Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 26: Poster II

HL 26.15: Poster

Mittwoch, 11. März 2026, 09:30–11:30, P1

Low temperature photoluminescence excitation spectroscopy on thin film zinc phthalocyanine — •Josephine Braun, Sebastian Hammer, and Jens Pflaum — Experimental Physics 6, University of Würzburg, 97074 Würzburg, Germany

The optical properties of molecular semiconductors are determined by the electronic properties of the molecular constituents and their respective inter-molecular (IM) interaction [1]. To disclose the IM interaction, polymorphic materials like Zinc-phthalocyanine (ZnPc) provide perfect prototypical systems [2]. Its luminescence in the α-phase is dominated by excimer emission [3], wheras the β-phase luminescence is governed by a highly temperature sensitive Frenkel exciton emission. While temperature dependent luminescence studies provide insight into the IM interaction potential, the excitation spectrum does the same without being prone to effects of excitonic relaxation. In this contribution we investigate the excitonic system of ZnPc thin films in the α- and β-phase via temperature dependent photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopy between 4 K and 300 K. We show, that while the PL spectra exhibits strong variability with temperature, the PLE spectra show only minor changes. This suggests that rather than a large modulation of the IM interaction with temperature, exitonic relaxation processes are at the heart of ZnPc’s pronounced spectral luminescence changes.

[1] Hestand and Spano, Chem. Rev. 118 (2018), p. 7069–7163
[2] Hammer et al., Appl. Phys. Lett. 115 (2019), p. 263303
[3] Hammer et al., Mater. Horiz. 10 (2023), p. 221–234

Keywords: zinc phthalocyanine; photoluminescence; photoluminescence ecxitation spectroscopy; Frenkel exciton; molecular crystals