1,582 results on '"tetracene"'
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2. Simulation for the Effect of Singlet Fission Mechanism of Tetracene on Perovskite Solar Cell
- Author
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Toan Ngoc Le and Lin Liu
- Subjects
solar cell ,Control and Optimization ,Renewable Energy, Sustainability and the Environment ,singlet fission ,Energy Engineering and Power Technology ,Building and Construction ,Electrical and Electronic Engineering ,renewable ,stability ,Engineering (miscellaneous) ,perovskite ,Energy (miscellaneous) ,tetracene - Abstract
The perovskite solar cell has recently gained momentum within the renewable energy industry due to its unique advantages such as high efficiency and cost-effectiveness. However, its instability remains a challenge to its commercialization. In this study, a singlet fission material, namely tetracene, is coupled with the perovskite solar cell to simulate its effect on the solar cell. The amount of thermalization loss and the temperature of the perovskite layer are simulated and analyzed to indicate the mechanism’s effectiveness. We found that coupling the tetracene layer resulted in a drastic reduction in thermalization loss and a slower slope in perovskite layer temperature. This indicates that tetracene would stabilize the perovskite solar cell and minimize its potential losses. The thickness of the solar cell layers is also analyzed as a factor of the overall effectiveness of singlet fission on solar cells.
- Published
- 2023
- Full Text
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3. Singlet Exciton Dynamics of Perylene Diimide- and Tetracene-Based Hetero/Homogeneous Substrates via an Ab Initio Kinetic Monte Carlo Model
- Author
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Salvy P. Russo, Jared H. Cole, Anjay Manian, Francesco Campaioli, and Igor Lyskov
- Subjects
Materials science ,Singlet exciton ,Ab initio ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Tetracene ,chemistry ,Chemical physics ,Diimide ,Homogeneous ,Kinetic Monte Carlo ,Physical and Theoretical Chemistry ,Perylene - Published
- 2021
4. Revealing the Contest between Triplet–Triplet Exchange and Triplet–Triplet Energy Transfer Coupling in Correlated Triplet Pair States in Singlet Fission
- Author
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Nicholas J. Mayhall and Vibin Abraham
- Subjects
Physics ,Exchange interaction ,Ab initio ,Chromophore ,Molecular physics ,Dissociation (chemistry) ,chemistry.chemical_compound ,Tetracene ,chemistry ,Singlet fission ,General Materials Science ,Physical and Theoretical Chemistry ,Spin (physics) ,Biexciton - Abstract
Understanding the separation of the correlated triplet pair state 1(TT) intermediate is critical for leveraging singlet fission to improve solar cell efficiency. This separation mechanism is dominated by two key interactions: (i) the exchange interaction (K) between the triplets which leads to the spin splitting of the biexciton state into 1(TT),3(TT) and 5(TT) states, and (ii) the triplet-triplet energy transfer integral (t) which enables the formation of the spatially separated (but still spin entangled) state 1(T···T). We develop a simple ab initio technique to compute both the biexciton exchange (K) and biexciton transfer coupling. Our key findings reveal new conditions for successful correlated triplet pair state dissociation. The biexciton exchange interaction needs to be ferromagnetic or negligible to the triplet energy transfer for favorable dissociation. We also explore the effect of chromophore packing to reveal geometries where these conditions are achieved for tetracene.
- Published
- 2021
5. Ultrafast Singlet Energy Transfer before Fission in a Tetracene/WSe2 Type II Hybrid Heterostructure
- Author
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Zukun Wang, Yanping Liu, Yujie Li, Qiaohui Zhou, Haiming Zhu, Weijian Tao, and Lei Ye
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Materials science ,Fission ,business.industry ,Exciton ,Heterojunction ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Molecular physics ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Tetracene ,Semiconductor ,chemistry ,Monolayer ,Singlet fission ,General Materials Science ,Singlet state ,Physical and Theoretical Chemistry ,business - Abstract
Hybrid heterostructures comprising organic and two-dimensional (2D) layered semiconductors hold great promise for light harvesting and optoelectronic applications. Among them, organic materials that exhibit singlet fission (SF) in which one singlet exciton generates two triplet excitons are particularly attractive and can potentially improve the performance of the device. However, SF-enhanced devices require that SF can compete with direct energy/charge transfer from the singlet exciton. Here, we performed ultrafast spectroscopic studies on a prototypical heterostructure consisting of tetracene (Tc) and monolayer WSe2. We show a type II band alignment with 16.5 ps hole transfer from photoexcited WSe2 to tetracene and a long-lived (∼565 ps) charge separation. Importantly, we show ultrafast (∼3.4 ps) singlet exciton energy transfer from photoexcited tetracene to WSe2, prior to the slow SF process (>20 ps) in tetracene. This study raises the challenge and calls for the careful design of SF-enhanced 2D optoelectronic devices.
- Published
- 2021
6. Cycloaddition Cascades of Strained Alkynes and Oxadiazinones
- Author
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Kendall N. Houk, Evan R. Darzi, Melissa Ramirez, Neil K. Garg, and Joyann S Donaldson
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arynes ,Pericyclic reaction ,polycyclic aromatic hydrocarbons ,Organic Chemistry ,New materials ,General Medicine ,General Chemistry ,Aryne ,Article ,Catalysis ,Cycloaddition ,cycloadditions ,Pentacene ,chemistry.chemical_compound ,Tetracene ,chemistry ,Cascade ,Computational chemistry ,cyclic alkynes ,Chemical Sciences ,Density functional theory ,density functional theory - Abstract
We report a computational and experimental study of the reaction of oxadiazinones and strained alkynes to give polycyclic aromatic hydrocarbons (PAHs). The reaction proceeds by way of a pericyclic reaction cascade and leads to the formation of four new carbon-carbon bonds. Using M06-2X DFT calculations, we interrogate several mechanistic aspects of the reaction, such as why the use of non-aromatic strained alkynes can be used to access unsymmetrical PAHs, whereas the use of arynes in the methodology leads to symmetrical PAHs. In addition, experimental studies enable the rapid synthesis of new PAHs, including tetracene and pentacene scaffolds. These studies not only provide fundamental insight regarding the aforementioned cycloaddition cascades and synthetic access to PAH scaffolds, but are also expected to enable the synthesis of new materials.
- Published
- 2021
7. DFT and TD-DFT Analysis for the Modeling of Efficient Organic Light Emitting Diode (OLED)
- Author
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Shamoon Ahmad Siddiqui
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chemistry.chemical_classification ,Materials science ,Electron donor ,Time-dependent density functional theory ,Electron acceptor ,Molecular physics ,Acceptor ,chemistry.chemical_compound ,Tetracene ,chemistry ,Moiety ,Density functional theory ,Physical and Theoretical Chemistry ,Excitation - Abstract
Three donor-bridge-acceptor molecules were modeled using pentacene, tetracene, anthracene as electron donor moieties, and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) as electron acceptor moiety. The electron donor and acceptor moieties were connected with a σ bridge. The ground state geometry optimization was performed on the modeled structures, namely NTCDA-σ-pentacene, NTCDA-σ-tetracene, and NTCDA-σ-anthracene using density functional theory (DFT). After the optimization of ground-state geometry, all the geometries were re optimized with the ranging electric field in two opposite directions. One direction of the applied electric field is from donor moiety to acceptor moiety (D to A) and the other direction is from acceptor moiety to donor moiety (A to D). The natural population analysis was also performed to calculate the natural charges on donor, bridge, and acceptor moieties for all molecules. The effect of the electric field on the electronic and charge transfer properties of the three modeled molecules was deeply analyzed. The optical properties such as absorption wavelength, emission wavelength, excitation energy, emission energy, and electronic transitions were thoroughly analyzed using time-dependent density functional theory (TDDFT). It has been observed that charge transfer between donor and acceptor moieties is possible only when the electric field direction is from D to A. The outcome of the present investigation suggests that these three modeled donor-bridge-acceptor species are suitable for the possible application as organic light-emitting diodes.
