Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 16: Organic Semiconductors
HL 16.4: Vortrag
Dienstag, 18. März 2025, 10:15–10:30, H14
Detecting charge patterns on a novel type of rubrene crystals by time-of-flight photoemission electron microscopy — •Moha Naeimi1,2, Ingo Barke1,2, and Sylvia Speller1,2 — 1University of Rostock, Institute of physics, Rostock, Germany — 2University of Rostock, Department of life, light and matter, Rostock, Germany
Organic molecules are increasingly drawing attention due to their broad applications, not only in organic field effect transistors and organic light emitting diodes [1], but also with respect to the exciton dynamics and charge transfer [2]. To this end, single crystalline domains with compact and stable molecular packing are beneficial. In this work, we focus on charge patterns and its dynamics for a recently discovered type of rubrene single crystals consisting of two distinct types of domains [3]. We show that both domains exhibit different charging properties, and that one of them can be controlled by photon exposure. This charge pattern can be *reset* by a second light source with lower photon energy, essentially neutralizing the charged sections. We tentatively attribute the behavior to the selective photo-injection of mobile excitons, resulting in spatially dependent conductivities.
[1] Wei-Cheng Su et al., Influence of Singlet and Charge-Transfer Excitons on the Open-Circuit Voltage of Rubrene/Fullerene Organic Photovoltaic Device ACS Appl. Mater. Interfaces, 8, 28757-28762 (2016) [2] Drew M. Finton et al., Routes to singlet exciton fission in rubrene crystals and amorphous films AIP Advances 9, 095027 (2019) [3] Moha Naeimi et al., Characteristics of zone-sectored tabular orthorhombic rubrene microcrystals in preparation.
Keywords: rubrene; photoemission; exciton