scholarly journals Singlet fission in thin films of metallo-supramolecular polymers with ditopic thiophene-bridged terpyridine ligands

2017 ◽  
Vol 5 (32) ◽  
pp. 8041-8051 ◽  
Author(s):  
David Rais ◽  
Jiří Pfleger ◽  
Miroslav Menšík ◽  
Alexander Zhigunov ◽  
Pavla Štenclová ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Supramolecular Polymers ◽  
Uv Laser ◽  
Singlet Fission ◽  
Thin Solid Films ◽  
Singlet Exciton ◽  
Solid Films ◽  
Terpyridine Ligands ◽  
Singlet Exciton Fission

Ultrafast singlet exciton fission in thin solid films after UV laser photoexcitation was observed using transient absorption spectroscopy.

scholarly journals Ultrafast spectroscopy reveals singlet fission, ionization and excimer formation in perylene film

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenjun Ni ◽  
Licheng Sun ◽  
Gagik G. Gurzadyan
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Photovoltaic Devices ◽  
Singlet Fission ◽  
Time Resolved ◽  
Singlet Exciton ◽  
Femtosecond Transient Absorption ◽  
Photovoltaic Applications ◽  
Singlet Exciton Fission ◽  
Triplet Formation

AbstractSinglet exciton fission (SF) is a spin-allowed process whereby two triplet excitons are created from one singlet exciton. This phenomenon can offset UV photon energy losses and enhance the overall efficiency in photovoltaic devices. For this purpose, it requires photostable commercially available SF materials. Excited state dynamics in pure perylene film, ease of commercial production, is studied by time-resolved fluorescence and femtosecond transient absorption techniques under different photoexcitation energies. In film, polycrystalline regions contain perylene in H-type aggregate form. SF takes place from higher excited states of these aggregates in ultrafast time scale < 30 fs, reaching a triplet formation quantum yield of 108%. Moreover, at λex = 450 nm singlet fission was detected as a result of two-quantum absorption. Other competing relaxation channels are excimer (1 ps) and dimer radical cation formation (< 30 fs). Excimer radiatively relaxes within 19 ns and radical cation recombines in 3.2 ns. Besides, exciton self-trapping by crystal lattice distortions occurs within hundreds of picosecond. Our results highlight potential of simple-fabricated perylene films with similar properties as high-cost single crystal in SF based photovoltaic applications.

scholarly journals Magnetic field dependence of singlet fission in solutions of diphenyl tetracene

2015 ◽  
Vol 373 (2044) ◽  
pp. 20140323 ◽  
Author(s):  
Nicholas J. Thompson ◽  
Eric Hontz ◽  
Wendi Chang ◽  
Troy Van Voorhis ◽  
Marc Baldo
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Optoelectronic Devices ◽  
Magnetic Field Effects ◽  
Singlet Fission ◽  
Strong Fluorescence ◽  
Singlet Exciton ◽  
Fluorescence Modulation ◽  
Singlet Exciton Fission ◽  
Transfer State

Magnetic field effects provide a convenient and specific probe of singlet exciton fission within optoelectronic devices. Here, we demonstrate that this tool may also be applied to screen potential fission material candidates in solution. We characterize the phenomenon in diphenyl tetracene (DPT), which shows strong fluorescence modulation and the expected field dependence in its transient decay as a function of concentration. Solution measurements may also be used to test for the presence of an intermediate charge transfer state, but we observe no changes to the field dependence of DPT singlet exciton fission in toluene relative to chloroform.

scholarly journals Strategies for Design of Potential Singlet Fission Chromophores Utilizing a Combination of Ground State and Excited State Aromaticity Rules

2020 ◽  
Author(s):  
Ouissam El Bakouri ◽  
Joshua R. Smith ◽  
Henrik Ottosson
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Geometric Model ◽  
Substituent Effects ◽  
Singlet Fission ◽  
Singlet Exciton ◽  
Singlet Exciton Fission ◽  
Homo Lumo ◽  
Potential Use