- Published
- 2021
8. Controlling Exciton Propagation in Organic Crystals through Strong Coupling to Plasmonic Nanoparticle Arrays
- Author
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Anton Matthijs Berghuis, Ruth H. Tichauer, Lianne M. A. de Jong, Ilia Sokolovskii, Ping Bai, Mohammad Ramezani, Shunsuke Murai, Gerrit Groenhof, Jaime Gómez Rivas, Center for Terahertz Science and Technology Eindhoven, Surface Photonics, Photonics and Semiconductor Nanophysics, and Applied Physics and Science Education
- Subjects
Condensed Matter::Quantum Gases ,Condensed Matter::Other ,Physics::Optics ,molecular dynamics simulations ,polariton transport ,fysikaalinen kemia ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,elektronit ,kvasihiukkaset ,plasmonics ,Atomic and Molecular Physics, and Optics ,nanoparticle array ,tetracene ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,molekyylifysiikka ,plasmoniikka ,strong light-matter coupling ,eksitonit ,nanohiukkaset ,molekyylidynamiikka ,Electrical and Electronic Engineering ,Biotechnology - Abstract
Exciton transport in most organic materials is based on an incoherent hopping process between neighboring molecules. This process is very slow, setting a limit to the performance of organic optoelectronic devices. In this Article, we overcome the incoherent exciton transport by strongly coupling localized singlet excitations in a tetracene crystal to confined light modes in an array of plasmonic nanoparticles. We image the transport of the resulting exciton–polaritons in Fourier space at various distances from the excitation to directly probe their propagation length as a function of the exciton to photon fraction. Exciton–polaritons with an exciton fraction of 50% show a propagation length of 4.4 μm, which is an increase by 2 orders of magnitude compared to the singlet exciton diffusion length. This remarkable increase has been qualitatively confirmed with both finite-difference time-domain simulations and atomistic multiscale molecular dynamics simulations. Furthermore, we observe that the propagation length is modified when the dipole moment of the exciton transition is either parallel or perpendicular to the cavity field, which opens a new avenue for controlling the anisotropy of the exciton flow in organic crystals. The enhanced exciton–polariton transport reported here may contribute to the development of organic devices with lower recombination losses and improved performance. peerReviewed
- Published
- 2022
9. Parameter Extraction of High-Performance Material Based Organic Light-Emitting Transistors (OLETs)
- Author
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Brijesh Kumar and Sandeep Kumar Ojha
- Subjects
Materials science ,business.industry ,Transistor ,Organic memory ,Electronic, Optical and Magnetic Materials ,law.invention ,Threshold voltage ,Pentacene ,chemistry.chemical_compound ,Tetracene ,chemistry ,law ,OLED ,Optoelectronics ,Light emission ,business ,Low voltage - Abstract
As per industry requirement and environment conditions, the devices which made from the organic materials are chosen at present owing to their low-cost, light weight, mechanically flexible and fabricated at lower temperature. Therefore, lot of research work is take-up by the researcher globally in organic material-based devices and circuits like OTFTs, OLETs, OLEDs, OPVs emerging devices, organic memory, digital circuits, and hybrid integrated circuits (H-ICs). This research paper discusses deep investigation of OLETs, The OLET devices are depicted both optical and electrical properties in a single-device. OLET is a bi-functional device that has the light emission capability along with the switching characteristics. Where initially OLET performance is analyzed in terms of drive-current (Ids), threshold voltage (Vth), mobility (μ), and current-on-off-ratio (Ion/Ioff) by state of art Atlas Silvaco 2-D device simulator and further obtained results are compared with experimented reported data at given dimensional and electrical parameters for tetracene as OSC materials. The furthermore, transfer and output characteristics of the device is analyzed, and parameter are extracted with values of Ids, Vth, μ, and Ion/Ioff are 70 μA, 0.1 V, 4.7*10−2 cm2/Vs and 108, respectively for pentacene as OSC layer at Vgs of -3 V and Vds of -3 V. The performance of both tetracene and pentacene is compared and find that drive current of pentacene significantly higher (70 μA) in comparison to tetracene (19.5 μA). Subsequently, External Quantum Efficiency (EQE) and power analysis is also summarized in this paper that help the reliability of the OLET device. The extracted value of EQE is 4%, whereas the value of power consumption 0.06mWatt for tetracene and 0.21mWatt for pentacene. The extracted value of efficiency is 0.65% and 0.75% for tetracene and pentacene respectively at low voltage 1.5 V.
- Published
- 2021
10. 5,11‐Diazadibenzo[ hi , qr ]tetracene: Synthesis, Properties, and Reactivity toward Nucleophilic Reagents
- Author
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Keisuke Fujimoto, Satoshi Takimoto, Masami Sakamoto, Shota Masuda, Toshiyasu Inuzuka, Masaki Takahashi, and Kazutaka Sanada
- Subjects
chemistry.chemical_classification ,Nucleophilic addition ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Iodobenzene ,Alkyne ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Cycloisomerization ,Tetracene ,Nucleophile ,Moiety ,Reactivity (chemistry) - Abstract
5,11-Diazadibenzo[hi,qr]tetracene was synthesized as a new nitrogen-substituted polycyclic heteroaromatic compound by Pd-catalyzed cycloisomerization of an alkyne precursor followed by oxidative cyclization with bis(trifluoroacetoxy)iodobenzene. The substitution of imine-type nitrogen atoms significantly enhanced its electron-accepting character and facilitated the direct nucleophilic addition of arylamines under strongly basic conditions to afford the desired amino-substituted products. The introduction of amino groups induced a remarkable red-shift in their absorption spectra; the tetrasubstituted product exhibited intense near-infrared absorbing property. Furthermore, the π-electronic system, which includes a redox-active 1,4-diazabutadiene moiety, underwent reversible interconversion to its corresponding reduced form upon reduction with NaBH4 and aerobic oxidation.
- Published
- 2021
11. Singlet fission and tandem solar cells reduce thermal degradation and enhance lifespan
- Author
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Murad J. Y. Tayebjee, Timothy W. Schmidt, Nicholas J. Ekins-Daukes, Yajie Jiang, Martin A. Green, Alexander Baldacchino, Michael P. Nielsen, and Dane R. McCamey
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Materials science ,Tandem ,Renewable Energy, Sustainability and the Environment ,02 engineering and technology ,Radiation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,7. Clean energy ,Endothermic process ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Tetracene ,Operating temperature ,chemistry ,Chemical engineering ,Thermal ,Singlet fission ,Degradation (geology) ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
The operating temperature of PV modules affects the rate of degradation. We show the extent to which module operating temperature can be reduced by increasing the efficiency of the PV module via a tandem architecture or singlet Fission, the latter being of interest as a potentially endothermic process. PV modules that employ tetracene as a singlet fission material are found to be resilient against degradation since the degradation product is transparent to solar radiation.
- Published
- 2021
12. Triplet Excitons Quenching By Doublet Centers in a Nanoreactor with an External Magnetic Field
- Author
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M. G. Kucherenko and S. A. Penkov
- Subjects
Quenching ,Materials science ,Exciton ,Condensed Matter Physics ,Molecular physics ,Magnetic field ,Crystal ,Organic semiconductor ,chemistry.chemical_compound ,Tetracene ,chemistry ,Diffusion (business) ,Spin (physics) ,Spectroscopy - Abstract
The process of spin-selective quenching of a triplet (T) exciton by a fixed spin doublet (D) center in an organic semiconductor nanoparticle (anthracene, tetracene, MEH–PPV) was studied. Random walks of the T-exciton in a spherical nanovolume of a crystal or polymer globule were modeled based on the solution of the Neumann boundary diffusion condition. Time dependences of the spin-nonselective quenching rate of T-excitations were calculated for different values of geometric and diffusion parameters. Taking into account the spin dynamics of T–D-pair reagents allowed calculating magnetic field effects of T–D-quenching rate, which showed a strong influence of the nanoparticles size and initial position of the T-exciton and doublet sink on the absolute value of the effect. The obtained radial dependences of the magnetic field modulation of the quenching efficiency can be approximated by a superposition of two exponents.
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- 2021
13. Symmetry-Breaking Enhanced Herzberg–Teller Effect with Brominated Polyacenes
- Author
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Tong Zhang, Yuqin Qian, Jian Han, Yi Rao, Avetik R. Harutyunyan, Hanning Chen, and Gugang Chen
- Subjects
010304 chemical physics ,010402 general chemistry ,01 natural sciences ,Hexacene ,Molecular physics ,Molecular electronic transition ,0104 chemical sciences ,chemistry.chemical_compound ,Vibronic coupling ,Tetracene ,chemistry ,Normal mode ,0103 physical sciences ,Molecular symmetry ,Symmetry breaking ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Wave function - Abstract
Molecular symmetry is vital to the selection rule of vibrationally resolved electronic transition, particularly when the nuclear dependence of electronic wave function is explicitly treated by including Franck-Condon (FC) factor, Franck-Condon/Herzberg-Teller (FC/HT) interference, and Herzberg-Teller (HT) coupling. Our present study investigated the light absorption spectra of highly symmetric tetracene, pentacene, and hexacene molecules of point-group D2h, as well as their monobrominated derivatives with a lower Cs symmetry. It was found that the symmetry-breaking monobromination allows more vibrational normal modes and their pairs to contribute to FC/HT interference and HT coupling, respectively. Through a projection of a molecule's vibrational normal modes to its irreducible representations, a linear relationship between the FC/HT intensity to the polyacene's size was deduced alongside a quadratic dependence of the HT intensity. Both theoretically derived correlations were well justified by our numerical simulations, which also demonstrated an approximately 20% improvement on the agreement with experimental line shape if the HT theory is adopted to replace the FC approximation. Moreover, for these low-symmetry monobrominated polyacenes, the FC intensity was even weaker than its FC/HT and HT counterparts at some excitation energies, making the HT theory imperative to decipher vibronic coupling, a fundamental driving force behind numerous chemical, biological, and photophysical processes.
- Published
- 2021
14. Synthesis and Characterization of 5,5′-Bitetracene
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Hironori Kaji, Ryota Nakamura, Chihaya Adachi, Kenichi Goushi, and Masashi Mamada
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chemistry.chemical_compound ,Crystallography ,Tetracene ,chemistry ,010405 organic chemistry ,Dimer ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Single crystal ,0104 chemical sciences ,Characterization (materials science) - Abstract
A tetracene dimer, 5,5′-bitetracene (55BT), has successfully been synthesized for the first time and its structure was confirmed by X-ray single crystal analysis. The electrochemical and optical pr...
