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arXiv · 2603.02911

Dual-wavelength control of charge accumulation in rubrene microcrystals with anisotropic conductivity

Moha Naeimi·Ingo Barke·Sylvia Speller
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Abstract

Previously, a novel type of rubrene microcrystals was reported, forming two distinct sectors -- diamond- and triangular-shaped -- that exhibit pronounced contrasts in photoluminescence (PL) spectra and exciton dynamics. In the present work, their internal electronic structure is investigated using time-of-flight photoemission electron spectroscopy (TOF-PES), revealing that the two sector's different charging characteristics arising from anisotropic conductivities. Upon photoemission via a one-photon photoemission (1PPE) process excited by 6.2 eV (200 nm) photons, the diamond-shaped sectors accumulate significant charge, whereas the triangular sectors remain essentially uncharged. The charge accumulation in the diamond sectors can be neutralized by additional sub-threshold illumination, which generates charge carriers through internal photoeffect. The dynamics and energetics of the observed band shifting is described quantitatively by a model combining surface capacitance and drift-diffusion. These crystalline systems enable the creation of built-in charge landscapes that can be manipulated both spatially and temporally.

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Moha Naeimi, Ingo Barke, Sylvia Speller. 2026-03-03. Dual-wavelength control of charge accumulation in rubrene microcrystals with anisotropic conductivity. https://arxiv.org/abs/2603.02911

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