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Karak P, Manna P, Banerjee A, Ruud K, Chakrabarti S. Reverse Intersystem Crossing Dynamics in Vibronically Modulated Inverted Singlet-Triplet Gap System: A Wigner Phase Space Study. J Phys Chem Lett 2024; 15:7603-7609. [PMID: 39028946 DOI: 10.1021/acs.jpclett.4c01437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2024]
Abstract
We inspect the origin of the inverted singlet-triplet gap (INVEST) and slow change in the reverse intersystem crossing (rISC) rate with temperature, as recently observed. A Wigner phase space study reveals that, though INVEST is found at equilibrium geometry, variation in the exchange interaction and the doubles-excitation for other geometries in the harmonic region leads to non-INVEST behavior. This highlights the importance of nuclear degrees of freedom for the INVEST phenomenon, and in this case, geometric puckering of the studied molecule determines INVEST and the associated rISC dynamics.
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Affiliation(s)
- Pijush Karak
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, West Bengal, India
| | - Pradipta Manna
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, West Bengal, India
| | - Ambar Banerjee
- Research Institute for Sustainable Energy (RISE), TCG Centres for Research and Education in Science and Technology (TCG-CREST), Kolkata 700091, India
| | - Kenneth Ruud
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Tromsø - The Arctic University of Norway, 9037 Tromsø, Norway
- Norwegian Defence Research Establishment, P.O. Box 25, 2027 Kjeller, Norway
| | - Swapan Chakrabarti
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, West Bengal, India
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Van der Zee B, Li Y, Wetzelaer GJAH, Blom PWM. Efficiency of Polymer Light-Emitting Diodes: A Perspective. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108887. [PMID: 34786784 DOI: 10.1002/adma.202108887] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Indexed: 06/13/2023]
Abstract
The various contributions to the external quantum efficiency (EQE) of polymer light-emitting diodes (PLEDs) are discussed. The EQE of an organic light-emitting diode is governed by a number of parameters, such as the electrical efficiency, the photoluminescence quantum yield (PLQY), the optical outcoupling efficiency and the spin statistics for singlet exciton generation. In the last decade, the electrical efficiency has been determined from a numerical PLED device model. More recently, an optical model to simulate the fraction of photons outcoupled to air for PLEDs with a broad recombination zone has been developed. Together with the directly measured PLQY, the EQE of a PLED can then be estimated. However, it has been observed that the measured EQEs of fluorescent PLEDs, including the model system super-yellow poly(p-phenylene vinylene) (SY-PPV) often exceed the expected values. To solve this discrepancy, it is demonstrate that the electrical PLED model has to be expanded by the inclusion of triplet-triplet annihilation (TTA), which is shown to be responsible for a substantial EQE enhancement. Experimentally, it is obtained that TTA contributes to a singlet-exciton generation efficiency of ≈40% in SY-PPV PLEDs, giving rise to an EQE of ≈4% instead of the expected value of 2.5%.
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Affiliation(s)
- Bas Van der Zee
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | - Yungui Li
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | | | - Paul W M Blom
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
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Research on structural, spectral (IR, UV-Vis, 1H- and 13C-NMR) and light emitting properties of triisocyano-based trinuclear Au(I) complexes. CHEMICAL PAPERS 2020. [DOI: 10.1007/s11696-020-01088-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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4
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Direct monitoring of bias-dependent variations in the exciton formation ratio of working organic light emitting diodes. Sci Rep 2015; 5:15533. [PMID: 26487499 PMCID: PMC4614446 DOI: 10.1038/srep15533] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 09/28/2015] [Indexed: 11/20/2022] Open
Abstract
In typical operation of organic light emitting diodes (OLEDs), excitons are assumed to generate with a ratio of 1:3 for singlet and triplet excitons, respectively, based on a simple spin statistics model. This assumption has been used in designing efficient OLEDs. Despite the larger generation ratio of triplet excitons, physical properties of fluorescent OLEDs are usually evaluated only through the electroluminescence (EL) intensity from singlets and the behaviors of triplets during the LED operation are virtually black-boxed, because the triplets are mostly non-emissive. Here, we employ transient spectroscopy combined with LED-operation for directly monitoring the non-emissive triplets of working OLEDs. The spectroscopic techniques are performed simultaneously with EL- and current measurements under various operation biases. The simultaneous measurements reveal that the relative formation ratio of singlet-to-triplet excitons dramatically changes with the magnitude of bias. The measurements also show that the generation efficiency of singlets scales with the bias, whereas that of triplets is nearly bias-independent. These features of the formation ratio and efficiency are compatibly explained by considering the yield of intersystem crossing and the energy separation of excitons from electron-hole pairs. The obtained findings via the spectroscopic measurements enable prediction of the formation pathways in OLEDs.