Singlet exciton fission photovoltaics requires chromophores with their lowest excited states arranged so that 2<i>E</i>(T<sub>1</sub>) < <i>E</i>(S<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) < <i>E</i>(T<sub>2</sub>). Herein, qualitative theory and quantum chemical calculations are used to develop explicit strategies on how to use Baird’s 4<i>n</i> rule on excited state aromaticity, combined with Hückel’s 4<i>n</i>+2 rule for ground state aromaticity, to tailor new potential chromophores for singlet fission. We first analyze the <i>E</i>(T<sub>1</sub>), <i>E</i>(S<sub>1</sub>) and <i>E</i>(T<sub>2</sub>) of benzene and cyclobutadiene (<b>CBD</b>) as, respectively, excited state antiaromatic and aromatic archetypes, and reveal that <b>CBD </b>fulfils the criteria on the state ordering for a singlet fission chromophore. We then look at fulvenes, a class of compounds that can be tuned by choice of substituents from Baird-antiaromatic to Baird-aromatic in T<sub>1</sub> and S<sub>1</sub>, and from Hückel-aromatic to Hückel-antiaromatic in S<sub>0</sub>. The T<sub>1</sub> and S<sub>1</sub> states of most substituted fulvenes (159 of 225) are described by singly excited HOMO→LUMO configurations, providing a rational for the simultaneous tuning of <i>E</i>(T<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) along an approximate (anti)aromaticity coordinate. Key to the tunability is the exchange integral (K<sub>H,L</sub>), which ideally is constant throughout the compound class, providing a constant D<i>E</i>(S<sub>1</sub>-T<sub>1</sub>). This leads us to a geometric model for identification of singlet fission chromophores, and we explore what factors limit the model. Candidates with calculated <i>E</i>(T<sub>1</sub>) of ~1 eV or higher are identified among benzannelated 4<i>n</i>pi-electron compound classes and siloles. In brief, it is clarified how the joint utilization of Baird’s 4<i>n</i> and Hückel’s 4<i>n</i>+2 rules, together with substituent effects (electronic and steric) and benzannelation, can be used to tailor new chromophores with potential use in singlet fission photovoltaics.<br>

scholarly journals Strategies for Design of Potential Singlet Fission Chromophores Utilizing a Combination of Ground State and Excited State Aromaticity Rules

2020 ◽  
Author(s):  
Ouissam El Bakouri ◽  
Joshua R. Smith ◽  
Henrik Ottosson
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Geometric Model ◽  
Substituent Effects ◽  
Singlet Fission ◽  
Singlet Exciton ◽  
Singlet Exciton Fission ◽  
Homo Lumo ◽  
Potential Use

Singlet exciton fission photovoltaics requires chromophores with their lowest excited states arranged so that 2<i>E</i>(T<sub>1</sub>) < <i>E</i>(S<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) < <i>E</i>(T<sub>2</sub>). Herein, qualitative theory and quantum chemical calculations are used to develop explicit strategies on how to use Baird’s 4<i>n</i> rule on excited state aromaticity, combined with Hückel’s 4<i>n</i>+2 rule for ground state aromaticity, to tailor new potential chromophores for singlet fission. We first analyze the <i>E</i>(T<sub>1</sub>), <i>E</i>(S<sub>1</sub>) and <i>E</i>(T<sub>2</sub>) of benzene and cyclobutadiene (<b>CBD</b>) as, respectively, excited state antiaromatic and aromatic archetypes, and reveal that <b>CBD </b>fulfils the criteria on the state ordering for a singlet fission chromophore. We then look at fulvenes, a class of compounds that can be tuned by choice of substituents from Baird-antiaromatic to Baird-aromatic in T<sub>1</sub> and S<sub>1</sub>, and from Hückel-aromatic to Hückel-antiaromatic in S<sub>0</sub>. The T<sub>1</sub> and S<sub>1</sub> states of most substituted fulvenes (159 of 225) are described by singly excited HOMO→LUMO configurations, providing a rational for the simultaneous tuning of <i>E</i>(T<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) along an approximate (anti)aromaticity coordinate. Key to the tunability is the exchange integral (K<sub>H,L</sub>), which ideally is constant throughout the compound class, providing a constant D<i>E</i>(S<sub>1</sub>-T<sub>1</sub>). This leads us to a geometric model for identification of singlet fission chromophores, and we explore what factors limit the model. Candidates with calculated <i>E</i>(T<sub>1</sub>) of ~1 eV or higher are identified among benzannelated 4<i>n</i>pi-electron compound classes and siloles. In brief, it is clarified how the joint utilization of Baird’s 4<i>n</i> and Hückel’s 4<i>n</i>+2 rules, together with substituent effects (electronic and steric) and benzannelation, can be used to tailor new chromophores with potential use in singlet fission photovoltaics.<br>

Singlet Fission in Thin Solid Films of Bis(thienyl)diketopyrrolopyrroles

ChemPlusChem ◽  
2020 ◽  
Vol 85 (12) ◽  
pp. 2689-2703
Author(s):  
David Rais ◽  
Petr Toman ◽  
Jiří Pfleger ◽  
Udit Acharya ◽  
Yadu R. Panthi ◽  
...  
Keyword(s):  
Singlet Fission ◽  
Thin Solid Films ◽  
Solid Films

Strategies for Design of Potential Singlet Fission Chromophores Utilizing Baird's Rule on Excited State Aromaticity

