Contact-Induced Nucleation in High-Performance Bottom-Contact Organic Thin Film Transistors Manufactured by Large-Area Compatible Solution Processing

Muhammad Rizwan Niazi, Ruipeng Li, Maged Abdelsamie, Kui Zhao, Dalaver H. Anjum, Marcia M. Payne, John Anthony, Detlef-M. Smilgies, Aram Amassian

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Scalable manufacturing of small-molecule organic thin film transistors (OTFTs) with performance approaching single crystals requires extraordinary control over microstructures and morphologies of organic semiconductors (OSCs). Here, contact-induced nucleation in the context of small-molecule OSCs and OSC:polymer blends prepared by blade coating, a printing process capable of mimicking large area batch and roll-to-roll manufacturing, is investigated. Using polarized optical microscopy, microbeam grazing incidence wide angle X-ray scattering, and energy-filtered transmission electron microscopy, it is revealed that previous design rules drawn from spin coating of OSCs and contact-induced nucleation may have to be revisited in the context of blade coating. It is shown that blade coating achieves texture purity in case of 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES-ADT), irrespective of whether the contact is chemically treated with a halogenated self-assembled monolayer (SAM) or not, in contrast to spin coating which requires an SAM. Here, it is demonstrated that OSC-contact interactions increase the nucleation density and can disrupt the vertical stratification in polymer:OSC blends with great detrimental effects on carrier transport. Using these lessons, we demonstrate bottom-contact bottom-gate OTFTs without chemical surface modification achieving hole mobilities of 4.6 and 3.6 cm2 V-1 s-1, using 6,13-bis(triisopropylsilylethynyl)pentacene and diF-TES-ADT, respectively, blended with an insulating polymer. Contact-induced nucleation, normally a desirable effect when spin-coating organic semiconductors (OSC), is shown to disrupt the crystallization of large OSC domains and to alter the vertical stratification of otherwise high-performance polymer:OSC blends.
Original languageEnglish (US)
Pages (from-to)2371-2378
Number of pages8
JournalAdvanced Functional Materials
Volume26
Issue number14
DOIs
StatePublished - Sep 30 2015

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