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Wang L, Li Y, Zhang Y, He H, Zhang J. Dual emission behavior of phenyleneethynylene gold(I) complexes dictated by intersystem crossing: a theoretical perspective. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 137:259-266. [PMID: 25222321 DOI: 10.1016/j.saa.2014.08.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/06/2014] [Accepted: 08/23/2014] [Indexed: 06/03/2023]
Abstract
In commonly studied gold(I) complexes with oligo (o-, p-, or m-phenyleneethynylene) (PE) ligands, an intriguing photophysical behavior is dual emission composed of fluorescence from S1 and phosphorescence from T1 which is dictated by effective intersystem crossing (ISC) process. In order to explore the salient photodynamics of such oligo-PE gold(I) complexes effectively, we have deliberately chosen three model complexes, namely, Ph-C≡C-Au(PMe3) (1a') and Ph-C≡C-(1,m)C6H4-C≡C-Au(PMe3) (m=4, 2a'; m=3, 3a') in place of the real system. Firstly, electronic structure methods based on DFT and TD-DFT are utilized to perform optimization calculations for the ground- and lowest-lying excited states, respectively. Next, basic photophysical properties including absorption and emission spectra are investigated by TD-DFT under the optimized geometries. Besides, on the basis of the electronic spectra herein, we succeed in searching for surface intersections as the minima on the seam of singlet-triplet surface crossings (SCs) at the CASSCF level of theory. By integration of the results available, the process of delayed fluorescence of triplet-triplet annihilation (TTA) and phosphorescence was displayed in detail with SCs playing the lead in monitoring the ISC.
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Affiliation(s)
- Li Wang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Yuanyuan Li
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Yanxin Zhang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China
| | - Hongqing He
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan 430071, PR China
| | - Jinglai Zhang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China.
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Gwinner MC, Kabra D, Roberts M, Brenner TJK, Wallikewitz BH, McNeill CR, Friend RH, Sirringhaus H. Highly efficient single-layer polymer ambipolar light-emitting field-effect transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2728-34. [PMID: 22513713 DOI: 10.1002/adma.201104602] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/06/2012] [Indexed: 05/12/2023]
Abstract
Single-layer polymer light-emitting field-effect transistors (LEFETs) that yield EQEs of >8% and luminance efficiencies >28 cd A(-1) are demonstrated. These values are the highest reported for LEFETs and amongst the highest values for fluorescent OLEDs. Due to the electrostatics of the ambipolar LEFET channel, LEFETs provide an inherent advantage over OLEDs in terms of minimizing exciton-polaron quenching.
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Lu W, Kwok WM, Ma C, Chan CTL, Zhu MX, Che CM. Organic triplet excited states of gold(I) complexes with oligo(o- or m-phenyleneethynylene) ligands: conjunction of steady-state and time-resolved spectroscopic studies on exciton delocalization and emission pathways. J Am Chem Soc 2011; 133:14120-35. [PMID: 21846130 DOI: 10.1021/ja205831v] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A series of mononuclear and binuclear gold(I) complexes containing oligo(o- or m-phenyleneethynylene) (PE) ligands, namely [PhC≡C(C(6)H(4)-1,2-C≡C)(n-1)Au(PCy(3))] (n = 2-4, 4a-c), [μ-{C≡C-(1,2-C(6)H(4)C≡C)(n)}{Au(PCy(3))}(2)] (n = 1-6, 8, 5a-g), [PhC≡C(C(6)H(4)-1,3-C≡C)(n-1)Au(PCy(3))] (n = 2-4, 6a-c), and [μ-{C≡C-(1,3-C(6)H(4)C≡C)(n)}{Au(PCy(3))}(2)] (n = 1, 2, 7a,b), were synthesized and structurally characterized. Extensive spectroscopic measurements have been performed by applying combined methods of femtosecond transient absorption (fs-TA), fs time-resolved fluorescence (fs-TRF), and nanosecond time-resolved emission (ns-TRE) coupled with steady-state absorption and emission spectroscopy at both ambient and low (77 K) temperatures to directly probe the temporal evolution of the excited states and to determine the dynamics and spectral signatures for the involved singlet (S(1)) and triplet (T(1)) excited states. The results reveal that S(1) and T(1) both feature ligand-centered electronic transitions with ππ* character