1
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Hung TC, Godinez-Loyola Y, Steinbrecher M, Kiraly B, Khajetoorians AA, Doltsinis NL, Strassert CA, Wegner D. Activating the Fluorescence of a Ni(II) Complex by Energy Transfer. J Am Chem Soc 2024; 146:8858-8864. [PMID: 38513215 PMCID: PMC10996004 DOI: 10.1021/jacs.3c07716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 03/23/2024]
Abstract
Luminescence of open-shell 3d metal complexes is often quenched due to ultrafast intersystem crossing (ISC) and cooling into a dark metal-centered excited state. We demonstrate successful activation of fluorescence from individual nickel phthalocyanine (NiPc) molecules in the junction of a scanning tunneling microscope (STM) by resonant energy transfer from other metal phthalocyanines at low temperature. By combining STM, scanning tunneling spectroscopy, STM-induced luminescence, and photoluminescence experiments as well as time-dependent density functional theory, we provide evidence that there is an activation barrier for the ISC, which, in most experimental conditions, is overcome. We show that this is also the case in an electroluminescent tunnel junction where individual NiPc molecules adsorbed on an ultrathin NaCl decoupling film on a Ag(111) substrate are probed. However, when an MPc (M = Zn, Pd, Pt) molecule is placed close to NiPc by means of STM atomic manipulation, resonant energy transfer can excite NiPc without overcoming the ISC activation barrier, leading to Q-band fluorescence. This work demonstrates that the thermally activated population of dark metal-centered states can be avoided by a designed local environment at low temperatures paired with directed molecular excitation into vibrationally cold electronic states. Thus, we can envisage the use of luminophores based on more abundant transition metal complexes that do not rely on Pt or Ir by restricting vibration-induced ISC.
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Affiliation(s)
- Tzu-Chao Hung
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
- Institute
for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Yokari Godinez-Loyola
- Institut
für Anorganische und Analytische Chemie, University of Münster, 48149 Münster, Germany
- Center
for Nanotechnology (CeNTech), University
of Münster, 48149 Münster, Germany
| | - Manuel Steinbrecher
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
| | - Brian Kiraly
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
| | | | - Nikos L. Doltsinis
- Institut
für Festkörpertheorie and Center for Multiscale Theory
and Computation, University of Münster, 48149 Münster, Germany
| | - Cristian A. Strassert
- Institut
für Anorganische und Analytische Chemie, University of Münster, 48149 Münster, Germany
- Center
for Nanotechnology (CeNTech), University
of Münster, 48149 Münster, Germany
- Cells in
Motion Interfaculty Centre (CiMIC) and Center for Soft Nanoscience
(SoN), University of Münster, 48149 Münster, Germany
| | - Daniel Wegner
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
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2
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Geng H, Tang J, Wu Y, Yu Y, Guest JR, Zhang R. Imaging Valley Excitons in a 2D Semiconductor with Scanning Tunneling Microscope-Induced Luminescence. ACS NANO 2024; 18:8961-8970. [PMID: 38470346 DOI: 10.1021/acsnano.3c12555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Valley excitons dominate the optoelectronic response of transition-metal dichalcogenides and are drastically affected by structural and environmental inhomogeneities localized in these materials. Critical to understanding and controlling these nanoscale excitonic changes is the ability to correlate the imaging of excitonic states with crystalline structures on the atomic scale. Here, we apply scanning tunneling microscope-induced luminescence microscopy to image valley excitons in a semiconducting transition-metal dichalcogenide monolayer decoupled by a 10 nanometer-thick hexagonal-boron-nitride flake incorporated in a lateral homojunction on an Au electrode surface. This design enables the observation of chiral excitonic emission arising from neutral and charged valley excitons of the monolayer semiconductor at ambipolar voltages with a quantum efficiency up to ∼10-5 photon/electron. The measured light helicity demonstrates considerable circular polarization dependent on the sample voltage, reaching as much as 40%. The real-space luminescence imaging maps─at subnanometer resolution─of the valley excitons reveal striking spatial variations associated with localized inhomogeneities, including surface impurities and possibly nanoscale dielectric and/or potential disorders in the monolayer. Our study introduces a promising format for 2D materials to explore and tailor their optoelectronic processes at the atomic scale.
