Enhancing Molecular Alignment and Charge Transport of Solution‐Sheared Semiconducting Polymer Films by the Electrical‐Blade Effect. (21st May 2018)

• Record Type: Journal Article
• Authors: Molina‐Lopez, Francisco; Wu, Hung‐Chin; Wang, Ging‐Ji Nathan; Yan, Hongping; Shaw, Leo; Xu, Jie; Toney, Michael F.; Bao, Zhenan
• Is Part Of: Advanced Electronic Materials. Volume 4:Number 7(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-21
• Subjects: conjugated polymers -- organic field effect transistors -- organic semiconductors -- polymer chain alignment -- solution‐shearing; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.201800110
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: Controlling polymer chain alignment through processing is a means of tuning the charge transport of solution‐based conjugated polymers. In this work, a processing strategy is proposed in which an external electric field (E‐field) is applied to the coating blade (E‐blade) to align polymer chain during solution‐shearing, a meniscus‐guided coating technique. A theoretical model based on dielectrophoresis quantitatively describes and predicts the alignment process and is used to guide the selection of the optimal conditions of the applied E‐field. Using these conditions, more than twofold increase in chain alignment is observed for E‐bladed thin films of a diketopyrrolopyrrole (DPP) semiconducting polymer without affecting other morphological aspects such as film thickness, film coverage, or fiber‐like aggregation. Organic field effect transistors based on the E‐bladed DPP polymer are fabricated at ambient conditions and over areas of a few cm 2 . They display a threefold improvement in their mobilities and a strong enhancement in charge transport anisotropy compared to films prepared without E‐field. These results reveal a synergistic alignment effect from both the solution‐shearing process and the applied E‐field, and introduce a novel and general approach to control the morphology and the electrical properties of solution‐coated conjugated polymer thin films. Abstract : Solution‐processing of organic functional materials can potentially enable large‐area and low‐cost fabrication of electronics . Tuning the morphology of solution‐processed semiconducting polymers is key for achieving high performance. Here, the use of an electric field, via dielectrophoresis, to control molecular alignment in solution‐coated semiconducting polymer films, thus increasing their field effect transistor mobility in a threefold, is demonstrated.