Solution-Processable BODIPY-Based Small Molecules for Semiconducting Microfibers in Organic Thin-Film Transistors

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• 作者：Mehmet Ozdemir ; Donghee Choi ; Guhyun Kwon ; Yunus Zorlu ; Bunyemin Cosut ; Hyekyoung Kim ; Antonio Facchetti ; Choongik Kim ; Hakan Usta
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：8
• 期：22
• 页码：14077-14087
• 全文大小：607K
• 年卷期：0
• ISSN：1944-8252

文摘

Electron-deficient π-conjugated small molecules can function as electron-transporting semiconductors in various optoelectronic applications. Despite their unique structural, optical, and electronic properties, the development of BODIPY-based organic semiconductors has lagged behind that of other π-deficient units. Here, we report the design and synthesis of two novel solution-proccessable BODIPY-based small molecules (BDY-3T-BDY and BDY-4T-BDY) for organic thin-film transistors (OTFTs). The new semiconductors were fully characterized by ¹H/¹³C NMR, mass spectrometry, cyclic voltammetry, UV–vis spectroscopy, photoluminescence, differential scanning calorimetry, and thermogravimetric analysis. The single-crystal X-ray diffraction (XRD) characterization of a key intermediate reveals crucial structural properties. Solution-sheared top-contact/bottom-gate OTFTs exhibited electron mobilities up to 0.01 cm²/V·s and current on/off ratios of >10⁸. Film microstructural and morphological characterizations indicate the formation of relatively long (∼0.1 mm) and micrometer-sized (1–2 μm) crystalline fibers for BDY-4T-BDY-based films along the shearing direction. Fiber-alignment-induced charge-transport anisotropy (μ_∥/μ_⊥ ≈ 10) was observed, and higher mobilities were achieved when the microfibers were aligned along the conduction channel, which allows for efficient long-range charge-transport between source and drain electrodes. These OTFT performances are the highest reported to date for a BODIPY-based molecular semiconductor, and demonstrate that BODIPY is a promising building block for enabling solution-processed, electron-transporting semiconductor films.