonon coupling). Thus, reducing both types of electron–phonon coupling while retaining high mean electronic couplings should be part of the strategy toward discovery of new organics with high room-temperature mobilities.

中文翻译：

有机半导体模型中从跳跃跃迁到类似带电荷的传输：原子非绝热分子动力学模拟

使用表面跳跃非绝热分子动力学研究了有机半导体的一维原子模型中电荷传输（CT）的机理。该仿真得益于一种新实现的状态跟踪算法，该算法可解决微不足道的表面交叉问题，并得益于一种投影算法，该算法消除了退相干校正引起的人工远程电荷转移。当分子之间的电子耦合超过临界阈值V时，CT机制从完全局域电荷的缓慢跳变变为在多个分子上局域化的极化子的快速扩散≥λ/ 2（λ是重组能）。随着温度的升高，极化子变得更加局限，由于位能量增加和电子耦合波动（局部和非局部电子-声子耦合），迁移率表现出“带状”幂律衰减。因此，在保持高平均电子耦合的同时减少两种类型的电子-声子耦合应该是发现具有高室温迁移率的新有机物的策略的一部分。

更新日期：2018-05-22

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