associated with the phenyl and acetylene moieties. The (3)ππ* emission of the PE ligands is switched on by the attachment of [Au(PCy(3))](+) fragment(s) due to the heavy-atom effect. T(1)((3)ππ*) was found to form with nearly unity efficiency through intersystem crossing (ISC) from S(1)((1)ππ*). The ISC time constants were determined to be ∼50, 35, and 40 ps for 4b and 6a,b, respectively. Dual emission composed of fluorescence from S(1) and phosphorescence from T(1) were observed for most of the complexes except 5a and 7a, where only phosphorescence was found. The fluorescence at ambient temperature is accounted for by both the short-lived prompt fluorescence (PF) and long-lived delayed fluorescence (DF, lifetime on microsecond time scale). Explicit evidence was presented for a triplet-triplet annihilation mechanism for the generation of DF. Ligand length and substitution-dependent dynamics of T(1) are the key factors governing the dual emission character of the complexes. By extrapolation from the plot of emission energy against the PE chain length of the [Au(PCy(3))](+) complexes with oligo(o-PE) or oligo(m-PE) ligands, the triplet emission energies were estimated to be ∼530 and ∼470 nm for poly(o-PE) and poly(m-PE), respectively. Additionally, we assign the unusual red shifts of 983 cm(-1) from [PhC≡CAu(PCy(3))] (1) to [μ-{1,3-(C≡C)(2)C(6)H(4)}{Au(PCy(3))}(2)] (7a) and 462 cm(-1) from 7a to [μ(3)-{1,3,5-(C≡C)(3)C(6)H(3)}{Au(PCy(3))}(3)] (8) in the phosphorescence energies to excitonic coupling interactions between the C≡CAu(PCy(3)) arms in the triplet excited states. These complexes, together with those previously reported [Au(PCy(3))](+) complexes containing oligo(p-PE) ligands ( J. Am. Chem. Soc. 2002 , 124 , 14696 - 14706 ), form a collection of oligo(phenyleneethynylene) complexes exhibiting organic triplet emission in solution under ambient conditions. The remarkable feature of these complexes in exhibiting TTA prompted DF in conjunction with high formation efficiency of T(1)((3)ππ*) affords an opportunity for emission spectra to cover a wide range of wavelengths. This may have implication in the development of PE-based molecular materials for future optical applications.
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Affiliation(s)
- Wei Lu
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, Department of Chemistry, The University of Hong Kong, People's Republic of China
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8
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Howard IA, Hodgkiss JM, Zhang X, Kirov KR, Bronstein HA, Williams CK, Friend RH, Westenhoff S, Greenham NC. Charge Recombination and Exciton Annihilation Reactions in Conjugated Polymer Blends. J Am Chem Soc 2009; 132:328-35. [DOI: 10.1021/ja908046h] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ian A. Howard
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Justin M. Hodgkiss
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Xinping Zhang
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Kiril R. Kirov
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Hugo A. Bronstein
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Charlotte K. Williams
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Richard H. Friend
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Sebastian Westenhoff
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Neil C. Greenham
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom, and Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
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9
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Li S, Tong GP, George TF. Radiative decay of singlet excitons and carrier-fusion-induced electroluminescence enhancement of polymer light-emitting diodes. J Phys Chem B 2009; 113:15231-6. [PMID: 19863090 DOI: 10.1021/jp907886n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
During the radiative decay of singlet excitons in polymer light-emitting diodes (PLEDs), the newly developed molecule dynamics not only describes the evolution of the lattice distortion of the polymer chain but also illustrates the time-dependent electron transitions and electron populations in detail. Furthermore, based on this method, it is revealed that the nonemissive triplet excitons in PLEDs become emissive through the fusion of injected positive polarons. The obtained maximum quantum efficiency is consistent with recent experimental results.