- Published
- 2021
15. Photophysics of Charge Transfer Complexes Formed by Tetracene and Strong Acceptors
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Julian Hausch, Ana M. Valencia, Caterina Cocchi, Katharina Broch, Vipilan Sivanesan, Christoph P. Theurer, Petra Tegeder, and Clemens Zeiser
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Materials science ,Charge (physics) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Tetracene ,chemistry ,Physical and Theoretical Chemistry ,Thin film ,0210 nano-technology ,Absorption (electromagnetic radiation) - Abstract
Organic charge transfer complexes (CTCs) with near-infrared absorption received growing interest in the past years, but the details of their photophysics, especially in thin films, remain largely u...
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- 2021
16. Correlated Triplet Pair Formation Activated by Geometry Relaxation in Directly Linked Tetracene Dimer (5,5′-Bitetracene)
- Author
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Chihaya Adachi, Hironori Kaji, and Katsuyuki Shizu
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Materials science ,Energy ,General Chemical Engineering ,Dimer ,Relaxation (NMR) ,Geometry ,General Chemistry ,Molecules ,Quantum mechanics ,Article ,symbols.namesake ,chemistry.chemical_compound ,Chemistry ,Oscillation ,Tetracene ,chemistry ,Mathematical methods ,Intramolecular force ,Singlet fission ,symbols ,OLED ,Fermi's golden rule ,Molecule ,QD1-999 - Abstract
Singlet fission (SF) materials have the potential to overcome the traditional external quantum efficiency limits of organic light-emitting diodes (OLEDs). In this study, we theoretically designed an intramolecular SF molecule, 5, 5′-bitetracene (55BT), in which two tetracene units were directly connected through a C–C bond. Using quantum chemical calculation and the Fermi golden rule, we show that 55BT undergoes efficient SF induced by geometry relaxation in a locally excited singlet state, ¹(S0S1). Compared with another high-performing SF system, the tetracene dimer in the crystalline state, 55BT has advantages when used in doped systems owing to covalent bonding of the two tetracene units. This feature makes 55BT a promising candidate triplet sensitizer for near-infrared OLEDs.
- Published
- 2021
17. Effective Negative Diffusion of Singlet Excitons in Organic Semiconductors
- Author
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Alexei Halpin, Jaime Gómez Rivas, Alberto G. Curto, Anton Matthijs Berghuis, Shaojun Wang, T. V. Raziman, Surface Photonics, Photonics and Semiconductor Nanophysics, Nano-Optics of 2D Semiconductors, Center for Terahertz Science and Technology Eindhoven, and ICMS Core
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Physics ,Letter ,Anomalous diffusion ,Exciton ,02 engineering and technology ,Nanosecond ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,Photoexcitation ,Organic semiconductor ,chemistry.chemical_compound ,Condensed Matter::Materials Science ,Tetracene ,chemistry ,General Materials Science ,Singlet state ,Physical and Theoretical Chemistry ,Diffusion (business) ,0210 nano-technology - Abstract
Using diffraction-limited ultrafast imaging techniques, we investigate the propagation of singlet and triplet excitons in single-crystal tetracene. Instead of an expected broadening, the distribution of singlet excitons narrows on a nanosecond time scale after photoexcitation. This narrowing results in an effective negative diffusion in which singlet excitons migrate toward the high-density region, eventually leading to a singlet exciton distribution that is smaller than the laser excitation spot. Modeling the excited-state dynamics demonstrates that the origin of the anomalous diffusion is rooted in nonlinear triplet–triplet annihilation (TTA). We anticipate that this is a general phenomenon that can be used to study exciton diffusion and nonlinear TTA rates in semiconductors relevant for organic optoelectronics.
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- 2021
18. Singlet Fission Dynamics in the 5,12-Bis(phenylethynyl)tetracene Thin Film
- Author
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Biswajit Manna, Amitabha Nandi, and Rajib Ghosh
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Materials science ,Organic solar cell ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Tetracene ,chemistry ,Chemical physics ,Scientific method ,Singlet fission ,Physical and Theoretical Chemistry ,Thin film ,0210 nano-technology - Abstract
The singlet fission (SF) process is a promising route to overcome the Shockley and Quiesser efficiency limit of organic solar cells and hence has attracted significant research interest in the rece...
- Published
- 2021
19. Device-Based Probe of Triplet Exciton Diffusion in Singlet Fission Materials
- Author
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Russell J. Holmes, Deepesh Rai, and Tao Zhang
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Photocurrent ,Materials science ,010405 organic chemistry ,Fission ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Acceptor ,Dissociation (chemistry) ,0104 chemical sciences ,Pentacene ,Organic semiconductor ,chemistry.chemical_compound ,Tetracene ,chemistry ,Singlet fission ,General Materials Science ,Physical and Theoretical Chemistry - Abstract
Probing triplet transport in singlet fission materials can be challenging due to the presence of multiple diffusing species. We present a device-based method to measure the intrinsic triplet diffusion length (LD) in organic semiconductor thin films exhibiting singlet fission. Triplet states are optically injected into the singlet fission material of interest via energy transfer from an adjacent thin film characterized by strong spin-orbit coupling. Injected triplets migrate through the full thickness of the material before undergoing dissociation at a donor-acceptor interface. By modeling the ratio of injector and acceptor photocurrent as a function of layer thickness, the triplet LD is extracted separate from processes of unknown efficiency including singlet fission and diffusion. In considering three archetypical fission systems, a wide range is found for the triplet LD, ranging from 3.3 ± 0.4 nm for 5,12-bis((triisopropylsilyl)ethynyl)tetracene to 17.1 ± 1.3 nm for pentacene and 32.1 ± 2.6 nm for tetracene.
- Published
- 2021
20. Femtosecond stimulated Raman spectroscopy – guided library mining leads to efficient singlet fission in rubrene derivatives
- Author
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Christopher J. Douglas, Kajari Bera, and Renee R. Frontiera
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Materials science ,General Chemistry ,Chromophore ,Chemistry ,chemistry.chemical_compound ,Tetracene ,chemistry ,Chemical physics ,Singlet fission ,Femtosecond ,Physics::Atomic and Molecular Clusters ,Molecule ,Singlet state ,Spectroscopy ,Rubrene - Abstract
Chromophores undergoing singlet fission are promising candidates for harnessing solar energy as they can generate a pair of charge carriers by the absorption of one photon. However, photovoltaic devices employing singlet fission are still lacking practical applications due to the limitations within the existing molecules undergoing singlet fission. Chemical modifications to acenes can lead to efficient singlet fission devices, but the influence of changes to molecular structure on the rate of singlet fission is challenging to model and predict. Using femtosecond stimulated Raman spectroscopy we have previously demonstrated that the triplet separation process during singlet fission in crystalline rubrene is associated with the loss of electron density from its tetracene core. Based on this knowledge, we mined a library of new rubrene derivatives with electron withdrawing substituents that prime the molecules for efficient singlet fission, without impacting their crystal packing. Our rationally chosen crystalline chromophores exhibit significantly improved singlet fission rates. This study demonstrates the utility and strength of a structurally sensitive spectroscopic technique in providing insights to spectroscopy-guided materials selection and design guidelines that go beyond energy arguments to design new singlet fission-capable chromophores., In the race to find efficient singlet fission materials, picking a winner is not easy. Femtosecond stimulated Raman spectroscopy can help us choose the best candidates, as demonstrated here in choosing from a library of rubrene derivatives.
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- 2021
21. Asymmetric N-heteroacene tetracene analogues as potential n-type semiconductors
- Author
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Andrew J. P. White, Mark Oxborrow, Max Attwood, Anthony Maho, Wern Ng, Sandrine Heutz, Joseph H. L. Hadden, Hao Wu, Hiroki Akutsu, Dong Kuk Kim, Engineering & Physical Science Research Council (EPSRC), and Engineering & Physical Science Research Council (E
- Subjects
Technology ,Materials science ,Materials Science ,Heteroatom ,Materials Science, Multidisciplinary ,Crystal structure ,Physics, Applied ,ACENES ,chemistry.chemical_compound ,Materials Chemistry ,Molecule ,Thin film ,0912 Materials Engineering ,HOMO/LUMO ,0306 Physical Chemistry (incl. Structural) ,PENTACENE ,Science & Technology ,CRYSTAL ,DERIVATIVES ,Physics ,SUBSTITUTION ,0303 Macromolecular and Materials Chemistry ,General Chemistry ,STATE ,Organic semiconductor ,Crystallography ,Tetracene ,chemistry ,Physical Sciences ,THIN-FILM TRANSISTORS ,Single crystal - Abstract
In the search for high performance n-type organic semiconductors (OSCs) a simple strategy might be substitution of aromatic CH groups for nitrogen heteroatoms. Here, we report the synthesis and characterisation of two novel N-heteroacene compounds, namely, 1,5,12-triazatetracene (TrAT1) and 2,5,12-triazatetracene (TrAT2). Their potential as n-type materials is evaluated against 5,12-diazatetracene (DAT) by UV/vis and EPR spectroscopy, cyclic voltammetry, DFT, single crystal X-ray diffraction and thin film characterisation. Increasing the number of N-heteroatoms was found to stabilise the HOMO and LUMO leading to electron affinities for TrAT1 and TrAT2 of ca. −4 eV. Both compounds were found to exhibit columns of co-facial π-stacked molecules. For TrAT1, molecules are also linked by hydrogen bonding, while the crystal structure of TrAT2 was found to be inherently disordered. Thin films of DAT, TrAT1 and TrAT2 were grown by organic molecular beam deposition (OMBD) and found to form discontinuous films, where TrAT1 exhibited a preferential orientation.
