Intermediate polaronic charge transport in organic crystals from a many-body first-principles approach

Predicting the electrical properties of organic molecular crystals (OMCs) is challenging due to their complex crystal structures and electron-phonon (e-ph) interactions. Charge transport in OMCs is conventionally categorized into two limiting regimes – band transport, characterized by weak e-ph interactions, and charge hopping due to localized polarons formed by strong e-ph interactions. However, between these two limiting cases there is a less well understood intermediate regime where polarons are present but transport does not occur via hopping. Here we show a many-body first-principles approach that can accurately predict the carrier mobility in OMCs in the intermediate regime and shed light on its microscopic origin. Our approach combines a finite-temperature cumulant method to describe strong e-ph interactions with Green-Kubo transport calculations. We apply this parameter-free framework to naphthalene crystal, demonstrating electron mobility predictions within a factor of 1.5–2 of experiment between 100–300 K. Our analysis reveals that electrons couple strongly with both inter- and intramolecular phonons in the intermediate regime, as evidenced by the formation of a broad polaron satellite peak in the electron spectral function and the failure of the Boltzmann transport equation (BTE). Our study advances quantitative modeling of charge transport in complex organic crystals. This dataset contains input and output files required to reproduce the BTE results presented in our work.

由于有机分子晶体（Organic Molecular Crystals, OMCs）复杂的晶体结构与电子-声子相互作用（electron-phonon, e-ph），精准预测其电学属性极具挑战。传统上，有机分子晶体中的电荷输运被划分为两类极限模式：一类为能带输运，以弱电子-声子相互作用为特征；另一类为电荷跳迁，源于强电子-声子相互作用所形成的局域极化子。然而，在这两种极限情形之间，存在一类尚未被充分阐释的中间输运模式：其中虽存在极化子，但电荷输运并非通过跳迁完成。本研究提出一种多体第一性原理方法，可精准预测中间输运模式下有机分子晶体的载流子迁移率，并阐明其微观起源。该方法将描述强电子-声子相互作用的有限温度累积量方法与格林-久保输运计算相结合。我们将这一无参数框架应用于萘晶体，结果显示在100~300 K温度区间内，预测的电子迁移率与实验值的比值介于1.5至2倍之间。分析表明，在中间输运模式中，电子与分子间、分子内声子均存在强耦合，这一结论可通过电子谱函数中宽化的极化子卫星峰的形成以及玻尔兹曼输运方程（Boltzmann transport equation, BTE）的失效得到验证。本研究推动了复杂有机晶体中电荷输运的定量建模工作。本数据集包含复现本文中玻尔兹曼输运方程结果所需的输入与输出文件。