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Affiliation(s)
- Hairui Geng
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jie Tang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yanwei Wu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yuanqin Yu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jeffrey R Guest
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Rui Zhang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
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3
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Kaiser K, Lieske LA, Repp J, Gross L. Charge-state lifetimes of single molecules on few monolayers of NaCl. Nat Commun 2023; 14:4988. [PMID: 37591847 PMCID: PMC10435478 DOI: 10.1038/s41467-023-40692-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 08/02/2023] [Indexed: 08/19/2023] Open
Abstract
In molecular tunnel junctions, where the molecule is decoupled from the electrodes by few-monolayers-thin insulating layers, resonant charge transport takes place by sequential charge transfer to and from the molecule which implies transient charging of the molecule. The corresponding charge state transitions, which involve tunneling through the insulating decoupling layers, are crucial for understanding electrically driven processes such as electroluminescence or photocurrent generation in such a geometry. Here, we use scanning tunneling microscopy to investigate the decharging of single ZnPc and H2Pc molecules through NaCl films of 3 to 5 monolayers thickness on Cu(111) and Au(111). To this end, we approach the tip to the molecule at resonant tunnel conditions up to a regime where charge transport is limited by tunneling through the NaCl film. The resulting saturation of the tunnel current is a direct measure of the lifetimes of the anionic and cationic states, i.e., the molecule's charge-state lifetime, and thus provides a means to study charge dynamics and, thereby, exciton dynamics. Comparison of anion and cation lifetimes on different substrates reveals the critical role of the level alignment with the insulator's conduction and valence band, and the metal-insulator interface state.
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Affiliation(s)
- Katharina Kaiser
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France.
| | | | - Jascha Repp
- Department of Physics, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Leo Gross
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
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4
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Doležal J, Canola S, Hapala P, de Campos Ferreira RC, Merino P, Švec M. Evidence of exciton-libron coupling in chirally adsorbed single molecules. Nat Commun 2022; 13:6008. [PMID: 36224183 PMCID: PMC9556530 DOI: 10.1038/s41467-022-33653-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/28/2022] [Indexed: 11/18/2022] Open
Abstract
Interplay between motion of nuclei and excitations has an important role in molecular photophysics of natural and artificial structures. Here we provide a detailed analysis of coupling between quantized librational modes (librons) and charged excited states (trions) on single phthalocyanine dyes adsorbed on a surface. By means of tip-induced electroluminescence performed with a scanning probe microscope, we identify libronic signatures in spectra of chirally adsorbed phthalocyanines and find that these signatures are absent from spectra of symmetrically adsorbed species. We create a model of the libronic coupling based on the Franck-Condon principle to simulate the spectral features. Experimentally measured librational spectra match very well the theoretically calculated librational eigenenergies and peak intensities (Franck-Condon factors). Moreover, the comparison reveals an unexpected depopulation channel for the zero libron of the excited state that can be effectively controlled by tuning the size of the nanocavity. Our results showcase the possibility of characterizing the dynamics of molecules by their low-energy molecular modes using µeV-resolved tip-enhanced spectroscopy. Vibronic coupling in molecules plays an essential role in photophysics. Here, the authors observe optical fingerprints of the coupling between librational states and charged excited states in a single phthalocyanine molecule chirally absorbed on a surface.
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Affiliation(s)
- Jiří Doležal
- Institute of Physics, Czech Academy of Sciences, CZ16200, Praha 6, Czech Republic. .,Faculty of Mathematics and Physics, Charles University, CZ12116, Praha 2, Czech Republic.
| | - Sofia Canola
- Institute of Physics, Czech Academy of Sciences, CZ16200, Praha 6, Czech Republic
| | - Prokop Hapala
- Institute of Physics, Czech Academy of Sciences, CZ16200, Praha 6, Czech Republic
| | | | - Pablo Merino
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, E08193, Barcelona, Spain.,Instituto de Ciencia de Materiales de Madrid; CSIC, E28049, Madrid, Spain
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, CZ16200, Praha 6, Czech Republic. .,Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, CZ16000, Praha 6, Czech Republic.