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Affiliation(s)
- Sheng Li
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
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10
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Klappenberger F, Weber-Bargioni A, Auwärter W, Marschall M, Schiffrin A, Barth JV. Temperature dependence of conformation, chemical state, and metal-directed assembly of tetrapyridyl-porphyrin on Cu(111). J Chem Phys 2008; 129:214702. [DOI: 10.1063/1.3021291] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mamatkulov M, Stauffer L, Sonnet P, Mayne AJ, Comtet G, Dujardin G. Theoretical simulations of the tip-induced configuration changes of the 4,4(')-diacetyl-p-terphenyl molecule chemisorbed on Si(001). J Chem Phys 2008; 128:244710. [PMID: 18601368 DOI: 10.1063/1.2943680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have investigated from a theoretical point of view modifications of the 4,4(')-diacetyl-p-terphenyl molecule chemisorbed on Si(001) induced by the scanning tunneling microscope (STM). In previous experiments, these modifications were observed to occur preferentially at the end of the molecule after a +4.0 V voltage pulse and at the center after a +4.5 V voltage pulse. In the framework of ab initio simulations, we have realized a systematic energetic study of the dissociative chemisorption of one, two, or three phenyl rings of the substituted p-terphenyl molecule. Charge densities were then calculated for the investigated configurations and compared to the STM topographies. Before manipulation with the STM tip, the substituted p-terphenyl molecule is preferentially adsorbed without phenyl ring dissociation, allowing a partial rotation of the central phenyl ring. Our results show that the STM induced modifications observed at the end of the molecule might originate from the dissociation of two phenyl rings (one central and one external ring), while the modifications occurring at the central part of the molecule can be interpreted as a dissociation of the two external rings.
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Affiliation(s)
- M Mamatkulov
- Laboratoire de Physique et de Spectroscopie Electronique, CNRS UMR 7014, Universite de Haute Alsace, 4 rue des Freres Lumiere, 68093 Mulhouse, France
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Difley S, Beljonne D, Van Voorhis T. On the Singlet−Triplet Splitting of Geminate Electron−Hole Pairs in Organic Semiconductors. J Am Chem Soc 2008; 130:3420-7. [DOI: 10.1021/ja076125m] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Seth Difley
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, and Laboratory for Chemistry of Novel Materials, Université de Mons-Hainaut, Place du Parc, 20, 7000 Mons, Belgium
| | - David Beljonne
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, and Laboratory for Chemistry of Novel Materials, Université de Mons-Hainaut, Place du Parc, 20, 7000 Mons, Belgium
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, and Laboratory for Chemistry of Novel Materials, Université de Mons-Hainaut, Place du Parc, 20, 7000 Mons, Belgium
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13
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Ultrahigh vacuum scanning tunneling microscope manipulation of single gold nanoislands on MoS[sub 2] for constructing planar nanointerconnects. ACTA ACUST UNITED AC 2007. [DOI: 10.1116/1.2781573] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Rothe C, King SM, Monkman AP. Direct measurement of the singlet generation yield in polymer light-emitting diodes. PHYSICAL REVIEW LETTERS 2006; 97:076602. [PMID: 17026258 DOI: 10.1103/physrevlett.97.076602] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Indexed: 05/12/2023]
Abstract
In this study, the singlet and triplet exciton generation yields of a representative blue-emitting conjugated polymer are directly compared using simultaneous optical and electrical excitation measurements. After carefully accounting for bimolecular triplet annihilation and knowing the independently measured solid state inter-system-crossing yield of the polymer, a singlet generation yield of 44% is obtained, in the working device, which is clearly in excess of the simple quantum statistical 25% limit.
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Affiliation(s)
- C Rothe
- Department of Physics, University of Durham, Durham, DH1 3LE, United Kingdom.
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Barzykin AV, Tachiya M. Stochastic Model of Photodynamics in Multichromophoric Conjugated Polymers. J Phys Chem B 2006; 110:7068-72. [PMID: 16571024 DOI: 10.1021/jp056088q] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A stochastic model of triplet exciton dynamics in multichromophoric conjugated polymers is presented and analyzed in detail, with a focus on the single molecule spectroscopy observables. The model deals with the evolution of a discrete statistical distribution of triplets in isolated polymer molecules. This approach should provide more accurate quantitative information on the dynamic processes involved, as compared to the previously used two-state model which assumes that a conjugated polymer cannot contain more than one triplet. In particular, it allows for determination of the triplet-triplet annihilation rate.
