Tailored nanomesh structures via pore engineering, based on block copolymer self-assembly and their applications

Abstract

For maximizing device performance, tailoring the material structure according to desired property, such as optical and electrical properties, is essential. 5~100 nm highly periodic nanopattern can be introduced over a large area with uniform distribution using block copolymer self-assembly. With proper pattern transfer process, various types of materials can be easily patterned with high ordering. However, due to the intrinsic phase separation behavior of block copolymer self-assembly, only relatively simple pattern is introduced. Accordingly, block copolymer self-assembly based materials are hard to integrate with various devices and applications. In this regard, precise control of macropore and mesopore of self-assembled pattern is inevitable for applying various applications. In this dissertation, unconventional nanomesh structures via pore engineering were successfully introduced. Especially, as introducing macropore using colloidal self-assembly and polymer film dewetting, hierarchical nanomesh can be generated. Hierarchical nanomesh have abundant pore and surface area, so that high performance and transparent gas sensor devices was demonstrated. Moreover, due to its transparent character, hierarchical mesh-based gas sensor can be easily integrated with other functional devices. Also, we can successfully demonstrate mesopore of block copolymer nanomesh using initiated chemical vapor deposition for introducing pore size controlled isoporous membrane. This size tuned membrane can sieve the solute size with nanometer size variation. Furthermore, surface charged membrane can filter the smaller solute than its pore size. Finally, MXene nanomesh was introduced using judicious sequential etching process. We verified physical and chemical structure of nanopatterned MXene and applied it to thermoelectric device for unveiling its electrical and thermal conduction mechanism.