Directed Self-Assembly of the Organic Semiconductor C8-BTBT-C8 in Anodic Aluminum Oxide Nanopores

Journal Article · Wed Dec 24 00:00:00 EST 2025 · ACS Applied Nano Materials

DOI:https://doi.org/10.1021/acsanm.5c04558· OSTI ID:3011685

Li, Zhuoqing ^[1]; Sentker, Kathrin ^[2]; Brinker, Manuel ^[2]; Lippmann, Milena Dimitrova ^[3]; Seeck, Oliver H. ^[3]; Kityk, Andriy V. ^[4]; Ocko, Benjamin M. ^[5]; Huber, Patrick ^[1]

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1. Hamburg University of Technology (Germany); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2. Hamburg University of Technology (Germany)
3. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
4. Czestochowa University of Technology (Poland)
5. Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)

Controlling the self-assembly of organic semiconductors at the nanoscale is critical for advancing high-performance electronic and photonic devices, yet it remains challenging due to their intrinsic anisotropic crystallization and sensitivity to processing conditions. Here, in this study, we demonstrate that cylindrical nanoconfinement within anodic aluminum oxide membranes provides a versatile platform to precisely tune the molecular orientation and phase behavior of the prototypical organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). Combining temperature-dependent high-resolution synchrotron X-ray scattering with optical birefringence measurements, we uncover that confinement geometries (pore diameters 25–180 nm) and surface chemistry govern the emergence of distinct smectic A textures, featuring molecular layers either parallel or perpendicular to the pore axis. The competition between axial and radial smectic layering is modulated by pore size, surface hydrophilicity, and thermal history, enabling reversible control over domain orientations and transitions between liquid crystalline and crystalline states. Notably, nanoconfinement stabilizes the smectic phase over an expanded temperature range compared to bulk, while inducing complex multidomain configurations owing to geometric constraints and anchoring conditions. Our results elucidate fundamental mechanisms by which anisotropic nanoscale confinement directs the self-organization of highly conjugated organic molecules, with implications for optimizing directional charge transport and anisotropic optical responses in organic–inorganic hybrid nanoarchitectures. This study establishes nanoconfinement as a powerful strategy to engineer morphology and functional properties in organic semiconducting materials with nanoscale precision.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: SC0012704
• OSTI ID: 3011685
• Report Number(s): BNL--229287-2025-JAAM
• Journal Information: ACS Applied Nano Materials, Journal Name: ACS Applied Nano Materials Journal Issue: 1 Vol. 9; ISSN 2574-0970
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
X-ray scattering
nanoconfinement
nanoporous material
optical birefringence
self-assembly
smectic liquid crystal