Dresden 2026 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.50: Poster

Donnerstag, 12. März 2026, 18:30–20:30, P2

Towards Study of Charge Transport Mechanisms Across Grain Boundaries in Organic Monolayer Films via Near-Field Photocurrent Spectroscopy — •Jian Xiao, Francesca Falorsi, Lukas Renn, and Thomas Weitz — Georg-August-University Göttingen, Göttingen, Germany

Organic semiconductors, particularly emerging organic thin films (OTFs) comprising one to several molecular layers, enable diverse nanoscale (opto-)electronic devices. Device performance critically depends on the crystalline order within OTFs, where grain boundaries (GBs) between dissimilarly oriented domains are widely recognized as limiting factors for charge transport. While previous studies have identified two GB types, barriers and valleys, distinguished by whether their lowest unoccupied molecular orbitals (LUMOs) lie above or below those of bulk grains, the detailed transport mechanisms across these interfaces remain poorly understood.

We will report our current efforts to develop scanning near-field optical microscopy (SNOM) to investigate excited photocurrents across GBs in organic monolayer films under illumination with photon energies comparable to the energy differences between GBs and bulk grains. Our approach aims to elucidate charge transport pathways across GBs and their contribution to macroscopic current formation. We further examine how GB type and the magnitude of interfacial energy differences influence transport mechanisms. These insights may inform charge transport studies across barriers in other optoelectronic material systems.

Keywords: Charge Transport; Organic Monlayer Film; Grain Boundary; Near-Field Photocurrent Spectroscopy; Organic Semiconductors