- Published
- 2021
22. Triplet energy migration pathways from PbS quantum dots to surface-anchored polyacenes controlled by charge transfer
- Author
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Jianbing Zhang, Zongwei Chen, Guohui Zhao, Kao Xiong, Kaifeng Wu, and Guijie Liang
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Materials science ,Photon upconversion ,Pentacene ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Electron transfer ,Tetracene ,chemistry ,Chemical physics ,Quantum dot ,Excited state ,Ultrafast laser spectroscopy ,General Materials Science ,Spectroscopy - Abstract
Sensitization of molecular triplets using PbS quantum dots (QDs), followed by efficient triplet fusion, has been developed as a novel route to near-infrared-to-visible photon upconversion. Fundamentally, however, the mechanisms of triplet energy transfer (TET) from PbS QDs to surface-anchored polyacence acceptors remain highly debated. Here we study and side-by-side compare the kinetic pathways of TET from photoexcited PbS QDs to surface-anchored tetracene and pentacene derivatives using broad-band transient absorption spectroscopy spanning multiple decades of timescales. We find that the TET pathways are dictated by charge-transfer energetics at the QD/molecule interface. Charge transfer from QDs to tetracene was strongly endothermic, and hence spectroscopy showed one-step transformation from QD excited states to tetracene triplets in 302 ns. In contrast, hole transfer from QDs to pentacene was thermodynamically favoured and was confirmed by the formation of pentacene cation radicals in 13 ps, which subsequently evolved into pentacene triplets through a 101 ns electron transfer process. These results not only are consistent with a recently-established framework of charge-transfer-mediated TET, but also provide a route to manipulate triplet sensitization using lead-salt QDs for efficient upconversion of near-infrared photons.
- Published
- 2021
23. Rubrene untwisted: common density functional theory calculations overestimate its deviant tendencies
- Author
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Chandler Greenwell and Gregory J. O. Beran
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Electron mobility ,Materials science ,General Chemistry ,Crystal engineering ,Crystal ,Delocalized electron ,chemistry.chemical_compound ,Tetracene ,chemistry ,Chemical physics ,Materials Chemistry ,Density functional theory ,Wave function ,Rubrene - Abstract
The exceptionally high carrier mobility of rubrene derives from the combination of its intrinsic electronic properties and favorable crystal packing that facilitates charge transport. Unlike the planar conformations adopted by rubrene single crystals, however, many rubrene derivatives crystallize with a twisted tetracene core and exhibit poor carrier mobility. Typical density functional theory (DFT) calculations suggest that the twisted conformation is preferred by ∼10–14 kJ mol−1 or more in the gas phase. However, the present work shows that those calculations overestimate the twisting energy by several kJ mol−1 due to density-driven delocalization error, and that the twisting energies are actually only ∼8–10 kJ mol−1 for typical rubrene derivatives when computed with higher-level correlated wave function models. This result has two significant implications for crystal engineering with rubrene derivatives: first, DFT calculations can erroneously predict polymorphs containing twisted rubrene conformations to be more stable, when in fact structures with planar conformations are preferred, as is demonstrated here for perfluororubrene. Second, the smaller twisting energies make it more likely that solid form screening could discover new planar-core polymorphs of rubrene derivatives that have previously been crystallized only in a twisted conformation. These in turn might exhibit better organic semiconducting properties.
- Published
- 2021
24. Oriented attachment and activated dipoles leading to anisotropic H-bond-free self-assembly of n-acene derivatives into organic nanoribbons emitting linearly polarised blue light
- Author
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André Del Guerzo, Leire Gartzia-Rivero, Stéphane Massip, Christian Schäfer, Guillaume Raffy, Min-Tzu Kao, Christiaan de Vet, and Philip Schäfer
- Subjects
Ostwald ripening ,Materials science ,Intermolecular force ,General Chemistry ,Dipole ,symbols.namesake ,chemistry.chemical_compound ,Tetracene ,chemistry ,Chemical physics ,Materials Chemistry ,symbols ,Self-assembly ,Spectroscopy ,Anisotropy ,Acene - Abstract
The design of organic self-assembled nanomaterials requires a more complete understanding of all mechanisms leading to anisotropic and low-defect growth in solvent-processing, in particular in the vast case of polyaromatic compounds. 2,3-Dihexadecyloxy-9,10-diphenylanthracene (DPA16) self-assembles from solution into fluorescent nanoribbons without the addition of surfactants or polymers. These very high aspect-ratio anisotropic objects display a deep-blue emission with a remarkable linear polarisation P reaching a value of 0.6. The emission colour of ribbons can be further tuned by doping with a tetracene analogue. Crystallography, spectroscopy, atomic force and fluorescence polarisation microscopy techniques reveal that the growth mechanism not only involves a common ‘Ostwald ripening’, but also two commonly unforeseen features. First, an ‘oriented attachment’ mechanism contributes to the growth of the ribbons preventing packing mismatches. This mechanism has so far solely been demonstrated for inorganic nanoparticles. Second, a thermally activated dipole in less stable asymmetric conformations of DPA16 is proposed to contribute majorly to directional intermolecular interactions determining the main growth axis of the ribbons. These dipole–dipole interactions would contribute to explain the very high anisotropy of growth, in the absence of directional H-bonds predominating in many reported studies. This work provides new insights into the design of self-assembled nanoobjects with very high aspect ratios.
- Published
- 2021
25. Where is the best substitution position for amino groups on carbon dots: a computational strategy toward long-wavelength red emission
- Author
-
Yancong Feng, Yao Wang, Yixun Gao, Hao Li, Nengjie Cao, Bai Pengfei, Guofu Zhou, Quan Wang, and Xianggui Zhou
- Subjects
Anthracene ,Photoluminescence ,Materials science ,General Chemistry ,Time-dependent density functional theory ,Phenanthrene ,Photochemistry ,Fluorescence ,chemistry.chemical_compound ,Tetracene ,chemistry ,Materials Chemistry ,Nucleophilic substitution ,Pyrene - Abstract
Carbon dots (CDs) are a promising fluorescent material in biological and optoelectronic applications owing to their high biocompatibility, low cytotoxicity, and high stability. Red emissive CDs are not only widely used in biological imaging due to their strong tissue penetration, but also improve the color rendering index of white LEDs. However, the structure–property relationship of CDs is still not clear, and red-emissive CDs are difficult to be fabricated in experiments. In this study, we reveal the relationship between charge transfer and the photoluminescence of amino-functionalized CDs using DFT and TDDFT calculations. It is found that the charge transfer has a clear correlation with the hole contribution of amino groups. Based on the study on the amino-substituted position, it is concluded that nucleophilic substitution positions are highly critical for obtaining CDs with long-wavelength red emission (LWRE-CDs), which can be prejudged via the calculation of the atomic charges. Moreover, the universality of these correlations is demonstrated in different systems composed of polycyclic aromatic hydrocarbons (i.e., anthracene, pyrene, tetracene, and phenanthrene) and electron-donating groups (i.e., –NH2, –N(CH3)2, –OH, –OCH3, and –CH3). This work provides a theoretical guidance for the preparation of high-performance LWRE-CDs.
- Published
- 2021
26. N-type and p-type molecular doping on monolayer MoS2
- Author
-
Vo Van On, Viorel Chihaia, Do Ngoc Son, and Ong Kim Le
- Subjects
Materials science ,business.industry ,Band gap ,General Chemical Engineering ,Doping ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Semiconductor ,Adsorption ,Tetracene ,chemistry ,Chemical physics ,Monolayer ,Density functional theory ,0210 nano-technology ,business ,Visible spectrum - Abstract
Monolayer MoS2 has attracted much attention due to its high on/off current ratio, transparency, and suitability for optoelectronic devices. Surface doping by molecular adsorption has proven to be an effective method to facilitate the usage of MoS2. However, there are no works available to systematically clarify the effects of the adsorption of F4TCNQ, PTCDA, and tetracene on the electronic and optical properties of the material. Therefore, this work elucidated the problem by using density functional theory calculations. We found that the adsorption of F4TCNQ and PTCDA turns MoS2 into a p-type semiconductor, while the tetracene converts MoS2 into an n-type semiconductor. The occurrence of a new energy level in the conduction band for F4TCNQ and PTCDA and the valence band for tetracene reduces the bandgap of the monolayer MoS2. Besides, the MoS2/F4TCNQ and MoS2/PTCDA systems exhibit an auxiliary optical peak at the long wavelengths of 950 and 850 nm, respectively. Contrastingly, the MoS2/tetracene modifies the optical spectrum of the monolayer MoS2 only in the ultraviolet region. The findings are in good agreement with the experiments.
