Process optimization for inkjet printing of triisopropylsilylethynyl pentacene with single-solvent solutions

• Published in: Thin solid films Vol. 578; pp. 11 - 19
• Main Authors: Wang, Xianghua, Yuan, Miao, Xiong, Xianfeng, Chen, Mengjie, Qin, Mengzhi, Qiu, Longzhen, Lu, Hongbo, Zhang, Guobing, Lv, Guoqiang, Choi, Anthony H.W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 02.03.2015
• Subjects: Coffee-ring effect; Dispersion force; Dispersions; Inkjet printing; Organic semiconductors; Organic thin-film transistor; Pentacene; Self-assembly; Semiconductors; Solvents; Surface energy; Thin film transistors; Inkjet printing; Coffee-ring effect; Self-assembly; Dispersion force; Surface energy; Organic thin-film transistor
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2015.02.004

Inkjet printing of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN), a small molecule organic semiconductor, is performed on two types of substrates. Hydrophilic SiO2 substrates prepared by a combination of surface treatments lead to either a smaller size or a coffee-ring profile of the single-drop film. A hydrophobic surface with dominant dispersive component of surface energy such as that of a spin-coated poly(4-vinylphenol) film favors profile formation with uniform thickness of the printed semiconductor owing to the strong dispersion force between the semiconductor molecules and the hydrophobic surface of the substrate. With a hydrophobic dielectric as the substrate and via a properly selected solvent, high quality TIPS-PEN films were printed at a very low substrate temperature of 35°C. Saturated field-effect mobility measured with top-contact thin-film transistor structure shows a narrow distribution and a maximum of 0.78cm2V−1s−1, which confirmed the film growth on the hydrophobic substrate with increased crystal coverage and continuity under the optimized process condition. •Hydrophobic substrates were employed to inhibit the coffee-ring effect.•Contact-line pinning is primarily controlled by the dispersion force.•Solvent selection is critical to crystal coverage of the printed film.•High performance and uniformity are achieved by process optimization.