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Affiliation(s)
- A V Barzykin
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
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16
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Gesquiere AJ, Park SJ, Barbara PF. Hole-induced quenching of triplet and singlet excitons in conjugated polymers. J Am Chem Soc 2005; 127:9556-60. [PMID: 15984882 DOI: 10.1021/ja051271i] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Quantitative information on the mechanisms and rates of hole (radical cation)-induced quenching of triplet and singlet excitons in the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] has been acquired by a new technique, fluorescence-voltage time-resolved single molecule spectroscopy (FV-TR-SMS). FV-TR-SMS measures the fluorescence intensity of a single conjugated polymer molecule that is embedded in a capacitor-like device while simultaneously modulating the bias on the device and the irradiation intensity. The results demonstrate that triplet excitons are efficiently quenched by holes in conjugated polymers for hole densities >10(16) charges/cm(3), while singlet excitons are quenched with a much lower efficiency. Detailed kinetic analysis shows that the greater efficiency for quenching of triplets by holes (compared to that for singlets) is due to a >10(6) times longer exciton lifetime for triplets. In fact, the results suggest that while singlet quenching is less efficient due to a much shorter singlet lifetime, the rate constant for the quenching of singlets by holes actually exceeds that for triplets by several orders of magnitude.
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Affiliation(s)
- Andre J Gesquiere
- Center for Nano- and Molecular Science and Technology, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
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Soukiassian L, Mayne AJ, Comtet G, Hellner L, Dujardin G, Gourdon A. Selective internal manipulation of a single molecule by scanning tunneling microscopy. J Chem Phys 2005; 122:134704. [PMID: 15847486 DOI: 10.1063/1.1874972] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the adsorption of the polyaromatic molecule 1,4"-paratriphenyldimethylacetone, which we have nicknamed Trima. The originality of this linear molecule is that it was designed and synthesized to have two functionalities. First, chemisorb itself to the surface by its two ends rather like a bridge. Second, the central part of the molecule could then be rotated by injecting electrons with the tip of the scanning tunneling microscope (STM). The length of the molecule corresponds exactly to the spacing between five dimers in a row on the Si(100)-2 x 1 surface. We found that the molecule adsorbs as expected on the clean silicon surface by using complementary STM and synchrotron radiation studies. Manipulation of individual molecules with the STM tip showed selective internal modifications that were highly voltage dependent. These manipulations were found to be compatible with an electronic excitation of the pi-pi* transition of the molecule.
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Affiliation(s)
- Laetitia Soukiassian
- Laboratoire de Photophysique Moléculaire, CNRS, UPR 3361, Bâtiment 210, Université de Paris-Sud, 91405 Orsay, France
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Yin S, Chen L, Xuan P, Chen KQ, Shuai Z. Field Effect on the Singlet and Triplet Exciton Formation in Organic/Polymeric Light-Emitting Diodes. J Phys Chem B 2004. [DOI: 10.1021/jp037327h] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shiwei Yin
- Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China
| | - Liping Chen
- Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China
| | - Pengfei Xuan
- Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China
| | - Ke-Qiu Chen
- Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China
| | - Z. Shuai
- Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China
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Schott M. Comment on "Triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes". PHYSICAL REVIEW LETTERS 2004; 92:059701-059702. [PMID: 14995351 DOI: 10.1103/physrevlett.92.059701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2003] [Indexed: 05/24/2023]
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Osterbacka R. Comment on "triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes". PHYSICAL REVIEW LETTERS 2003; 91:219701-219703. [PMID: 14683344 DOI: 10.1103/physrevlett.91.219701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2003] [Indexed: 05/24/2023]
Affiliation(s)
- R Osterbacka
- Department of Physics Abo Akademi University Porthansgatan 3 FIN-20500 Turku, Finland.
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Dhoot AS, Greenham NC. Comment on "triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes". PHYSICAL REVIEW LETTERS 2003; 91:219702-219703. [PMID: 14683345 DOI: 10.1103/physrevlett.91.219702] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2003] [Indexed: 05/24/2023]
Affiliation(s)
- A S Dhoot
- Cavendish Laboratory Madingley Road Cambridge, CB3 0HE, United Kingdom
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Shuai Z, Yin S, Chen L, Ye A, Beljonne D, Brédas JL. Theoretical Investigation of the Spin-dependent Exciton Formation Rates in Polymeric Light-emitting Diodes. J CHIN CHEM SOC-TAIP 2003. [DOI: 10.1002/jccs.200300099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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