Impact of Nanoscale Morphology on Charge Carrier Delocalization and Mobility in an Organic Semiconductor,Advanced Materials

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Impact of Nanoscale Morphology on Charge Carrier Delocalization and Mobility in an Organic Semiconductor
Advanced Materials ( IF 27.4 ) Pub Date : 2021-09-23 , DOI: 10.1002/adma.202104852
Matthew Ellis ₁ , Hui Yang ₁ , Samuele Giannini ₁ , Orestis G Ziogos ₁ , Jochen Blumberger ₁

Affiliation

A central challenge of organic semiconductor research is to make cheap, disordered materials that exhibit high electrical conductivity. Unfortunately, this endeavor is hampered by the poor fundamental understanding of the relationship between molecular packing structure and charge carrier mobility. Here a novel computational methodology is presented that fills this gap. Using a melt-quench procedure it is shown that amorphous pentacene spontaneously self-assembles to nanocrystalline structures that, at long quench times, form the characteristic herringbone layer of the single crystal. Quantum dynamical simulations of electron hole transport show a clear correlation between the crystallinity of the sample, the quantum delocalization, and the mobility of the charge carrier. Surprisingly, the long-held belief that charge carriers form relatively localized polarons in disordered OS is only valid for fully amorphous structures—for nanocrystalline and crystalline samples, significant charge carrier delocalization over several nanometers occurs that underpins their improved conductivities. The good agreement with experimentally available data makes the presented methodology a robust computational tool for the predictive engineering of disordered organic materials.

中文翻译：

纳米级形态对有机半导体中载流子离域和迁移率的影响

有机半导体研究的一个核心挑战是制造具有高导电性的廉价无序材料。不幸的是，这一努力受到对分子堆积结构和电荷载流子迁移率之间关系的基本理解不足的阻碍。这里提出了一种新的计算方法来填补这一空白。使用熔体淬火程序表明，无定形并五苯自发自组装成纳米晶结构，在较长的淬火时间下，形成单晶的特征人字形层。电子空穴传输的量子动力学模拟显示样品的结晶度、量子离域和电荷载流子的迁移率之间存在明显的相关性。出奇，长期以来认为载流子在无序 OS 中形成相对局部极化子的观点仅适用于完全非晶结构——对于纳米晶体和晶体样品，在几个纳米范围内发生显着的载流子离域，这支持了它们改善的电导率。与实验可用数据的良好一致性使所提出的方法成为用于无序有机材料预测工程的强大计算工具。

更新日期：2021-11-09

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