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5
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Doležal J, Canola S, Hapala P, de Campos Ferreira RC, Merino P, Švec M. Real Space Visualization of Entangled Excitonic States in Charged Molecular Assemblies. ACS NANO 2022; 16:1082-1088. [PMID: 34919384 DOI: 10.1021/acsnano.1c08816] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Entanglement of excitons holds great promise for the future of quantum computing, which would use individual molecular dyes as building blocks of their circuitry. Studying entangled excitonic eigenstates emerging in coupled molecular assemblies in the near-field with submolecular resolution has the potential to bring insight into the photophysics of these fascinating quantum phenomena. In contrast to far-field spectroscopies, near-field spectroscopic mapping permits direct identification of the individual eigenmodes, type of exciton coupling, including excited states otherwise inaccessible in the far field (dark states). Here we combine tip-enhanced spectromicroscopy with atomic force microscopy to inspect delocalized single-exciton states of charged molecular assemblies engineered from individual perylenetetracarboxylic dianhydride (PTCDA) molecules. Hyperspectral mapping of the eigenstates and comparison with calculated many-body optical transitions reveals a second low-lying excited state of the anion monomers and its role in the exciton entanglement within the assemblies. We demonstrate control over the exciton coupling by switching the assembly charge states. Our results reveal the possibility of tailoring excitonic properties of organic dye aggregates for advanced functionalities and establish the methodology to address them individually at the nanoscale.
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Affiliation(s)
- Jiří Doležal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Praha 2 CZ12116, Czech Republic
| | - Sofia Canola
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
| | - Prokop Hapala
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
| | | | - Pablo Merino
- 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
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, CZ78371 Olomouc, Czech Republic
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6
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Anantharaman SB, Jo K, Jariwala D. Exciton-Photonics: From Fundamental Science to Applications. ACS NANO 2021; 15:12628-12654. [PMID: 34310122 DOI: 10.1021/acsnano.1c02204] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Semiconductors in all dimensionalities ranging from 0D quantum dots and molecules to 3D bulk crystals support bound electron-hole pair quasiparticles termed excitons. Over the past two decades, the emergence of a variety of low-dimensional semiconductors that support excitons combined with advances in nano-optics and photonics has burgeoned an advanced area of research that focuses on engineering, imaging, and modulating the coupling between excitons and photons, resulting in the formation of hybrid quasiparticles termed exciton-polaritons. This advanced area has the potential to bring about a paradigm shift in quantum optics, as well as classical optoelectronic devices. Here, we present a review on the coupling of light in excitonic semiconductors and previous investigations of the optical properties of these hybrid quasiparticles via both far-field and near-field imaging and spectroscopy techniques. Special emphasis is given to recent advances with critical evaluation of the bottlenecks that plague various materials toward practical device implementations including quantum light sources. Our review highlights a growing need for excitonic material development together with optical engineering and imaging techniques to harness the utility of excitons and their host materials for a variety of applications.
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Affiliation(s)
- Surendra B Anantharaman
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Kiyoung Jo
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Deep Jariwala
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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7
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Cao S, Rosławska A, Doppagne B, Romeo M, Féron M, Chérioux F, Bulou H, Scheurer F, Schull G. Energy funnelling within multichromophore architectures monitored with subnanometre resolution. Nat Chem 2021; 13:766-770. [PMID: 34031563 DOI: 10.1038/s41557-021-00697-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/08/2021] [Indexed: 02/04/2023]
Abstract
The funnelling of energy within multichromophoric assemblies is at the heart of the efficient conversion of solar energy by plants. The detailed mechanisms of this process are still actively debated as they rely on complex interactions between a large number of chromophores and their environment. Here we used luminescence induced by scanning tunnelling microscopy to probe model multichromophoric structures assembled on a surface. Mimicking strategies developed by photosynthetic systems, individual molecules were used as ancillary, passive or blocking elements to promote and direct resonant energy transfer between distant donor and acceptor units. As it relies on organic chromophores as the elementary components, this approach constitutes a powerful model to address fundamental physical processes at play in natural light-harvesting complexes.
