Solvent-Free Coating of Organic Semiconductor Membranes with Centimetric Crystalline Domains

Yu Xia, Ruipeng Li, Esther Tsai, Yaowu He, Tianran Liu, Xiaoming Zhao, Kaichen Gu, Hong Meng, Yueh Lin Loo

Research output: Contribution to journalArticlepeer-review

Abstract

Organic semiconductors (OSCs) have shown great promise in a variety of applications. Although solution processing of OSCs has resulted in high-quality films, exquisite control of structural development to minimize defect formation during large-scale fabrication remains formidable. Compounding this challenge is the use of halogenated organic solvents, which poses significant health and environmental hazards. However, the solvent-free techniques introduced thus far impose additional limitations on solidification kinetics; the resulting OSC thin films are often more defective than those processed from solution. Here, a solvent-free technique is reported to prepare OSC membranes with centimetric crystalline domains. Leveraging the tendency for liquid crystalline materials to preferentially orient, OSCs are “prealigned” by depositing them from the melt over a metal frame to form a freely suspended membrane. Crystallization from this prealigned phase affords membranes with unprecedented structural order across macroscopic distances. Field-effect transistors comprising membranes of dioctyl[1]-benzothieno[3,2-b][1]benzothiophene (C8BTBT) and didodecyl[1]-benzothieno[3,2-b][1]benzothiophene (C12BTBT) having centimeter-sized domains as active layers exhibit a hole mobility of ≈8.6 cm2 V−1 s−1, superseding the mobility of any transistors whose active layers are deposited from melt. This technique is scalable to yield membranes with large crystalline domains over wafer dimensions, making it amenable for broad applications in large-area organic electronics.

Original languageEnglish (US)
Article number2000792
JournalAdvanced Electronic Materials
Volume7
Issue number3
DOIs
StatePublished - Mar 2021

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

Keywords

  • melt processing
  • organic semiconductors
  • single crystals
  • smectic liquid crystals
  • solvent-free coatings

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