Wang Baotieliang, Xu Ting, Yu Bo, Zou Jiawei, Luan Shifang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin130022, P. R. China.
University of Science and Technology of China, Hefei, Anhui230026, P. R. China.
ACS Appl Mater Interfaces. 2023 Feb 8;15(5):7204-7216. doi: 10.1021/acsami.2c18495. Epub 2023 Jan 29.
Alkyl chain modification strategies in both organic semiconductors and inorganic dielectrics play a crucial role in improving the performance of organic thin-film transistors (OTFTs). Polyimide (PI) and its derivatives have received extensive attention as dielectrics for application in OTFTs because of flexibility, high-temperature resistance, and low cost. However, low-temperature solution processing PI-based gate dielectric for flexible OTFTs with high mobility, low operating voltage, and high operational stability remains an enormous challenge. Furthermore, even though di--decyldinaphtho[2,3-b:2',3'-f]thieno[3,2-]thiophene (C-DNTT) is known to have very high mobility as an air-stable and high-performance organic semiconductor, the C-DNTT-based TFTs on the PI gate dielectrics still showed relatively low mobility. Here, inspired by alkyl side chain engineering, we design and synthesize a series of PI materials with different alkyl side chain lengths and systematically investigate the PI surface properties and the evolution of organic semiconductor morphology deposited on PI surfaces during the variation of alkyl side chain lengths. It is found that the alkyl side chain length has a critical influence on the PI surface properties, as well as the grain size and molecular orientation of semiconductors. Good field-effect characteristics are obtained with high mobilities (up to 1.05 and 5.22 cm/Vs, which are some of the best values reported to date), relatively low operating voltage, hysteresis-free behavior, and high operational stability in OTFTs. These results suggest that the strategy of optimizing alkyl side-chain lengths opens up a new research avenue for tuning semiconductor growth to enable high mobility and outstanding operational stability of PI-based OTFTs.
有机半导体和无机电介质中的烷基链修饰策略在提高有机薄膜晶体管（OTFT）的性能方面起着至关重要的作用。聚酰亚胺（PI）及其衍生物因其柔韧性、耐高温性和低成本，作为用于OTFT的电介质受到了广泛关注。然而，用于具有高迁移率、低工作电压和高操作稳定性的柔性OTFT的低温溶液处理PI基栅极电介质仍然是一个巨大的挑战。此外，尽管已知二癸基二萘并[2,3-b:2',3'-f]噻吩并[3,2-b]噻吩（C-DNTT）作为一种空气稳定的高性能有机半导体具有非常高的迁移率，但基于PI栅极电介质的C-DNTT基TFTs仍然显示出相对较低的迁移率。在此，受烷基侧链工程的启发，我们设计并合成了一系列具有不同烷基侧链长度的PI材料，并系统地研究了PI表面性质以及在烷基侧链长度变化过程中沉积在PI表面的有机半导体形态的演变。研究发现，烷基侧链长度对PI表面性质以及半导体的晶粒尺寸和分子取向具有关键影响。在OTFTs中获得了良好的场效应特性，具有高迁移率（高达1.05和5.22 cm²/Vs，这是迄今为止报道的一些最佳值）、相对较低的工作电压、无滞后行为和高操作稳定性。这些结果表明，优化烷基侧链长度的策略为调节半导体生长开辟了一条新的研究途径，以实现基于PI的OTFTs的高迁移率和出色的操作稳定性。