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Affiliation(s)
- Shuiyan Cao
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France.,Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Anna Rosławska
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France.
| | | | | | - Michel Féron
- Université Bourgogne Franche-Comté, FEMTO-ST, UFC, CNRS, Besançon, France
| | - Frédéric Chérioux
- Université Bourgogne Franche-Comté, FEMTO-ST, UFC, CNRS, Besançon, France
| | - Hervé Bulou
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France
| | - Fabrice Scheurer
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France
| | - Guillaume Schull
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France.
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8
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Mallada B, Błoński P, Langer R, Jelínek P, Otyepka M, de la Torre B. On-Surface Synthesis of One-Dimensional Coordination Polymers with Tailored Magnetic Anisotropy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:32393-32401. [PMID: 34227386 DOI: 10.1021/acsami.1c04693] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
One-dimensional (1D) metalloporphyrin polymers can exhibit magnetism, depending on the central metal ion and the surrounding ligand field. The possibility of tailoring the magnetic signal in such nanostructures is highly desirable for potential spintronic devices. We present low-temperature (4.2 K) scanning tunneling microscopy and spectroscopy (LT-STM/STS) in combination with high-resolution atomic force microscopy (AFM) and a density functional theory (DFT) study of a two-step synthetic protocol to grow a robust Fe-porphyrin-based 1D polymer on-surface and to tune its magnetic properties. A thermally assisted Ullmann-like coupling reaction of Fe(III)diphenyl-bromine-porphyrin (2BrFeDPP-Cl) on Au(111) in ultra-high vacuum results in long (up to 50 nm) 1D metal-organic wires with regularly distributed magnetic and (electronically) independent porphyrins units, as confirmed by STM images. Thermally controlled C-H bond activation leads to conformational changes in the porphyrin units, which results in molecular planarization steered by 2D surface confinement, as confirmed by high-resolution AFM images. Spin-flip STS images in combination with DFT self-consistent spin-orbit coupling calculations of porphyrin units with different structural conformations reveal that the magnetic anisotropy of the triplet ground state of the central Fe ion units drops down substantially upon intramolecular rearrangements. These results point out to new opportunities for realizing and studying well-defined 1D organic magnets on surfaces and demonstrate the feasibility of tailoring their magnetic properties.
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Affiliation(s)
- Benjamin Mallada
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
- Institute of Physics, The Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Piotr Błoński
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
| | - Rostislav Langer
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
- Department of Physical Chemistry, Faculty of Science, Palacký University Olomouc, 78371 Olomouc, Czech Republic
| | - Pavel Jelínek
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
- Institute of Physics, The Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
- IT4Innovations, Technical University of Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba,Czech Republic
| | - Bruno de la Torre
- Regional Centre of Advanced Technologies and Material, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, 783 71 Olomouc, Czech Republic
- Institute of Physics, The Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
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9
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Hung TC, Kiraly B, Strik JH, Khajetoorians AA, Wegner D. Plasmon-Driven Motion of an Individual Molecule. NANO LETTERS 2021; 21:5006-5012. [PMID: 34061553 PMCID: PMC8227484 DOI: 10.1021/acs.nanolett.1c00788] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/19/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate that nanocavity plasmons generated a few nanometers away from a molecule can induce molecular motion. For this, we study the well-known rapid shuttling motion of zinc phthalocyanine molecules adsorbed on ultrathin NaCl films by combining scanning tunneling microscopy (STM) and spectroscopy (STS) with STM-induced light emission. Comparing spatially resolved single-molecule luminescence spectra from molecules anchored to a step edge with isolated molecules adsorbed on the free surface, we found that the azimuthal modulation of the Lamb shift is diminished in case of the latter. This is evidence that the rapid shuttling motion is remotely induced by plasmon-molecule coupling. Plasmon-induced molecular motion may open an interesting playground to bridge the nanoscopic and mesoscopic worlds by combining molecular machines with nanoplasmonics to control directed motion of single molecules without the need for local probes.
