Dresden 2020 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 17: Organic Thin Films, Organic-Inorganic Interfaces II (joint session DS/CPP)

DS 17.4: Vortrag

Dienstag, 17. März 2020, 12:00–12:15, CHE 91

Growth of Extended DNTT Fibers on Metal Substrates by Suppression of Step-Induced Nucleation — •Maximilian Dreher, Dayeon Kang, Tobias Breuer, and Gregor Witte — Philipps-Universität Marburg, 35032 Marburg, Germany

Due to their anisotropic optoelectronic properties, crystalline organic fibers constitute an interesting class of nanoscale materials with great potential for integration into future optoelectronic devices based on organic-inorganic hybrid systems. While chemical synthesis allows for flexible tailoring of electronic molecular properties, structural control of hybrid structures is hampered by the incompatibility of traditional structuring methods. Here we examine the formation of crystalline fibers of dinaphthothienothiophene (DNTT), a recently synthesized organic semiconductor with high charge carrier mobility, upon film growth on noble metal substrates. Based on a comparison of the film growth on a regularly stepped, vicinal surface, we show by STM measurements that substrate steps affect the azimuthal molecular orientation in the seed layer. In particular, they induce a fiber orientation which competes with that of fibers formed on flat terraces and thereby strongly limits the fiber dimensions. We demonstrate a strategy to suppress this parasitical step-induced fiber nucleation by first exposing Ag(111) surfaces to oxygen, which causes a selective saturation of the active step sites, while subsequent deposition of DNTT yields strongly enlarged fibers that are epitaxially aligned on the (111) surface [1,2]. [1] M. Dreher et al., Adv. Mater. Interfaces 5, 1800920 (2018) [2] M. Dreher et al., Nanoscale Horiz. 4, 1353-1360 (2019)