Hierarchical Orientation of Crystallinity by Block-Copolymer Patterning and Alignment in an Electric Field

Titelangaben

Goldberg-Oppenheimer, Pola ; Kabra, Dinesh ; Vignolini, Silvia ; Hüttner, Sven ; Sommer, Michael ; Neumann, Katharina ; Thelakkat, Mukundan ; Steiner, Ullrich:
Hierarchical Orientation of Crystallinity by Block-Copolymer Patterning and Alignment in an Electric Field.
In: Chemistry of Materials. Bd. 25 (2013) Heft 7 . - S. 1063-1070.
ISSN 1520-5002
DOI: https://doi.org/10.1021/cm3038075

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Abstract

Electron and hole conducting 10-nm-wide polymer morphologies hold great promise for organic electro-optical devices such as solar cells and light emitting diodes. The self-assembly of block-copolymers (BCPs) is often viewed as an efficient way to generate such materials. Here, a functional block copolymer that contains perylene bismide (PBI) side chains which can crystallize via pi-pi stacking to form an electron conducting microphase is patterned harnessing hierarchical electrohydrodynamic lithography (HEHL). HEHL film destabilization creates a hierarchical structure with three distinct length scales: (1) micrometer-sized polymer pillars, containing (2) a 10-nm BCP microphase morphology that is aligned perpendicular to the substrate surface and (3) on a molecular length scale (0.35-3 nm) PBI pi-pi-stacks traverse the HEHL-generated plugs in a continuous fashion. The good control over BCP and PBI alignment inside the generated vertical microstructures gives rise to liquid-crystal-like optical dichroism of the HEHL patterned films, and improves the electron conductivity across the film by 3 orders of magnitude.