Large-area single-crystal organic patterned thin films by vertically confined lateral crystal growth via capillary force lithography

• Published in: Applied surface science 2019-11, Vol.494, p.1023-1029
• Main Authors: Park, Yoonkyung, Park, Jinseon, Cho, Sangho, Sung, Myung Mo
• Format: Article
• Language: English
• Subjects: Capillary force lithography; High mobility; Large-area fabrication; Organic field-effect transistor; Single crystal organic thin film; Vertical confinement
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.07.184

We report a one-step fabrication method for large-area single-crystal organic thin films guided through vertically confined lateral crystal growth via capillary force lithography (VC-LCG via CLF). In this method, organic molecules in ink solutions self-assemble and crystallize within the vertically confined channels of patterned molds. Vertical confinement, determined by the channel depth, played a major role with regard to the crystallization and formation of single-crystalline organic thin films. We also demonstrated its usefulness by fabricating wafer-scale arrays of single-crystal organic thin film transistors with high performance and uniformly distributed electrical properties, which could be attributed to their large-scale single-crystalline nature, homogeneous film morphologies and the suppression of multiple crystal orientations. Especially, the versatility to various organic molecules, ease of processing optimization, and uniform crystallinity all over the patterned area increase the possibility of VC-LCG to apply in the industrial process. [Display omitted] •One-step fabrication method for large-area single-crystal organic thin films guided through VC-LCG via CLF was developed.•Self-assembly of organic molecules within shallow channel depth is crucial for the formation of single-crystalline organic films.•The crystalline nature of resulting homogenous films was carefully characterized by 2D XRD, out-of-plane XRD, and SEAD.•The versatility of the technique was demonstrated by using three different ink solution of TIPS-PEN, C8-BTBT, and P3HT.•Wafer-scale arrays of single-crystal OTFTs exhibited high performance and uniform electrical properties over large area.