1
|
Seabury AG, Khodabocus AJ, Kogan IM, Hoy GR, DeSalvo GA, Wustholz KL. Blinking characteristics of organic fluorophores for blink-based multiplexing. Commun Chem 2024; 7:18. [PMID: 38280979 PMCID: PMC10821931 DOI: 10.1038/s42004-024-01106-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/12/2024] [Indexed: 01/29/2024] Open
Abstract
Single-molecule fluorescence experiments have transformed our understanding of complex materials and biological systems. Whether single molecules are used to report on their nano-environment or provide for localization, understanding their blinking dynamics (i.e., stochastic fluctuations in emission intensity under continuous illumination) is paramount. We recently demonstrated another use for blinking dynamics called blink-based multiplexing (BBM), where individual emitters are classified using a single excitation laser based on blinking dynamics, rather than color. This study elucidates the structure-activity relationships governing BBM performance in a series of model rhodamine, BODIPY, and anthraquinone fluorophores that undergo different photo-physical and-chemical processes during blinking. Change point detection and multinomial logistic regression analyses show that BBM can leverage spectral fluctuations, electron and proton transfer kinetics, as well as photostability for molecular classification-even within the context of a shared blinking mechanism. In doing so, we demonstrate two- and three-color BBM with ≥ 93% accuracy using spectrally-overlapped fluorophores.
Collapse
Affiliation(s)
| | | | | | - Grayson R Hoy
- Chemistry Department, William & Mary, Williamsburg, VA, USA
| | | | | |
Collapse
|
2
|
Alves PU, Guilhabert BJE, McPhillimy JR, Jevtics D, Strain MJ, Hejda M, Cameron D, Edwards PR, Martin RW, Dawson MD, Laurand N. Waveguide-Integrated Colloidal Nanocrystal Supraparticle Lasers. ACS APPLIED OPTICAL MATERIALS 2023; 1:1836-1846. [PMID: 38037651 PMCID: PMC10683367 DOI: 10.1021/acsaom.3c00312] [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: 09/04/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 12/02/2023]
Abstract
Supraparticle (SP) microlasers fabricated by the self-assembly of colloidal nanocrystals have great potential as coherent optical sources for integrated photonics. However, their deterministic placement for integration with other photonic elements remains an unsolved challenge. In this work, we demonstrate the manipulation and printing of individual SP microlasers, laying the foundation for their use in more complex photonic integrated circuits. We fabricate CdSxSe1-x/ZnS colloidal quantum dot (CQD) SPs with diameters from 4 to 20 μm and Q-factors of approximately 300 via an oil-in-water self-assembly process. Under a subnanosecond-pulse optical excitation at 532 nm, the laser threshold is reached at an average number of excitons per CQD of 2.6, with modes oscillating between 625 and 655 nm. Microtransfer printing is used to pick up individual CQD SPs from an initial substrate and move them to a different one without affecting their capability for lasing. As a proof of concept, a CQD SP is printed on the side of an SU-8 waveguide, and its modes are successfully coupled to the waveguide.
Collapse
Affiliation(s)
- Pedro Urbano Alves
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Benoit J. E. Guilhabert
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - John R. McPhillimy
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Dimitars Jevtics
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Michael J. Strain
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Matěj Hejda
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Douglas Cameron
- Department
of Physics, SUPA, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, U.K.
| | - Paul R. Edwards
- Department
of Physics, SUPA, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, U.K.
| | - Robert W. Martin
- Department
of Physics, SUPA, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, U.K.
| | - Martin D. Dawson
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| | - Nicolas Laurand
- Institute
of Photonics, Department of Physics, SUPA, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, U.K.
| |
Collapse
|
3
|
Long T, Cao J, Jiang ZJ. Predictable spectroscopic properties of type-II ZnTe/CdSe nanocrystals and electron/hole quenching. Phys Chem Chem Phys 2019; 21:5824-5833. [PMID: 30806432 DOI: 10.1039/c9cp00026g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The spectroscopic properties of core/shell structured ZnTe/CdSe nanocrystals (NCs) have been systematically studied. By varying the ZnTe core diameter and the CdSe shell thickness, the absorption onset and the photoluminescence peak position of the ZnTe/CdSe NCs can be readily tuned over a wide range. The theoretical model based on an effective mass approximation demonstrates that the ZnTe/CdSe NCs have type II carrier localization in which the photoexcited electrons and holes are spatially separated and confined in the shell and core, respectively. The energetics of the conduction and valence bands and the bandgaps of the ZnTe/CdSe NCs are accurately predicted. The photoluminescent experiments show that electron quenchers having a large energy difference between their reduction potential and the lowest conduction band edge of the ZnTe/CdSe nanocrystals can completely quench the luminescence. Electron acceptors having a reduction potential only slightly below the conduction band edge partially quench the photoluminescence of the nanocrystals. In this case, the extent of quenching depends upon the thickness of the shell and the energy difference. Despite the confinement of photoexcited holes in the core, the photoluminescence could be still quenched by adsorbed hole quenchers. The extent of hole quenching depends upon the core size, the shell thickness and the oxidation potential of the quenchers. Basically, an increase in the core size and the shell thickness may lead to a decrease in the extent of hole quenching. The work presented here is of great interest since it can be extended to understand the spectroscopic properties and photoluminescence quenching behaviors of other core/shell semiconductor NCs.