- Published
- 2021
27. Singlet Fission Dynamics in Tetracene Single Crystals Probed by Polarization-Dependent Two-Dimensional Electronic Spectroscopy
- Author
-
Guodong Wang, Zhixing Liu, Chunfeng Zhang, Haibo Ma, Rui Wang, Xiaoyong Wang, and Min Xiao
- Subjects
010304 chemical physics ,Chemistry ,Exciton ,010402 general chemistry ,01 natural sciences ,Electron spectroscopy ,Molecular physics ,0104 chemical sciences ,chemistry.chemical_compound ,Tetracene ,Molecular vibration ,0103 physical sciences ,Singlet fission ,Molecule ,Singlet state ,Physical and Theoretical Chemistry ,Excitation - Abstract
The exact mechanism of endothermic singlet fission in crystalline polyacene remains to be clarified. It has been elusive whether the excess energy of vibrational hot states and the upper branch of Davydov splitting is important for the energy compensation. Here, we probe the excited-state specified singlet fission dynamics in tetracene single crystals by polarization-dependent two-dimensional electronic spectroscopy (2DES). While a major spectral transfer with a characteristic lifetime of 86 ps is observed to be largely independent of the excitation energy due to formation of the spatially separated triplet pairs (1(T···T)), the excitation-energy dependent subpicosecond dynamics show marked differences for different states probed, implying the possible involvement of a coherently formed triplet pair state (1(TT)). Analysis of coherent vibrational modes suggests the coupling to high energy modes may offset the energy difference between singlet and triplet pair states. Moreover, the beating map of the low frequency mode indicates a vibrational hot state violating the aggregation behavior of Davydov exciton, which can be explained as a resonance of the 1(TT) state. These results suggest that the coherent vibronic mixing between local excitation and triplet pair states is essential for the singlet fission dynamics in molecule aggregates.
- Published
- 2020
28. Effect of Sulfur Substitution on Charge Transport Ability of Benzopyrazine-Fused Tetracene Derivatives: A Theoretical Study
- Author
-
Hyunbok Lee
- Subjects
Materials science ,Materials Science (miscellaneous) ,Substitution (logic) ,chemistry.chemical_element ,Charge (physics) ,General Medicine ,Condensed Matter Physics ,Photochemistry ,Sulfur ,Organic semiconductor ,chemistry.chemical_compound ,Tetracene ,chemistry ,Density functional theory ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry - Published
- 2020
29. Understanding Intermolecular Interactions in a Tetracene–F4TCNQ Cocrystal via Its Electron Density Distribution and Topology
- Author
-
Kamil A. Ivshin, Bernd Büchner, Martin Knupfer, Olga N. Kataeva, Marcus Nohr, and Silke Hampel
- Subjects
Materials science ,010405 organic chemistry ,Intermolecular force ,Charge (physics) ,General Chemistry ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,Cocrystal ,0104 chemical sciences ,chemistry.chemical_compound ,Electron density distribution ,Tetracene ,chemistry ,Chemical physics ,General Materials Science ,Spectroscopy ,Topology (chemistry) - Abstract
High-quality single crystals of the charge transfer compound tetracene–F4TCNQ (1:1) were grown by physical vapor transport and characterized by IR and UV/vis spectroscopy as well as by accurate sin...
- Published
- 2020
30. Synthesis and Crystal Engineering of Rubrene and Its Derivatives
- Author
-
Christopher J. Douglas, Emma C. Murphy, and Margaret L. Clapham
- Subjects
Organic electronics ,chemistry.chemical_compound ,Tetracene ,Chemistry ,Charge carrier mobility ,Organic Chemistry ,Organic crystal ,Nanotechnology ,Crystal engineering ,Rubrene ,Catalysis ,Electronic properties - Abstract
Rubrene (5,6,11,12-tetraphenyltetracene) is a polyacene material that has been well studied throughout its nearly one-hundred year history. Originally found fascinating for its luminescent properties, it has emerged at the forefront for organic electronics due to its particularly high charge carrier mobility for an organic crystal. Despite great interest and its explosion in the literature over the past two decades, the commercial synthesis of rubrene has remained relatively unchanged since its initial discovery in 1926. Several recent studies have reported alternate routes to the rubrene structure with substitutions on the peripheral aromatic rings and tetracene core. Substituting in this manner has the potential to improve upon rubrene’s electronic properties. We review the various routes to rubrene and its derivatives and provide a brief overview of the solid-state library available for study. The information gained by comparing the solid-state properties between derivatives offers insight into unpredictable crystallization and polymorphism – complicated issues – which have hindered research into materials applications of rubrene. We hope that these insights inspire work in application-driven synthetic chemistry for future rubrene derivatives.1 Introduction2 Synthesis2.1 Traditional Rubrene Synthesis2.1.1 Recent Applications2.2 Multi-Step Synthesis2.2.1 Historical Routes2.2.2 Diels–Alder Approaches2.2.3 Cross-Coupling Approaches2.2.4 Comparative Synthesis of Perfluororubrene3 Crystal Engineering4 Conclusions and Outlook
- Published
- 2020
31. Steady-State Fluorescence Signatures of Intramolecular Singlet Fission from Stochastic Predictions
- Author
-
David J. Walwark and John K. Grey
- Subjects
010304 chemical physics ,Chemistry ,Chromophore ,010402 general chemistry ,01 natural sciences ,Fluorescence ,Fluorescence spectroscopy ,0104 chemical sciences ,Pentacene ,chemistry.chemical_compound ,Tetracene ,Chemical physics ,Intramolecular force ,0103 physical sciences ,Singlet fission ,Ultrafast laser spectroscopy ,Physical and Theoretical Chemistry - Abstract
The advent of new multichromophoric systems capable of undergoing efficient intramolecular singlet fission (iSF) has greatly expanded the range of possible motifs for multiexciton generation approaches for organic light energy harvesting materials. Transient absorption (TA) spectroscopic probes are typically used to characterize singlet fission processes that may place limitations on sensitivity and time resolution on scales comparable to the full lifespan of spin-forbidden triplets and interactions. Here, we investigate the ability of fluorescence-based spectroscopic probes to detect iSF activity in isolated dyads based on large substituted conjugated acenes (e.g., tetracene and pentacene derivatives). Photophysical models are simulated from several iSF-active dyad systems reported in the literature using a stochastic approach to assess the sensitivity of steady-state fluorescence to the presence of triplet excitons. The results demonstrate large fluctuations in expected fluorescence yields with varying excitation rate constants for systems with ΦiSF > 0.5 (assuming weak interchromophore coupling). Exciton-exciton interactions are also investigated, and we further demonstrate how treating iSF dyads stochastically (i.e., finite number of chromophores) accentuates dependences of photophysical yields with excitation rates. Last, our approach reveals the potential ability of single molecule level fluorescence spectroscopy to detect iSF activity that can aid efforts to design and optimize candidate iSF systems.
- Published
- 2020
32. Synthesis, crystal structure and charge transport characteristics of stable peri-tetracene analogues†
- Author
-
Chihaya Adachi, Ryota Nakamura, and Masashi Mamada
- Subjects
Materials science ,Charge (physics) ,General Chemistry ,Crystal structure ,chemistry.chemical_compound ,Chemistry ,Tetracene ,chemistry ,Zigzag ,Computational chemistry ,Electron configuration ,Singlet state ,Acene ,Perylene - Abstract
peri-Acenes have shown great potential for use as functional materials because of their open-shell singlet biradical character. However, only a limited number of peri-acene derivatives larger than peri-tetracene have been synthesized to date, presumably owing to the low stability of the target compounds in addition to the complicated synthesis scheme. Here, a very simple synthesis route for the tetrabenzo[a,f,j,o]perylene (TBP) structure enables the development of highly stable peri-tetracene analogues. Despite a high degree of singlet biradical character, the compounds with four substituents at the zigzag edge show a remarkable stability in solution under ambient conditions, which is better than that of acene derivatives with a closed-shell electronic configuration. The crystal structures of the TBP derivatives were obtained for the first time; these are valuable to understand the relationship between the structure and biradical character of peri-acenes. The application of peri-acenes in electronic devices should also be investigated. Therefore, the semiconducting properties of the TBP derivative were investigated by fabricating the field-effect transistors., Highly stable peri-tetracene analogues with a high degree of singlet biradical character were synthesized in a very simple route, and their crystal structures and semiconducting properties were investigated.
