Dependence of Electron–Hole Recombination Rates on Charge Carrier Concentration: A Case Study of Nonadiabatic Molecular Dynamics in Graphitic Carbon Nitride Monolayers
Dependence of Electron–Hole Recombination Rates on Charge Carrier Concentration: A Case Study of Nonadiabatic Molecular Dynamics in Graphitic Carbon Nitride Monolayers
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DOI：
10.1021/acs.jpcc.3c00211
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
Mohammad Shakiba;A. Akimov
中科院分区：
文献类型：
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作者：
Mohammad Shakiba;A. Akimov
通过在原型石墨氮化碳（C3N4）单层中进行系统的非绝热分子动力学（NA-MD）计算，我们证明了电子-空穴复合时间尺度对模拟超级电池的尺寸以及电荷载流子的形式浓度的强烈依赖性。使用我们最近开发的 NA-MD 方法和扩展的紧束缚电子结构计算，我们已经能够在包含多达 5600 个原子的 C3N4 单层中进行此类计算。预测的时间尺度从最小 (2 × 2) 系统中的 7 ps 到最大 (8 × 8、10 × 10) 系统中的 23 ns，并且取决于 NA-MD 方法和所使用的电子激励的基础。只有在非常大的系统中，例如 8 × 8 或 10 × 10 超级电池，浓度依赖性才可以忽略不计。在此限制下，时间尺度对 NA-MD 计算中使用的电子激发数量以及退相干效应也变得不敏感。我们提出了一个有效的状态简化模型来解释这个结果。
Through systematic nonadiabatic molecular dynamics (NA-MD) calculations in a prototypical graphitic carbon nitride (C3N4) monolayer, we demonstrate a strong dependence of electron–hole recombination time scales on the size of the simulation supercell and hence on the formal concentration of charge carriers. Using our recently developed NA-MD methodology with extended tight-binding electronic structure calculations, we have been able to conduct such calculations in C3N4monolayers containing up to 5600 atoms. The predicted time scales vary from 7 ps in the smallest (2 × 2) systems to 23 ns in the largest (8 × 8, 10 × 10) ones and depend on the NA-MD methodology and the basis of electronic excitations used. The concentration dependence becomes negligible only in very large systems, such as 8 × 8 or 10 × 10 supercells. In this limit, the time scales also become insensitive to the number of electronic excitations used in NA-MD calculations and to the inclusion of decoherence effects. We propose an effective state reduction model to explain this result.