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DS: Fachverband Dünne Schichten

DS 18: Optical Analysis of Organic Thin Films

DS 18.3: Talk

Thursday, March 21, 2024, 17:30–17:45, A 060

Correlating Optical Transitions and the Selective Enhancement of Vibrational Modes in the Different Crystalline Phases of Semiconducting Discrete Oligomers — •Alexander Ehm, Rukiya Matsidik, Lukas Hertling, Michael Sommer, and Dietrich R. T. Zahn — TU Chemnitz, Chemnitz D-09107, Germany

The ever-growing zoo of organic semiconductors has a great potential to provide material-efficient, low-cost, and highly versatile alternatives, or supplementation, for (opto-)electronic applications. Recently developed naphthalene diimide- (NDI) and bithiophene- (T2) based, discrete oligomers avoid the typical disadvantages of polymeric semiconductors, such as batch-to-batch variation and high dispersity, while exhibiting opto-electronic properties similar to their polymeric counterparts [1]. Excitation-dependent Raman spectroscopy of the well-studied polymer P(NDI2OD-T2) comprising the same molecular units as the discrete oligomers, indicated selective enhancement of certain Raman modes linked to polaron confinement [2].

In our studies, we investigate the selective enhancement of Raman modes using a multitude of excitations of the discrete NDI-T2-based oligomers in dependence on their annealing-induced crystallisation. The results are supported by density functional theory calculations and correlated with optical transitions as obtained from transmission spectroscopy and spectroscopic ellipsometry investigations.

[1] Matsidik et al. J. Am. Chem. Soc. 2023, 145, 8430

[2] Giussani et al. Macromolecules 2013, 46, 2658

Keywords: organic semiconductor; Raman; Ellipsometry; donor-acceptor molecule