Collapse
Affiliation(s)
- Tongqing Long
- Guangzhou Key Laboratory for Surface Chemistry of Energy Materials, New Energy Research Institute, College of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
| | | | | |
Collapse
|
4
|
Stupak AP, Blaudeck T, Zenkevich EI, Krause S, von Borczyskowski C. The nature of non-FRET photoluminescence quenching in nanoassemblies from semiconductor quantum dots and dye molecules. Phys Chem Chem Phys 2018; 20:18579-18600. [PMID: 29953143 DOI: 10.1039/c8cp02846j] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nanoassemblies formed via self-assembly based on colloidal CdSe quantum dots (QDs) and porphyrin (H2P) dye molecules show Fluorescence Resonant Energy Transfer (FRET) and non-FRET quenching of QD photoluminescence (PL). We present a procedure to unravel and quantify these two relaxation pathways via dynamic and static PL quenching experiments. Accordingly, FRET amounts at maximum to 10% of the total quenching efficiency. Since the degree of ligand coverage is inhomogeneously distributed across the QD ensemble PL quantum yields vary broadly. The attachment of H2P molecules occurs preferentially to those QDs with low ligand coverage. Along with that, nanoassembly formation deviates strongly from Poisson statistics. Like FRET, non-FRET depends on the QD size. We assign non-FRET quenching to the formation of specific new Cd2+ trap states following depletion of several ligands by the spacious dye molecules. While FRET follows quantitatively the Förster model, non-FRET appears on time scales of 1-3 ns in new and enhanced non-radiative near-band-edge QD PL decay channels caused by a trapping of the electrons in long-lived intra-gap states which then manifests itself in a subsequent weak PL emission. We assign the related intra-band emission to a recombination of deep-trap electrons and shallow-trap holes.
Collapse
Affiliation(s)
- Aleksander P Stupak
- B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Prospect Nezavisimosti 70, 220072 Minsk, Belarus
| | | | | | | | | |
Collapse
|
5
|
Adam V, Vaculovicova M. Capillary electrophoresis and nanomaterials - Part I: Capillary electrophoresis of nanomaterials. Electrophoresis 2017; 38:2389-2404. [DOI: 10.1002/elps.201700097] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/02/2017] [Accepted: 06/22/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Vojtech Adam
- Department of Chemistry and Biochemistry; Mendel University in Brno; Brno Czech Republic
- Central European Institute of Technology; Brno University of Technology; Brno Czech Republic
| | - Marketa Vaculovicova
- Department of Chemistry and Biochemistry; Mendel University in Brno; Brno Czech Republic
- Central European Institute of Technology; Brno University of Technology; Brno Czech Republic
| |
Collapse
|
6
|
Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
Collapse
Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
| |
Collapse
|
7
|
Demchenko AP, Dekaliuk MO. The origin of emissive states of carbon nanoparticles derived from ensemble-averaged and single-molecular studies. NANOSCALE 2016; 8:14057-14069. [PMID: 27399599 DOI: 10.1039/c6nr02669a] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
At present, there is no consensus understanding on the origin of photoluminescence of carbon nanoparticles, particularly the so-called carbon dots. Providing comparative analysis of spectroscopic studies in solution and on a single-molecular level, we demonstrate that these particles behave collectively as fixed single dipoles and probably are the quantum emitter entities. Their spectral and lifetime heterogeneity in solutions is explained by variation of the local chemical environment within and around luminescence centers. Hence, the carbon dots possess a unique hybrid combination of fluorescence properties peculiar to dye molecules, their conjugates and semiconductor nanocrystals. It is proposed that their optical properties are due to generation of H-aggregate-type excitonic states with their coherence spreading over the whole nanoparticles.
Collapse
Affiliation(s)
- Alexander P Demchenko
- A. V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Leontovicha street 9, Kiev, 01601, Ukraine.
| | | |
Collapse
|
8
|
Shchukina AL, Eremchev IY, Naumov AV. Looking at a blinking quantum emitter through time slots: the effect of blind times. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032102. [PMID: 26465421 DOI: 10.1103/physreve.92.032102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Indexed: 06/05/2023]
Abstract
Most experimental observations of physical processes are naturally accompanied by "blind" ("dead") times, which in principle can distort the result of measurements. Here we analyze how the presence of blind times in measurements changes the measured statistics of blinking fluorescence of single quantum dots. We show that information can be extracted even for blinking processes with characteristic times longer than both blind times and time slots between them.
