Acceptor Percolation Determines How Electron-Accepting Additives Modify Transport of Am bipolar Polymer Organic Field-Effect Transistors

作者：Ford, Michael J.^*; Wang, Ming; Bustillo, Karen C.; Yuan, Jianyu; Thuc-Quyen Nguyen; Bazan, Guillermo C.^*

来源：ACS Nano, 2018, 12(7): 7134-7140.

DOI：10.1021/acsnano.8b03006

• organic field-effect transistors
• ambipolar
• alternative acceptor
• morphology
• organic semiconductors
• polymer semiconductors

Organic field-effect transistors (OFETs) that utilize ambipolar polymer semiconductors can benefit from the ability of both electron and hole conduction, which is necessary for complementary circuits. However, simultaneous hole and electron transport in organic field-effect transistors result in poor ON/OFF ratios, limiting potential applications. Solution processing methods have been developed to control charge transport properties and transform ambipolar conduction to hole-only conduction. The electron-acceptor phenyl-C61-butyric acid methyl ester (PC61BM), when mixed in solution with an ambipolar semiconducting polymer, can reduce electron conduction. Unipolar p-type OFETs with high, well-defined ON/OFF ratios and without detrimental effects on hole conduction are achieved for a wide range of blend compositions, from 95:5 to 5:95 wt % semiconductor polyiner:PC61BM. When introducing the alternative acceptor N,N'-bis(1-ethylpropyl)-3,4:9,10-perylenediimide (PDI), high ON/OFF ratios are achieved for 95:5 wt % semiconductor polymer:PDI; however, electron conduction increases for 50:50 and 5:95 wt % semiconductor polymer:PDI. As described within, we show that electron conduction is practically eliminated when additive domains do not percolate across the OFET channel, that is, electrons are "morphologically trapped". Morphologies were characterized by optical, electron, and atomic force microscopy as well as X-ray scattering techniques. PC61BM was substituted with an endohedral Lu3N fullerene, which enhanced contrast in electron microscopy and allowed for more detailed insight into the blend morphologies. Blends with alternative, nonfullerene acceptors further emphasize the importance of morphology and acceptor percolation, providing insights for such blends that control ambipolar transport and ON/OFF ratios.

• 出版日期2018-7
• 单位苏州大学