2019 ◽  
Author(s):  
Ouissam El Bakouri ◽  
Joshua R. Smith ◽  
Henrik Ottosson
Keyword(s):  
Excited State ◽  
Excited States ◽  
Geometric Model ◽  
Substituent Effects ◽  
Singlet Fission ◽  
Singlet Exciton ◽  
Technology Platforms ◽  
Singlet Exciton Fission ◽  
Homo Lumo ◽  
Potential Use

In singlet exciton fission one photon of light is used to create two excitons of triplet multiplicity. This process requires chromophores with their lowest excited states arranged so that 2<i>E</i>(T<sub>1</sub>) < <i>E</i>(S<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) < <i>E</i>(T<sub>2</sub>). To match different technology platforms there is a high need for new candidate chromophores with the desired excited state orderings. Herein, qualitative theory and quantum chemical calculations are used to develop explicit strategies on how to use Baird’s 4n rule on excited state aromaticity to tailor new potential chromophores for singlet fission. We first analyze the <i>E</i>(T<sub>1</sub>), <i>E</i>(S<sub>1</sub>) and <i>E</i>(T<sub>2</sub>) of benzene and cyclobutadiene (CBD) as, respectively, excited state antiaromatic and aromatic archetypes, and reveal that CBD fulfils the criteria on the state ordering for a singlet fission chromophore. We then look at fulvenes, a class of compounds that can be tuned from Baird-antiaromatic to Baird-aromatic in T<sub>1</sub> and S<sub>1</sub> by choice of substituents. The T<sub>1</sub> and S<sub>1</sub> states of fulvenes are both described by singly excited HOMO→LUMO configurations, which provides a rational for the simultaneous and similar tuning of <i>E</i>(T<sub>1</sub>) and <i>E</i>(S<sub>1</sub>) along an approximate (anti)aromaticity coordinate. This leads us to a geometric model for identification of singlet fission chromophores. Candidates with calculated <i>E</i>(T<sub>1</sub>) of ~1 eV or higher are also identified among benzannelated 4<i>n</i>pi-electron compound classes and among siloles influenced to various extents by Baird-(anti)aromaticity in T<sub>1</sub> and S<sub>1</sub>. Finally, we explore the limitations of the design approach. In brief, it is clarified how Baird’s 4<i>n</i> rule together with substituent effects (electronic and steric) and benzannelation can be used to tailor new chromophores with potential use in singlet fission photovoltaics. <br>

scholarly journals Singlet exciton fission in a modified acene with improved stability and high photoluminescence yield

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Peter J. Budden ◽  
Leah R. Weiss ◽  
Matthias Müller ◽  
Naitik A. Panjwani ◽  
Simon Dowland ◽  
...  
Keyword(s):  
Radiative Decay ◽  
Energy Levels ◽  
Early Time ◽  
Electronic Energy ◽  
Chemical Degradation ◽  
Singlet Fission ◽  
Singlet Exciton ◽  
Improved Stability ◽  
Electronic Energy Levels ◽  
Singlet Exciton Fission

AbstractWe report a fully efficient singlet exciton fission material with high ambient chemical stability. 10,21-Bis(triisopropylsilylethynyl)tetrabenzo[a,c,l,n]pentacene (TTBP) combines an acene core with triphenylene wings that protect the formal pentacene from chemical degradation. The electronic energy levels position singlet exciton fission to be endothermic, similar to tetracene despite the triphenylenes. TTBP exhibits rapid early time singlet fission with quantitative yield of triplet pairs within 100 ps followed by thermally activated separation to free triplet excitons over 65 ns. TTBP exhibits high photoluminescence quantum efficiency, close to 100% when dilute and 20% for solid films, arising from triplet-triplet annihilation. In using such a system for exciton multiplication in a solar cell, maximum thermodynamic performance requires radiative decay of the triplet population, observed here as emission from the singlet formed by recombination of triplet pairs. Combining chemical stabilisation with efficient endothermic fission provides a promising avenue towards singlet fission materials for use in photovoltaics.

Lycopene crystalloids exhibit singlet exciton fission in tomatoes

2018 ◽  
Vol 20 (13) ◽  
pp. 8640-8646 ◽  
Author(s):  
M. J. Llansola-Portoles ◽  
K. Redeckas ◽  
S. Streckaité ◽  
C. Ilioaia ◽  
A. A. Pascal ◽  
...  
Keyword(s):  
Excited State ◽  
Transient Absorption ◽  
Singlet Exciton ◽  
Absorption Studies ◽  
Singlet Exciton Fission

Transient absorption studies conducted on in vitro lycopene aggregates, as well as on lycopene crystalloids inside tomato chromoplasts, reveal the appearance of a long-lived excited state, which we unambiguously identified as lycopene triplet generated by singlet exciton fission.

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