- Published
- 2020
33. Excitation dynamics in polyacene molecules on rare-gas clusters
- Author
-
Matthias Bohlen, Rupert Michiels, Moritz Michelbach, Selmane Ferchane, Michael Walter, Alexander Eisfeld, Frank Stienkemeier, and Publica
- Subjects
Chemical Physics (physics.chem-ph) ,Argon lasers ,anthracene ,FOS: Physical sciences ,General Physics and Astronomy ,rare-gas clusters ,Argon clusters ,excitation dynamics ,solid argon ,laser excitation ,decay dynamics ,Spectra's ,Physics - Chemical Physics ,argon ,Pentacenes ,Physics::Atomic and Molecular Clusters ,excitation density ,molecules ,Physical and Theoretical Chemistry ,Physics::Chemical Physics ,cluster sizes ,Tetracene - Abstract
Laser-induced fluorescence spectra and excitation lifetimes of anthracene, tetracene, and pentacene molecules attached to the surface of solid argon clusters have been measured with respect to cluster size, density of molecules, and excitation density. Results are compared to previous studies on the same sample molecules attached to neon clusters. A contrasting lifetime behavior of anthracene on neon and argon clusters is discussed, and mechanisms are suggested to interpret the results. Although both neon and argon clusters are considered to be weakly interacting environments, we find that the excitation decay dynamics of the studied acenes depends significantly on the cluster material. Moreover, we find even qualitative differences regarding the dependence on the dopant density. Based on these observations, previous assignments of collective radiative and non-radiative decay mechanisms are discussed in the context of the new experimental findings.& nbsp;(c) 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
- Published
- 2022
34. Resistance to Unwanted Photo-Oxidation of Multi-Acene Molecules
- Author
-
Ioannis Kymissis, Samuel W. Thomas, Zachary A. Lamport, and Yu Yan
- Subjects
Anthracene ,010405 organic chemistry ,Organic Chemistry ,Arylene ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Fluorescence ,Fluorescence spectroscopy ,0104 chemical sciences ,chemistry.chemical_compound ,Tetracene ,chemistry ,Molecule ,Photosensitizer ,Acene - Abstract
Although long acenes remain a key class of π-conjugated molecules for numerous applications, photoinduced oxidation upon exposure of the acene to light, often through sensitization of 1O2, is an important reaction requiring mitigation for most applications. In response to this ongoing challenge, this paper presents a series of four new diarylethynyl-substituted long acenes-three tetracenes and one anthradithiophene-in which the arylene pendants are either benzene, naphthalene, or anthracene. UV/vis and fluorescence spectroscopy reveals that the anthracene-substituted derivatives fluoresce poorly (Φ < 0.01). Although all four long acenes react with 1O2 at expected rates when an external photosensitizer is included and show the expected changes in fluorescence to accompany these reactions, the anthracene-substituted derivatives resist direct photoinduced oxidation. Through a combination of mechanistic experiments, we conclude that rapid nonradiative decay of the anthracene-substituted derivatives, perhaps because of inter-arene torsions that emerge in theoretical geometry optimizations, makes these compounds poor photosensitizers for 1O2 or other reactive oxygen species. This discovery opens new design possibilities for extended acene structures with improved photochemical stability.
- Published
- 2020
35. Non-substituted fused bis-tetracene based thin-film transistor with self-assembled monolayer hybrid dielectrics
- Author
-
Dominik Lungerich, Marcus Halik, Konstantin Amsharov, Marco Sarcletti, Judith E. Wittmann, Mikhail Feofanov, Baolin Zhao, Tobias Rejek, and Hyoungwon Park
- Subjects
Organic electronics ,Electron mobility ,Materials science ,Organic field-effect transistor ,business.industry ,Self-assembled monolayer ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Tetracene ,Semiconductor ,chemistry ,Thin-film transistor ,Monolayer ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
Polycyclic aromatic hydrocarbons with zigzag peripheries are high perspective candidates for organic electronics. However, large fused acenes are still poorly studied due to the tedious synthesis. Herein we report a non-substituted fused bistetracene DBATT (2.3,8.9-dibenzanthanthrene) as the semiconductor on low-voltage-driven organic thin-film transistors. The systematic studies of thin-film growth on various self-assembled monolayer (SAM) modified gate dielectrics and the electrical performances were carried out. The sub-monolayer of the semiconductor film shows larger island domains on the alkyl chain SAM. This device exhibits the hole mobility of 0.011 cm2·V−1·s−1 with a current ratio of IonIIoff above 105.
- Published
- 2020
36. Role of Intermolecular Interactions in the Excited-State Photophysics of Tetracene and 2,2′-Ditetracene
- Author
-
Anke Krueger, U. Müller, Sebastian Hammer, Maximilian Frank, Lena Roos, Marian Deutsch, Bernd Engels, Marcel Krumrein, Todd B. Marder, Alexandra Friedrich, and Jens Pflaum
- Subjects
Materials science ,Intermolecular force ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Tetracene ,chemistry ,Excited state ,Singlet fission ,Physical and Theoretical Chemistry ,0210 nano-technology ,Derivative (chemistry) - Abstract
We carried out a comparative study on the excited-state properties of tetracene, which is prone to singlet fission, and its 2,2′-ditetracene derivative to analyze the dependence of such loss channe...
- Published
- 2020
37. Thiol-Anchored TIPS-Tetracene Ligands with Quantitative Triplet Energy Transfer to PbS Quantum Dots and Improved Thermal Stability
- Author
-
Victor Gray, Akshay Rao, Zhilong Zhang, Antonios M. Alvertis, Jesse R. Allardice, John E. Anthony, Neil C. Greenham, Simon Dowland, James Xiao, Gray, Victor [0000-0001-6583-8654], Zhang, Zhilong [0000-0001-9903-4945], Allardice, Jesse R [0000-0002-1969-7536], Alvertis, Antonios M [0000-0001-5916-3419], Greenham, Neil C [0000-0002-2155-2432], Anthony, John E [0000-0002-8972-1888], Rao, Akshay [0000-0003-4261-0766], Apollo - University of Cambridge Repository, and Apollo-University Of Cambridge Repository
- Subjects
Imagination ,Chemical substance ,Materials science ,media_common.quotation_subject ,Physics::Optics ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,01 natural sciences ,7. Clean energy ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,General Materials Science ,Thermal stability ,Physical and Theoretical Chemistry ,media_common ,chemistry.chemical_classification ,Nanocomposite ,34 Chemical Sciences ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Tetracene ,chemistry ,Quantum dot ,Thiol ,0210 nano-technology ,Science, technology and society - Abstract
Triplet energy transfer between inorganic quantum dots (QDs) and organic materials plays a fundamental role in many optoelectronic applications based on these nanocomposites. Attaching organic molecules to the QD as transmitter ligands has been shown to facilitate transfer both to and from QDs. Here we show that the often disregarded thiol anchoring group can achieve quantitative triplet energy transfer yields in a PbS QD system with 6,11-bis[(triisopropylsilyl)ethynyl]tetracene-2-methylthiol (TET-SH) ligands. We demonstrate efficient triplet transfer in a singlet fission-based photon multiplication system with 5,12-bis[(triisopropylsilyl)ethynyl]tetracene generating triplets in solution that transfer to the PbS QDs via the thiol ligand TET-SH. Importantly, we demonstrate the increased thermal stability of the PbS/TET-SH system, compared to the traditional carboxylic acid counterpart, allowing for higher photoluminescence quantum yields.
- Published
- 2020
38. Synthesis, Hirshfeld Surface Analysis and DFT Studies of Ethano-tetracyclic Tetracene Derivatives
- Author
-
Mujeeb A. Sultan, Mansour S. A. Galil, Saied M. Soliman, Hazem A. Ghabbour, and Renjith Raveendran Pillai
- Subjects
Intermolecular force ,Crystal system ,Regioselectivity ,General Chemistry ,Crystal structure ,Alkaline hydrolysis (body disposal) ,010402 general chemistry ,010403 inorganic & nuclear chemistry ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,Tetracene ,chemistry ,Orthorhombic crystal system ,Organometallic chemistry - Abstract
The syntheses of ethano-tetracyclic tetracenes; 14-cyano-5,12-dihydro-5,12-ethanotetracen-14-yl acetate (2a and 2b) and 5,12-dihydro-5,12-ethanotetracen-13-one (3) are reported. The tetracenes isomers 2a and 2b are equally obtained via DA reaction and the tetracene 3 is synthesized from the alkaline hydrolysis of 2a and 2b. The DFT calculations of tetracenes isomers 2a and 2b are performed and gave good agreement to the experimental result. The structure of tetracene 3 is elucidated by X-ray technique and its intermolecular interactions are determined by Hirshfeld surface analysis. The crystal system of tetracene 3 is orthorhombic with a Pca21 space group; a = 28.589 (5) A, b = 6.5023 (14) A, c = 7.5101 (11) A, V = 1396.1 (4) A3, Z = 4. This is the first report describing syntheses Ethano-tetracyclic tetracenes 2a, 2b, 3. DFT studies were used to explain the reaction regioselectivity of the two tetracene isomers 2a, 2b. The x-ray is performed to elucidate the structure of tetracene 3. Hirshfeld surface analysis is performed to determine the intermolecular interactions in the crystal structure of the tetracene 3.