Collapse
Affiliation(s)
- A L Shchukina
- Center of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
| | - I Yu Eremchev
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
| | - A V Naumov
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
- Moscow State Pedagogical University, 119991 Moscow, Russia
| |
Collapse
|
9
|
New tools for elucidating the environmental origins of single molecule photoluminescence intermittency. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
10
|
Zenkevich E, Stupak A, Göhler C, Krasselt C, von Borczyskowski C. Tuning electronic states of a CdSe/ZnS quantum dot by only one functional dye molecule. ACS NANO 2015; 9:2886-2903. [PMID: 25703788 DOI: 10.1021/nn506941c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Self-assembly of only one functionalized porphyrin dye molecule with one CdSe/ZnS quantum dot (QD) not only modifies the photoluminescence (PL) intensity but also creates a few energetically clearly distinguishable electronic states, opening additional effective relaxation pathways. The related energy modifications are in the range of 10-30 meV and show a pronounced sensitivity to the specific nature of the respective dye. We assign the emerging energies to surface states. Time-resolved PL spectroscopy in combination with spectral deconvolution reveals that surface properties of QDs are a complex interplay of the nature of the dye molecule and the topography of the ligand layer across a temperature range from 77 to 290 K. This includes a kind of phase transition of trioctylphosphine oxide ligands, switching the nature of surface states observed below and above the phase transition temperature. Most importantly, our findings can be closely related to recent calculations of ligand-induced modifications of surface states of QDs. The identification of the optical properties emerged from a combination of spectroscopy on single QDs and QDs in an ensemble.
Collapse
Affiliation(s)
- Eduard Zenkevich
- †Department of Information Technologies and Robotics, National Technical University of Belarus, Nezavisimosti Ave., 65, 220013 Minsk, Belarus
| | - Aleksander Stupak
- ‡B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nezavisimosti Ave., 70, 220072 Minsk, Belarus
| | - Clemens Göhler
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
| | - Cornelius Krasselt
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
| | | |
Collapse
|
11
|
Hess CM, Rudolph AR, Reid PJ. Imaging the Effects of Annealing on the Polymorphic Phases of Poly(vinylidene fluoride). J Phys Chem B 2015; 119:4127-32. [DOI: 10.1021/jp512486n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Chelsea M. Hess
- Department
of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Angela R. Rudolph
- Department
of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Philip J. Reid
- Department
of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| |
Collapse
|
12
|
Hess CM, Riley EA, Reid PJ. Dielectric dependence of single-molecule photoluminescence intermittency: nile red in poly(vinylidene fluoride). J Phys Chem B 2014; 118:8905-13. [PMID: 24995904 PMCID: PMC4372109 DOI: 10.1021/jp505874m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
The
dependence of single-molecule photoluminescence intermittency
(PI) or “blinking” on the local dielectric constant
(ε) is examined for nile red (NR) in thin films of poly(vinylidene
fluoride) (PVDF). In previous studies, variation of the local dielectric
constant was accomplished by studying luminophores in chemically and
structurally different hosts. In contrast, the NR/PVDF guest–host
pair allows for the investigation of PI as a function of ε while
keeping the chemical composition of both the luminophore and host
unchanged. The solvatochromic properties of NR are used to measure
the local ε, while fluctuations in NR emission intensity over
time provide a measure of the PI. PVDF is an ideal host for this study
because it provides submicron-sized dielectric domains that vary from
nonpolar (ε ≈ 2) to very polar (ε ≈ 70).
The results presented here demonstrate that the local dielectric environment
can have a pronounced effect on PI. We find that the NR emissive events
increase 5-fold with an increase in ε from 2.2 to 74. A complex
dependence on ε is also observed for NR nonemissive event durations,
initially increasing as ε increases from 2.2 to 3.4 but decreasing
in duration with further increase in ε. The variation in emissive
event durations with ε is reproduced using a photoinduced electron-transfer
model involving electron transfer from NR to PVDF. In addition, an
increase in NR photostability with an increase in ε is observed,
suggesting that the dielectric environment plays an important role
in defining the photostability of NR in PVDF.