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10
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Rosławska A, Merino P, Leon CC, Grewal A, Etzkorn M, Kuhnke K, Kern K. Gigahertz Frame Rate Imaging of Charge-Injection Dynamics in a Molecular Light Source. NANO LETTERS 2021; 21:4577-4583. [PMID: 34038142 PMCID: PMC8193635 DOI: 10.1021/acs.nanolett.1c00328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/22/2021] [Indexed: 06/12/2023]
Abstract
Light sources on the scale of single molecules can be addressed and characterized at their proper sub-nanometer scale by scanning tunneling microscopy-induced luminescence (STML). Such a source can be driven by defined short charge pulses while the luminescence is detected with sub-nanosecond resolution. We introduce an approach to concurrently image the molecular emitter, which is based on an individual defect, with its local environment along with its luminescence dynamics at a resolution of a billion frames per second. The observed dynamics can be assigned to the single electron capture occurring in the low-nanosecond regime. While the emitter's location on the surface remains fixed, the scanning of the tip modifies the energy landscape for charge injection into the defect. The principle of measurement is extendable to fundamental processes beyond charge transfer, like exciton diffusion.
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Affiliation(s)
- Anna Rosławska
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Université
de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Pablo Merino
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Instituto
de Ciencia de Materiales de Madrid, CSIC, E-28049 Madrid, Spain
- Instituto
de Física Fundamental, CSIC, E-28006 Madrid, Spain
| | | | - Abhishek Grewal
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
| | - Markus Etzkorn
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Institut
für Angewandte Physik, TU Braunschweig, D-38106 Braunschweig, Germany
| | - Klaus Kuhnke
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Institut
de Physique, École Polytechnique Fédérale de
Lausanne, CH-1015 Lausanne, Switzerland
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11
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Doležal J, Canola S, Merino P, Švec M. Exciton-Trion Conversion Dynamics in a Single Molecule. ACS NANO 2021; 15:7694-7699. [PMID: 33793192 PMCID: PMC7611190 DOI: 10.1021/acsnano.1c01318] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Charged optical excitations (trions) generated by charge carrier injection are crucial for emerging optoelectronic technologies as they can be produced and manipulated by electric fields. Trions and neutral excitons can be efficiently induced in single molecules by means of tip-enhanced spectromicroscopic techniques. However, little is known of the exciton-trion dynamics at single molecule level as this requires methods permitting simultaneous subnanometer and subnanosecond characterization. Here, we investigate exciton-trion dynamics by phase fluorometry, combining radio frequency modulated scanning tunnelling luminescence with time-resolved single photon detection. We generate excitons and trions in single Zinc Phthalocyanine (ZnPc) molecules on NaCl/Ag(111), and trace the evolution of the system in the picosecond range. We explore the dependence of effective lifetimes on bias voltage and describe the conversion mechanism from neutral excitons to trions, via charge capture, as the primary pathway to trion formation. We corroborate the dynamics of the system by a causally deterministic four-state model.
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Affiliation(s)
- Jiří Doležal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, CZ16200 Praha 6, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ12116 Praha 2, Czech Republic
| | - Sofia Canola
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, CZ16200 Praha 6, Czech Republic
| | - Pablo Merino
- 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
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, CZ16200 Praha 6, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, CZ78371 Olomouc, Czech Republic
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12
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Doležal J, Mutombo P, Nachtigallová D, Jelínek P, Merino P, Švec M. Mechano-Optical Switching of a Single Molecule with Doublet Emission. ACS NANO 2020; 14:8931-8938. [PMID: 32539338 PMCID: PMC7116298 DOI: 10.1021/acsnano.0c03730] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
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.
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Affiliation(s)
- Jiří Doležal
- Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
| | - Pingo Mutombo
- Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic
- Department of Petrochemistry and Refining, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Dana Nachtigallová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Praha, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, 78371 Olomouc, Czech Republic
| | - Pavel Jelínek
- Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, 78371 Olomouc, Czech Republic
| | - Pablo Merino
- 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
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, 78371 Olomouc, Czech Republic
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