Yavuz Ilhan, Lopez Steven A
Department of Physics, Marmara University, 34722, Ziverbey, Istanbul, Turkey.
Department of Chemistry and Chemical Biology, 12 Oxford Street, Harvard University, Cambridge, MA 02138, USA.
Phys Chem Chem Phys. 2016 Dec 21;19(1):231-236. doi: 10.1039/c6cp06431k.
The effect of short-range order and dispersivity on charge-transport for organic crystalline semiconductors are important and unresolved questions. This exploration is the first to discern the role of short-range order on charge-transport for crystalline organic semiconductors. A multimode computational approach (including Molecular Dynamics and kinetic Monte Carlo simulations) is employed to understand the hole mobility dispersivity of crystalline organic semiconductors. Crystalline organic solids feature a mesoscale region where dispersive charge-transport dominates; our calculations show a clear transition of charge-mobility from non-dispersive to dispersive. An empirical relationship between the dispersive and non-dispersive transport transition region and ideal simulation box thickness is put forth. The dispersive to non-dispersive transition region occurs when energetic disorder approaches 72 meV. Non-dispersive transport is observed for simulation box sizes greater than 3.7 nm, which corresponds to approximately 12 π-stacked layers in typical π-stacked organic solids. A qualitative relationship is deduced between the variability of measured dispersive hole and variability of computed dispersive hole mobilities and system size. This relationship will guide future charge-transport investigations of condensed-phase organic systems.
短程有序和分散性对有机晶体半导体电荷传输的影响是重要且尚未解决的问题。本研究首次探讨了短程有序在晶体有机半导体电荷传输中的作用。采用多模式计算方法（包括分子动力学和动力学蒙特卡罗模拟）来理解晶体有机半导体的空穴迁移率分散性。晶体有机固体具有一个中尺度区域，其中分散性电荷传输占主导；我们的计算表明电荷迁移率从非分散性到分散性有明显转变。提出了分散性和非分散性传输过渡区域与理想模拟盒厚度之间的经验关系。当能量无序接近72毫电子伏时，会出现从分散性到非分散性的转变区域。对于尺寸大于3.7纳米的模拟盒，观察到非分散性传输，这在典型的π堆积有机固体中大约对应12个π堆积层。推导出了测量的分散性空穴变异性与计算的分散性空穴迁移率变异性和系统尺寸之间的定性关系。这种关系将指导未来对凝聚相有机系统的电荷传输研究。