Collapse
Affiliation(s)
- Chelsea M Hess
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | | | | |
Collapse
|
13
|
Xu X. Surface recombination and charged exciton in nanocrystal quantum dots on photonic crystals under two-photon excitation. Sci Rep 2014; 4:5039. [PMID: 24902925 PMCID: PMC4047539 DOI: 10.1038/srep05039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 04/14/2014] [Indexed: 12/20/2022] Open
Abstract
In this study, the two-photon excited fluorescence spectra from cadmium selenide quantum dots (QDs) on a silicon nitride photonic crystal (PhC) membrane under femtosecond laser irradiation were investigated. These spectra can be fit to a tri-Gaussian function in which one component is negative in amplitude, and in which the Gaussian components with positive amplitude are assigned to exciton emission and charged-exciton emission and that with negative amplitude is assigned to absorption from surface recombination. The photonic crystal enhance the charged-exciton emission and exciton emission and, at the same time, also the absorption from surface recombination. Both the charged-exciton emission and the surface recombination are related to Auger recombination; therefore, the photonic crystal controls both radiative recombination and non-radiative recombination. The asymmetries of the two-photon excited fluorescence spectra are due to not only the location of the resonant guide mode of the PhC slab but also the enhancement of the absorption from surface recombination by PhC.
Collapse
Affiliation(s)
- Xingsheng Xu
- State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| |
Collapse
|
14
|
Schmidt R, Krasselt C, Göhler C, von Borczyskowski C. The fluorescence intermittency for quantum dots is not power-law distributed: a luminescence intensity resolved approach. ACS NANO 2014; 8:3506-3521. [PMID: 24580107 DOI: 10.1021/nn406562a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The photoluminescence (PL) of single emitters like semiconductor quantum dots (QDs) shows PL intermittency, often called blinking. We explore the PL intensities of single CdSe/ZnS QDs in polystyrene (PS), on polyvenylalcohol (PVA), and on silicon oxide (SiOx) by the change-point analysis (CPA). By this, we relate results from the macrotime (sub-ms to 1000 s) and the microtime (0.1-100 ns) range to discrete PL intensities. We conclude that the intensity selected "on"-times in the ms range correspond to only a few (discrete) switching times, while the PL decays in the ns range are multiexponential even with respect to the same selected PL intensity. Both types of relaxation processes depend systematically on the PL intensity in course of a blinking time trace. The overall distribution of on-times does not follow a power law contrary to what has often been reported but can be compiled into 3-4 characteristic on-times. The results can be explained by the recently suggested multiple recombination centers model. Additionally, we can identify a well-defined QD state with a very low PL intensity above the noise level, which we assign to the strongly quenched exciton state. We describe our findings by a model of a hierarchical sequence of hole and electron trapping. Blinking events are the consequence of slow switching processes among these states and depend on the physicochemical properties of the heterogeneous nanointerface of the QDs.
Collapse
Affiliation(s)
- Robert Schmidt
- Institute of Physics, Optical Spectroscopy and Molecular Physics, Centre for Nanostructured Materials and Analytics (nanoMA), Technische Universität Chemnitz , 09107 Chemnitz, Germany
| | | | | | | |
Collapse
|
15
|
Thomsson D, Camacho R, Tian Y, Yadav D, Sforazzini G, Anderson HL, Scheblykin IG. Cyclodextrin insulation prevents static quenching of conjugated polymer fluorescence at the single molecule level. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:2619-2627. [PMID: 23463732 DOI: 10.1002/smll.201203272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Indexed: 06/01/2023]
Abstract
Conjugated polymers (CPs) are promising materials for fluorescence imaging application. However, a significant problem in this field is the unexplained abnormally low fluorescence brightness (or number of fluorescence photons detected per one excitation photon) exhibited by most of CP single chains in solid polymer hosts. Here it is shown that this detrimental effect can be fully avoided for short chains of polyfluorene-bis-vinylphenylene (PFBV) embedded in a host polymer matrix of PMMA, if the conjugated backbone is insulated by cyclodextrin rings to form a polyrotaxane (PFBV-Rtx). Fluorescence kinetics and quantum yields are measured for the polymers in liquid solutions, pristine films, and solid PMMA blends. The fluorescence brightness of PFBV-Rtx single chains dispersed in a solid PMMA is very close to that expected for a chain with 100% fluorescence quantum yield, while the unprotected PFBV chains of the same length possess 4 times lower brightness. Despite this, the fluorescence decay kinetics are the same for both polymers, suggesting the presence of static or ultrafast fluorescence quenching in the unprotected polymer. About 80% of an unprotected PFBV chain is estimated to be completely quenched. The hypothesis is that the cyclodextrin rings prevent the quenching by working as 'bumpers' reducing the mechanical forces applied by the host polymer to the conjugated backbone and help retaining its conformational freedom. While providing a recipe for making CP fluorescence bright at the single-molecule level, these results identify a lack of fundamental understanding in the community of the influence of the environment on excited states in conjugated materials.
Collapse
Affiliation(s)
- Daniel Thomsson
- Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
| | | | | | | | | | | | | |
Collapse
|