Gating upconversion electroluminescence in a single molecule via adsorption-induced interaction of unpaired spin

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Hauptverfasser: Rai, Vibhuti N., Holzer, Christof, Rockstuhl, Carsten, Wulfhekel, Wulf, Gerhard, Lukas
Format: Preprint
Veröffentlicht: 2025
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author Rai, Vibhuti N.
Holzer, Christof
Rockstuhl, Carsten
Wulfhekel, Wulf
Gerhard, Lukas
author_facet Rai, Vibhuti N.
Holzer, Christof
Rockstuhl, Carsten
Wulfhekel, Wulf
Gerhard, Lukas
contents Molecules with unpaired spins (radicals) offer promising alternatives to closed-shell molecules as they are less limited regarding the spin statistics in their electroluminescence. Here, we combine scanning tunneling microscopy induced luminescence and density functional theory to study single vanadyl phthalocyanine molecules, which are stable neutral radicals. Two distinct adsorption geometries of the molecule on NaCl/Au(111) lead to a difference in the interaction of the unpaired electron with the substrate, which in turn allows us to investigate its effects on the light emission process. Remarkably, we observe that up-conversion electroluminescence is gated by the adsorption geometry of the molecule, an effect we attribute to a reordering of excited states and enhanced excited state transition probabilities. The profound influence of the unpaired electron via state reordering opens new possibilities for tuning not only molecular electroluminescence but also many other spin dependent phenomena.
format Preprint
id arxiv_https___arxiv_org_abs_2508_11501
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gating upconversion electroluminescence in a single molecule via adsorption-induced interaction of unpaired spin
Rai, Vibhuti N.
Holzer, Christof
Rockstuhl, Carsten
Wulfhekel, Wulf
Gerhard, Lukas
Mesoscale and Nanoscale Physics
Molecules with unpaired spins (radicals) offer promising alternatives to closed-shell molecules as they are less limited regarding the spin statistics in their electroluminescence. Here, we combine scanning tunneling microscopy induced luminescence and density functional theory to study single vanadyl phthalocyanine molecules, which are stable neutral radicals. Two distinct adsorption geometries of the molecule on NaCl/Au(111) lead to a difference in the interaction of the unpaired electron with the substrate, which in turn allows us to investigate its effects on the light emission process. Remarkably, we observe that up-conversion electroluminescence is gated by the adsorption geometry of the molecule, an effect we attribute to a reordering of excited states and enhanced excited state transition probabilities. The profound influence of the unpaired electron via state reordering opens new possibilities for tuning not only molecular electroluminescence but also many other spin dependent phenomena.
title Gating upconversion electroluminescence in a single molecule via adsorption-induced interaction of unpaired spin
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2508.11501