- Published
- 2020
39. Copper-Catalyzed N,N-Diarylation of Amides for the Construction of 9,10-Dihydroacridine Structure and Applications in the Synthesis of Diverse Nitrogen-Embedded Polyacenes
- Author
-
Mei-Xiang Wang, Sheng-Kai Hou, Shuo Tong, Jingsong You, and Mei-Ling Tan
- Subjects
Organic Chemistry ,Aromatization ,chemistry.chemical_element ,Biochemistry ,Combinatorial chemistry ,Nitrogen ,Fluorescence ,Catalysis ,chemistry.chemical_compound ,Tetracene ,chemistry ,Acridine ,Copper catalyzed ,Physical and Theoretical Chemistry ,Luminescence - Abstract
We reported herein CuI/DMEDA catalyzed N,N-diarylation reaction of amides with various di(o-bromoaryl)methanes to produce diverse 9,10-dihydroacridine derivatives. The resulting 9,10-dihydroacridine derivatives were oxidized selectively under mild conditions to afford acridine, acridinone, and acridinium derivatives. The copper-catalyzed N,N-diarylation reaction coupled with oxidative aromatization reaction enabled the facile construction of nitrogen atom-embedded tetracenes and pentacenes of different ortho-fused patterns. The luminescence properties, especially the effect of fusion pattern on fluorescence emission of acquired N-polycenes, were also demonstrated.
- Published
- 2020
40. Light-Matter Coupling Strength Controlled by the Orientation of Organic Crystals in Plasmonic Cavities
- Author
-
Mohammad Ramezani, Anton Matthijs Berghuis, Jaime Gómez Rivas, Vincent Serpenti, Shaojun Wang, Surface Photonics, Photonics and Semiconductor Nanophysics, and ICMS Core
- Subjects
Coupling ,Condensed Matter::Quantum Gases ,Plasmonic nanoparticles ,Materials science ,Condensed matter physics ,Condensed Matter::Other ,Exciton ,Physics::Optics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Dipole ,General Energy ,Tetracene ,chemistry ,Polariton ,Physical and Theoretical Chemistry ,0210 nano-technology ,Anisotropy ,Plasmon - Abstract
Strong light–matter coupling is a powerful mechanism to engineer materials properties and a platform to study polariton physics. Excitons in organic crystals are interesting candidates for the investigation of light–matter coupling due to the large magnitude and well-defined orientation of their transition dipole moments. We demonstrate the coupling of excitons in tetracene crystals to optical modes in open cavities formed by anisotropic arrays of plasmonic nanoparticles and investigate the coupling strength as a function of the alignment of the exciton dipole moment to the cavity field. The anisotropy of the cavity and the crystal provides a practical method to tune the light–matter coupling strength from weak to the onset of the strong coupling regime, by rotating the crystal with respect to the plasmonic array. The possibility to control the coupling within a single excitonic material, paves the way to study the effects of the coupling strength on polariton physics, such as exciton-polariton dynamics, transport, or condensation.
- Published
- 2020
41. Fluorescence Anisotropy Decay of Molecular Rotors with Acene Rotators in Viscous Solution
- Author
-
Ronnie V. Garcia, Miguel A. Garcia-Garibay, Nicole A. Barbour, and Morgan E. Howe
- Subjects
chemistry.chemical_compound ,Viscosity ,Anthracene ,Tetracene ,chemistry ,Organic Chemistry ,Molecular rotors ,Rotation ,Molecular physics ,Acene ,Article ,Fluorescence anisotropy ,Naphthalene - Abstract
Herein we report the use of fluorescence anisotropy decay for measuring the rotation of six shape-persistent molecular rotors with central naphthalene (2), anthracene (3a, 3b and 3c), tetracene (4), and pentacene (5) rotators axially linked by triple bonds to bulky trialkylsilyl groups of different size. Steady-state and time-resolved polarization measurements carried out in mineral oil confirmed that the vibrationally-resolved lowest energy absorption bands are characterized by a transition dipole moment oriented along the short acene axes, in the direction of the alkyne linkers. Fluorescence lifetimes increased significantly with increasing acene size and moderately with a decrease in the size of the trialkylsilyl group. The fluorescence anisotropy decay for all compounds in mineral oil with a viscosity of ca. 21.6 cP at 40 °C was completed within the fluorescence lifetime, so that the rotational time constants could be obtained via their rotational correlation times, which increased with silyl protecting group size rather than acene size, indicating that polarization decay is determined by tumbling of the molecular rotor about the long acene axis. These results suggest that monitoring the rotational motion of bis(silylethynyl)acenes in restricted media should be possible for media with viscosity values on the order of 21.6 cP or greater.
- Published
- 2020
42. Ab Initio Linear and Pump–Probe Spectroscopy of Excitons in Molecular Crystals
- Author
-
Timothy C. Berkelbach and A. Lewis
- Subjects
Materials science ,Absorption spectroscopy ,Ab initio ,Molecular physics ,chemistry.chemical_compound ,Tetracene ,chemistry ,Ab initio quantum chemistry methods ,Excited state ,Singlet fission ,General Materials Science ,Physical and Theoretical Chemistry ,Spectroscopy ,Acene - Abstract
Linear and nonlinear spectroscopies are powerful tools used to investigate the energetics and dynamics of electronic excited states of both molecules and crystals. While highly accurate ab initio calculations of molecular spectra can be performed relatively routinely, extending these calculations to periodic systems is challenging. Here, we present calculations of the linear absorption spectrum and pump-probe two-photon photoemission spectra of the naphthalene crystal using equation-of-motion coupled-cluster theory with single and double excitations (EOM-CCSD). Molecular acene crystals are of interest due to the low-energy multiexciton singlet states they exhibit, which have been studied extensively as intermediates involved in singlet fission. Our linear absorption spectrum is in good agreement with experiment, predicting a first exciton absorption peak at 4.4 eV, and our two-photon photoemission spectra capture the qualitative behavior of multiexciton states, whose double-excitation character cannot be captured by current methods. The simulated pump-probe spectra provide support for existing interpretations of two-photon photoemission experiments in closely related acene crystals such as tetracene and pentacene.
- Published
- 2020
43. Molecular modelling and simulation for the design of molecular diodes using density functional theory
- Author
-
Shamoon Ahmad Siddiqui
- Subjects
chemistry.chemical_classification ,Materials science ,010304 chemical physics ,General Chemical Engineering ,Electron donor ,02 engineering and technology ,General Chemistry ,Electron acceptor ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Photochemistry ,01 natural sciences ,Acceptor ,chemistry.chemical_compound ,Tetracene ,chemistry ,Modeling and Simulation ,0103 physical sciences ,Molecule ,General Materials Science ,Density functional theory ,0210 nano-technology ,Information Systems ,Diode - Abstract
Three molecular species were modelled using TCNQ molecule as the electron acceptor and DBTTF, Tetracene and ADT molecules as the electron donor. These donor and acceptor moieties were separated by an insulating σ bridge to design suitable molecular diodes. All the molecular geometries were optimised by using the density functional theory based methods. To investigate the performance of these molecular species for the design of molecular diodes, ranging electric field was applied in two directions that are from donor to acceptor moieties and from acceptor to donor moieties. The effect of the electric field in both directions was thoroughly observed on the HOMO energy, LUMO energy, HOMO–LUMO energy gap, the spatial distribution of both frontier molecular orbitals and on the induced electric dipole moment. The outcome of the present investigation strongly suggests that charge transport is highly probable in one direction only, which means that these molecular species may be the excellent contenders for the design of molecular diodes.
- Published
- 2020
44. A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase
- Author
-
Mikhail M. Evseev, Eugene K. Bashkirov, Bo Xu, Utuq Ablikim, Musahid Ahmed, Ralf I. Kaiser, Alexander M. Mebel, Long Zhao, and Valeriy N. Azyazov
- Subjects
Reaction mechanism ,Annulation ,010405 organic chemistry ,Chemistry ,General Chemistry ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,Phenacene ,Catalysis ,0104 chemical sciences ,Molecular wire ,chemistry.chemical_compound ,Tetracene ,Helicene ,Computational chemistry ,Vinylacetylene - Abstract
A unified low-temperature reaction mechanism on the formation of acenes, phenacenes, and helicenes-polycyclic aromatic hydrocarbons (PAHs) that are distinct via the linear, zigzag, and ortho-condensed arrangements of fused benzene rings-is revealed. This mechanism is mediated through a barrierless, vinylacetylene mediated gas-phase chemistry utilizing tetracene, [4]phenacene, and [4]helicene as benchmarks contesting established ideas that molecular mass growth processes to PAHs transpire at elevated temperatures. This mechanism opens up an isomer-selective route to aromatic structures involving submerged reaction barriers, resonantly stabilized free-radical intermediates, and systematic ring annulation potentially yielding molecular wires along with racemic mixtures of helicenes in deep space. Connecting helicene templates to the Origins of Life ultimately changes our hypothesis on interstellar carbon chemistry.
