The ability to control the emission from single-molecule quantum emitters is an important step toward their implementation in optoelectronic technology. Phthalocyanine and derived metal complexes on thin insulating layers studied by scanning tunneling microscope-induced luminescence (STML) offer an excellent playground for tuning their excitonic and electronic states by Coulomb interaction and to showcase their high environmental sensitivity. Copper phthalocyanine (CuPc) has an open-shell electronic structure, and its lowest-energy exciton is a doublet, which brings interesting prospects in its application for optospintronic devices. Here, we demonstrate that the excitonic state of a single CuPc molecule can be reproducibly switched by atomic-scale manipulations permitting precise positioning of the molecule on the NaCl ionic crystal lattice. Using a combination of STML, AFM, and ab initio calculations, we show the modulation of electronic and optical bandgaps and the exciton binding energy in CuPc by tens of meV. We explain this effect by spatially dependent Coulomb interaction occurring at the molecule-insulator interface, which tunes the local dielectric environment of the emitter.

Department of Petrochemistry and Refining University of Kinshasa Kinshasa Democratic Republic of Congo

Faculty of Mathematics and Physics Charles University Ke Karlovu 3 CZ12116 Praha 2 Czech Republic

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo náměstí 542 2 CZ16000 Praha Czech Republic

Institute of Physics Czech Academy of Sciences Cukrovarnická 10 112 CZ16200 Praha 6 Czech Republic

Instituto de Ciencia de Materiales de Madrid CSIC Sor Juana Inés de la Cruz 3 E28049 Madrid Spain

Instituto de Física Fundamental CSIC Serrano 121 E28006 Madrid Spain

Regional Centre of Advanced Technologies and Materials Šlechtitelů 27 CZ78371 Olomouc Czech Republic

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Moerner WE. Examining Nanoenvironments in Solids on the Scale of a Single, Isolated Impurity Molecule. Science. 1994;265:46–53. PubMed

Moerner WE. Nobel Lecture: Single-molecule spectroscopy, imaging, and photocontrol: Foundations for super-resolution microscopy. Rev Mod Phys. 2015;87:1183–1212. PubMed

Zhu XY, Yang Q, Muntwiler M. Charge-Transfer Excitons at Organic Semiconductor Surfaces and Interfaces. Acc Chem Res. 2009;42(11):1779–1787. PubMed

Raja A, et al. Coulomb engineering of the bandgap and excitons in two-dimensional materials. Nat Commun. 2017;8 15251. PubMed PMC

Ugeda MM, et al. Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor. Nat Mater. 2014;13:1091–5. PubMed

Walsh AG, et al. Screening of Excitons in Single, Suspended Carbon Nanotubes. Nano Lett. 2007;7:1485–1488. PubMed

Deslippe J, et al. Electron-Hole Interaction in Carbon Nanotubes: Novel Screening and Exciton Excitation Spectra. Nano Lett. 2009;9:1330–1334. PubMed

Kuhnke K, Große C, Merino P, Kern K. Atomic-Scale Imaging and Spectroscopy of Electroluminescence at Molecular Interfaces. Chem Rev. 2017;117(7):5174–5222. PubMed

Merino P, Große C, Rosławska A, Kuhnke K, Kern K. Exciton dynamics of C60-based single-photon emitters explored by Hanbury Brown-Twiss scanning tunnelling microscopy. Nat Commun. 2015;6 8461. PubMed PMC

Zhang Y, et al. Visualizing coherent intermolecular dipole-dipole coupling in real space. Nature. 2016;531:623–627. PubMed

Luo Y, et al. Electrically Driven Single-Photon Superradiance from Molecular Chains in a Plasmonic Nanocavity. Phys Rev Lett. 2019;122 233901. PubMed

Doppagne B, et al. Electrofluorochromism at the single-molecule level. Science. 2018;361:251–255. PubMed

Imada H, et al. Real-space investigation of energy transfer in heterogeneous molecular dimers. Nature. 2016;538:364–367. PubMed

Doppagne B, et al. Single-molecule tautomerization tracking through space- and time-resolved fluorescence spectroscopy. Nat Nanotechnol. 2020;15:207–211. PubMed

Große C, et al. Submolecular Electroluminescence Mapping of Organic Semiconductors. ACS Nano. 2017;11(2):1230–1237. PubMed

Große C, Gunnarsson O, Merino P, Kuhnke K, Kern K. Nanoscale Imaging of Charge Carrier and Exciton Trapping at Structural Defects in Organic Semiconductors. Nano Lett. 2016;16:2084–2089. PubMed

Goushi K, Yoshida K, Sato K, Adachi C. Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion. Nat Photonics. 2012;6:253–258.

