Unconventional nanostructures based on block copolymer self-assembly and their optical and catalytic applications

Abstract

Block copolymer self-assembly produces periodic nanostructures on a large substrate with low cost, which is a promising candidate of the next generation lithographic tool. Although many researches about block copolymer lithography and its application have been studied, there are several issues to be addressed. Firstly, the nanostructures assembled from block copolymer self-assembly are simple dot or line patterns composed of hexagonal cylinder or sphere, or linear lamellae. Secondly, pattern transfer processes using the self-assembled polymer template induces chemically homogenous metal or metal oxide nanopatterns. Those simple nanopatterns with chemical homogeneity become an obstacle for the advanced utilizations such as electronics, photonics, catalysis, and so on. In this dissertation, complex nanostructures including core-shell nanoparticles with two different core-shell elements, and 3D multimetal complex nanomeshes, and nanodot array with square symmetry were successfully fabricated by block copolymer self-assembly and other assisted techniques. Core-shell nanopatterns show synergetic effects in optical and catalytic applications including surface-enhanced Raman scattering and solid oxide fuel cell. In addition, 3D multimetallic nanomeshes were easily synthesized using perforated lamellar block copolymer self-assembly and such 3D complex nanostructures with nanoscale holes are potentially useful in catalytic application like hydrogen evolution reaction. Lastly, we generated nanodots with square array which is hard to make by conventional block copolymer self-assembly. Orthogonal stacking of lamellar nanomorphology in a topological trench induced square nanopattern and subsequent metal pattern transfer enabled the metal nanodot array with square symmetry which is a significantly important pattern in integrated circuit industry.