Use of an Underlayer for Large Area Crystallization of Rubrene Thin Films

Michael A. Fusella, Siyu Yang, Kevin Abbasi, Hyun Ho Choi, Zhuozhi Yao, Vitaly Podzorov, Amir Avishai, Barry P. Rand

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

In this work, we discovered a very efficient method of crystallization of thermally evaporated rubrene, resulting in ultrathin, large-area, fully connected, and highly crystalline thin films of this organic semiconductor with a grain size of up to 500 μm and charge carrier mobility of up to 3.5 cm2 V-1 s-1. We found that it is critical to use a 5 nm-thick organic underlayer on which a thin film of amorphous rubrene is evaporated and then annealed to dramatically influence the ability of rubrene to crystallize. The underlayer property that controls this influence is the glass transition temperature. By experimenting with different underlayers with glass transition temperatures varying over 120 °C, we identified the molecules leading to the best crystallinity of rubrene films and explained why values both above and below the optimum result in poor crystallinity. We discuss the formation of different crystalline morphologies of rubrene produced by this method and show that field-effect transistors made with films of a single-domain platelet morphology, achieved through the aid of the optimal underlayer, outperform their spherulite counterparts with a nearly four times higher charge carrier mobility. This large-area crystallization technique overcomes the fabrication bottleneck of high-mobility rubrene thin film transistors and other related devices and, given its scalability and patternability, may lead to practical technologies compatible with large-area flexible electronics.

Original languageEnglish (US)
Pages (from-to)6666-6673
Number of pages8
JournalChemistry of Materials
Volume29
Issue number16
DOIs
StatePublished - Aug 22 2017

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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    Fusella, M. A., Yang, S., Abbasi, K., Choi, H. H., Yao, Z., Podzorov, V., Avishai, A., & Rand, B. P. (2017). Use of an Underlayer for Large Area Crystallization of Rubrene Thin Films. Chemistry of Materials, 29(16), 6666-6673. https://doi.org/10.1021/acs.chemmater.7b01143