Elsner Jan, Xu Yucheng, Goldberg Elliot D, Ivanovic Filip, Dines Aaron, Giannini Samuele, Sirringhaus Henning, Blumberger Jochen
Department of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, UK.
Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
Sci Adv. 2024 Oct 25;10(43):eadr1758. doi: 10.1126/sciadv.adr1758. Epub 2024 Oct 23.
Thermoelectric materials convert a temperature gradient into a voltage. This phenomenon is relatively well understood for inorganic materials but much less so for organic semiconductors (OSs). These materials present a challenge because the strong thermal fluctuations of electronic coupling between the molecules result in partially delocalized charge carriers that cannot be treated with traditional theories for thermoelectricity. Here, we develop a quantum dynamical simulation approach revealing in atomistic detail how the charge carrier wave function moves along a temperature gradient in an organic molecular crystal. We find that the wave function propagates from hot to cold in agreement with the experiment, and we obtain a Seebeck coefficient in good agreement with experimental measurements that are also reported in this work. Detailed analysis reveals that gradients in thermal electronic disorder play an important role in determining the magnitude of the Seebeck coefficient, opening unexplored avenues for the design of OSs with improved Seebeck coefficients.
热电材料将温度梯度转化为电压。这种现象在无机材料中已得到较好理解，但在有机半导体（OS）中却了解得少得多。这些材料带来了挑战，因为分子间电子耦合的强烈热涨落导致电荷载流子部分离域，而传统热电理论无法处理这种情况。在此，我们开发了一种量子动力学模拟方法，能在原子层面详细揭示电荷载流子波函数如何在有机分子晶体中沿温度梯度移动。我们发现波函数从热端向冷端传播，这与实验结果一致，并且我们得到的塞贝克系数与本工作中报道的实验测量值也吻合良好。详细分析表明，热电子无序梯度在确定塞贝克系数的大小方面起着重要作用，为设计具有更高塞贝克系数的有机半导体开辟了未被探索的途径。