- Published
- 2020
45. Molecular insights and concepts to engineer singlet fission energy conversion devices
- Author
-
Dominik Thiel, Andreas Kunzmann, Rubén Casillas, Ilias Papadopoulos, Dirk M. Guldi, and Tobias Ullrich
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Intermolecular force ,Nanotechnology ,Energy conversion devices ,Pollution ,Pentacene ,chemistry.chemical_compound ,Tetracene ,Nuclear Energy and Engineering ,chemistry ,Intramolecular force ,Singlet fission ,Solar energy conversion ,Environmental Chemistry ,Energy transformation - Abstract
In this Review, we showcase the fundamental processes of intermolecular and intramolecular singlet fission (SF). Furthermore we prioritize the information, which is relevant for the implementation of SF and SF-materials into solar energy conversion devices. We do this, firstly, by referring to the complexity of SF, and discussing key aspects of it; secondly, by mentioning the instrumental efforts, which assisted in unraveling SF in benchmark molecular building blocks such as tetracene, pentacene, and their corresponding dimers/oligomers; thirdly, by presenting a collection of SF-materials, as well as available photophysical and electrochemical data for energy conversion research. Among others, these include perylene-diimides (PDIs), diketopyrrolopyrroles (DPPs), carotenoids, conjugated polymers, and diradicaloids. This Review is rounded off by discussing pioneering contributions of SF in solar energy conversion schemes and highlighting recent developments in the field. Overall, a set of guidelines is given for new directions in SF, that is, the use of new tools to discover new SF-materials (i.e. spectroscopy, computation, machine-learning) and deposition processes (i.e. thin-films, DSSCs, OPVs) to couple SF-materials with the appropriate semiconductors.
- Published
- 2020
46. Tuning singlet fission in amphipathic tetracene nanoparticles by controlling the molecular packing with side-group engineering
- Author
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Heyuan Liu, Sainan Zhou, Shanshan Liu, Zhaofeng Tang, Xiyou Li, Li Shen, Xiangyang Wang, and Xiaoqing Lu
- Subjects
Materials science ,Nanoparticle ,Photochemistry ,Dissociation (chemistry) ,chemistry.chemical_compound ,Tetracene ,chemistry ,Singlet fission ,Ultrafast laser spectroscopy ,Materials Chemistry ,Molecule ,General Materials Science ,Triplet state ,Ground state - Abstract
Three tetracene derivatives with one (DPhTc-COOH), two (DPhTc-(COOH)2) or no (DPhTc) carboxylic groups are synthesized and prepared into colloidal nanoparticles in aqueous solution. Theoretical simulation shows that various molecular arrangements are adopted in these three nanoparticles. So different electronic coupling strengths between tetracene units are achieved in these three nanoparticles. Transient absorption spectra demonstrate that SF can occur in all nanoparticles but with different SF dynamics and efficiencies depending on the coupling strength among the adjacent tetracene units. In DPhTc-COOH NPs with strong interactions, efficient SF can proceed quickly, but the resulting triplet pair cannot dissociate into free triplets and recombines into the ground state quickly. When the interaction decreases in DPhTc-(COOH)2 and DPhTc NPs, SF will become slow and less efficient but the triplet pair can dissociate into free triplets or partially separated triplets. Our results demonstrate successfully that the number of carboxylic groups influences the tetracene packing and coupling in nanoparticles, as well as the SF kinetics and efficiency. Strong interactions between tetracene units are necessary for quick and efficient SF, but the formed triplet pair cannot separate into a long-lived triplet state. To get a high free triplet yield, elaborate tuning of the interaction among the tetracene molecules to achieve quick dissociation of the triplet pair is necessary.
- Published
- 2020
47. A systematic analysis of excitonic properties to seek optimal singlet fission: the BN-substitution patterns in tetracene
- Author
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Hans Lischka, Adelia J. A. Aquino, Francisco B. C. Machado, Max Pinheiro, and Felix Plasser
- Subjects
Materials science ,Exciton ,General Chemistry ,Electronic structure ,Photoexcitation ,chemistry.chemical_compound ,Tetracene ,chemistry ,Chemical physics ,Excited state ,Singlet fission ,Materials Chemistry ,Molecule ,Singlet state - Abstract
The development of efficient organic-based photovoltaic devices is a vibrant area of research with the potential of providing a cheap source of sustainable energy to society. The attainable power conversion efficiencies could be strongly enhanced via the singlet fission (SF) mechanism, a quantum mechanical phenomenon that potentially doubles the number of electron–hole pairs in a photoexcitation process by splitting a high energy singlet into two triplets. Biradicaloid molecules are particularly appealing for SF applications due to the possibility of controlling the balance between open-shell and closed-shell resonance structures via chemical modifications, which open new opportunities to fine tune the singlet and triplet excitation energies, and thus maximize the SF efficiency. Recently, we have shown that doping acenes with boron (B) or nitrogen (N) atoms leads to a large modulation in its biradicaloid nature at the ground-state. Herein, this previous study is extended to the case of asymmetric substitutions by introducing a BN-pair in a tetracene molecule to form azaborine analogues of acenes. The consequences of the chemical doping on the excitonic properties of tetracene are investigated through high-level multireference calculations. From a pool of 60 proposed BN-tetracene chromophores, we identify 15 new promising candidates for SF as they satisfy the energy level matching conditions involving the low-lying singlet and triplet states of a monomer. Still, some of these compounds show good chemical stability as evidenced by their modest biradical character. These results are interpreted in terms of aromaticity changes, charge transfer effects and exciton properties. More generally, this study shows how the energetics of singlet fission materials can be dramatically altered by using fairly simple chemical substitutions and provides detailed insight into the underlying relationships between the molecular structure, the electronic structure, and the excited state energies.
- Published
- 2020
48. Identifying high-mobility tetracene derivatives using a non-adiabatic molecular dynamics approach
- Author
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Orestis George Ziogos, Matthew Ellis, Samuele Giannini, and Jochen Blumberger
- Subjects
Organic electronics ,Materials science ,Stacking ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Polaron ,7. Clean energy ,01 natural sciences ,0104 chemical sciences ,Molecular wire ,chemistry.chemical_compound ,Molecular dynamics ,Delocalized electron ,Tetracene ,chemistry ,Chemical physics ,Materials Chemistry ,Soft matter ,0210 nano-technology - Abstract
The search for conductive soft matter materials with significant charge mobility under ambient conditions has been a major priority in organic electronics (OE) research. Alkylated tetracenes are promising cost-effective candidate molecules that can be synthesized using wet chemistry methods, resulting in columnar single crystals with pronounced structural stability at and above room temperature. A remarkable characteristic of these materials is the capability of tuning the tetracene core intracolumnar stacking pattern and the crystal melting point via the side chain length and type modifications. In this study, we examine the performance of a series of alkylated tetracenes as hole conducting materials using a novel atomistic simulation technique that allows us to predict both the charge transport mechanism and mobilities. Our simulations demonstrate that molecular wires of alkylated tetracenes are capable of polaronic hole conduction at room temperature, with mobility values ranging up to 21 cm2 V−1 s−1, thus rendering such materials a highly promising choice for flexible OE applications. As regards the charge transfer robustness, two promising tetracene derivatives are identified with the capability of seamless inter-wire polaron delocalization, alleviating possible transfer bottlenecks due to local molecular defects. Our findings suggest that alkylated tetracenes offer an attractive route towards flexible columnar OE materials with unprecedented hole mobilities.
- Published
- 2020
49. Optimal Arrangements of Tetracene Molecule Pairs for Fast Singlet Fission
- Author
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Zdeněk Havlas, Josef Michl, and Eric A. Buchanan
- Subjects
chemistry.chemical_compound ,Tetracene ,010405 organic chemistry ,Chemistry ,Singlet fission ,Molecule ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Molecular physics ,0104 chemical sciences - Abstract
In search for a qualitative understanding of the effects of molecular packing on singlet fission (SF) rate, a simplified version of the frontier orbital model is described and illustrated on a pair...
- Published
- 2019
50. Singlet fission in a hexacene dimer: energetics dictate dynamics†
- Author
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Kealan J. Fallon, Elango Kumarasamy, Luis M. Campos, Matthew Y. Sfeir, and Samuel N. Sanders
- Subjects
Materials science ,Dimer ,Exciton ,General Chemistry ,Chromophore ,Molecular physics ,Hexacene ,chemistry.chemical_compound ,Chemistry ,Tetracene ,chemistry ,Singlet fission ,Physics::Atomic and Molecular Clusters ,Condensed Matter::Strongly Correlated Electrons ,Singlet state ,Ground state - Abstract
Singlet fission (SF) is an exciton multiplication process with the potential to raise the efficiency limit of single junction solar cells from 33% to up to 45%. Most chromophores generally undergo SF as solid-state crystals. However, when such molecules are covalently coupled, the dimers can be used as model systems to study fundamental photophysical dynamics where a singlet exciton splits into two triplet excitons within individual molecules. Here we report the synthesis and photophysical characterization of singlet fission of a hexacene dimer. Comparing the hexacene dimer to analogous tetracene and pentacene dimers reveals that excess exoergicity slows down singlet fission, similar to what is observed in molecular crystals. Conversely, the lower triplet energy of hexacene results in an increase in the rate of triplet pair recombination, following the energy gap law for radiationless transitions. These results point to design rules for singlet fission chromophores: the energy gap between singlet and triplet pair should be minimal, and the gap between triplet pair and ground state should be large., We report the synthesis and photophysical characterization of highly exoergic singlet fission in a hexacene dimer revealing exciton dynamics that follow the energy gap law.
- Published
- 2019
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