Becker MA, et al. Bright triplet excitons in caesium lead halide perovskites. Nature. 2018;553:189–193. PubMed

Ai X, et al. Efficient radical-based light-emitting diodes with doublet emission. Nature. 2018;563:536–540. PubMed

Doležal J, et al. Charge carrier injection electroluminescence with CO functionalized tips on single molecular emitters. Nano Lett. 2019 PubMed PMC

Vincett PS, Voigt EM, Rieckhoff KE. Phosphorescence and Fluorescence of Phthalocyanines. J Chem Phys. 1971;55:4131–4140.

Caplins BW, Mullenbach TK, Holmes RJ, Blank DA. Femtosecond to nanosecond excited state dynamics of vapor deposited copper phthalocyanine thin films. Phys Chem Chem Phys. 2016;18:11454–11459. PubMed

Uemura T, et al. Local-plasmon-enhanced up-conversion fluorescence from copper phthalocyanine. Chem Phys Lett. 2007;448:232–236.

Repp J, Meyer G, Stojković SM, Gourdon A, Joachim C. Molecules on insulating films: scanning-tunneling microscopy imaging of individual molecular orbitals. Phys Rev Lett. 2005;94 026803. PubMed

Ellner M, et al. The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy. Nano Lett. 2016;16:1974–1980. PubMed

Scheuerer P, et al. Charge-Induced Structural Changes in a Single Molecule Investigated by Atomic Force Microscopy. Phys Rev Lett. 2019;123 66001. PubMed

Mohn F, Gross L, Moll N, Meyer G. Imaging the charge distribution within a single molecule. Nat Nanotechnol. 2012;7:227–231. PubMed

Zahn DRT, Gavrila GN, Gorgoi M. The transport gap of organic semiconductors studied using the combination of direct and inverse photoemission. Chem Phys. 2006;325:99–112.

Hill IG, Kahn A, Soos ZG, Pascal RA., J Charge-separation energy in films of π-conjugated organic molecules. Chem Phys Lett. 2000;327:181–188.

Knupfer M. Exciton binding energies in organic semiconductors. Appl Phys A. 2003;77:623–626.

Chen G, et al. Spin-Triplet-Mediated Up-Conversion and Crossover Behavior in Single-Molecule Electroluminescence. Phys Rev Lett. 2019;122 177401. PubMed

Blum V, et al. Ab initio molecular simulations with numeric atom-centered orbitals. Comput Phys Commun. 2009;180:2175–2196.

Tkatchenko A, Scheffler M. Accurate Molecular Van Der Waals Interactions from Ground-State Electron Density and Free-Atom Reference Data. Phys Rev Lett. 2009;102 73005. PubMed

van Lenthe E, Baerends EJ, Snijders JG. Relativistic regular two-component Hamiltonians. J Chem Phys. 1993;99:4597–4610.

Chai J-D, Head-Gordon M. Long-range corrected hybrid density functionals with damped atom-atom dispersion corrections. Phys Chem Chem Phys. 2008;10:6615–6620. PubMed

Vydrov OA, Scuseria GE. Assessment of a long-range corrected hybrid functional. J Chem Phys. 2006;125 234109. PubMed

Vydrov OA, Heyd J, Krukau AV, Scuseria GE. Importance of short-range versus long-range Hartree-Fock exchange for the performance of hybrid density functionals. J Chem Phys. 2006;125 74106. PubMed

Vydrov OA, Scuseria GE, Perdew JP. Tests of functionals for systems with fractional electron number. J Chem Phys. 2007;126 154109. PubMed

Schäfer A, Horn H, Ahlrichs R. Fully optimized contracted Gaussian basis sets for atoms Li to Kr. J Chem Phys. 1992;97:2571–2577.

Schäfer A, Huber C, Ahlrichs R. Fully optimized contracted Gaussian basis sets of triple zeta valence quality for atoms Li to Kr. J Chem Phys. 1994;100:5829–5835.

Becke AD. Density-functional thermochemistry III The role of exact exchange. J Chem Phys. 1993;98:5648–5652.

Lee C, Yang W, Parr RG. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys Rev B. 1988;37:785–789. PubMed

Stephens PJ, Devlin FJ, Chabalowski CF, Frisch MJ. Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields. J Phys Chem. 1994;98:11623–11627.

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