Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA.
Department of Chemistry, University of Kentucky, Lexington, KY, 40506, USA.
Adv Mater. 2017 Jun;29(23). doi: 10.1002/adma.201700048. Epub 2017 Apr 12.
In order to understand how additives influence the structure and electrical properties of active layers in thin-film devices, a compositionally identical but structurally different guest-host system based on the syn and anti isomers of triethylsilylethynyl anthradithiophene (TES ADT) is systematically explored. The mobility of organic thin-film transistors (OTFTs) comprising anti TES ADT drops with the addition of only 0.01% of the syn isomer and is pinned at the mobility of OTFTs having pure syn isomer after the addition of only 10% of the isomer. As the syn isomer fraction increases, intermolecular repulsion increases, resulting in a decrease in the unit-cell density and concomitant disordering of the charge-transport pathway. This molecular disorder leads to an increase in charge trapping, causing the mobility of OTFTs to drop with increasing syn-isomer concentration. Since charge transport is sensitive to even minute fractions of molecular disorder, this work emphasizes the importance of prioritizing structural compatibility when choosing material pairs for guest-host systems.
为了了解添加剂如何影响薄膜器件中活性层的结构和电学性能，我们系统地研究了基于三乙基硅基乙炔基蒽并噻二噻吩（TES ADT）顺式和反式异构体的组成相同但结构不同的客体-主体体系。包含反式 TES ADT 的有机薄膜晶体管（OTFT）的迁移率随着仅添加 0.01%顺式异构体而下降，并且在添加仅 10%异构体后，OTFT 的迁移率被固定在具有纯顺式异构体的 OTFT 的迁移率。随着顺式异构体分数的增加，分子间斥力增加，导致单位晶胞密度降低，电荷传输途径无序。这种分子无序导致电荷捕获增加，从而导致 OTFT 的迁移率随着顺式异构体浓度的增加而下降。由于电荷输运对分子无序的微小分数都很敏感，因此这项工作强调了在为客体-主体体系选择材料对时优先考虑结构兼容性的重要性。
