Intramolecular singlet fission and triplet exciton harvesting in tetracene oligomers for solar energy conversion

Wang, Tianying; Liu, Heyuan; Wang, Xianyuan; Tang, Ling‐Long; Zhou, Jun; Song, Xiaojuan; Lv, Liping; Chen, Wenmiao; Chen, Yanli; Li, Xiyou

doi:10.1039/d3ta00193h

Cited by 11 publications

(12 citation statements)

References 224 publications

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“…[9,11,14,20,44,52,58,[67][68][69][70] In general, delocalization plays a major role in the dynamics of SF, as it is not only relevant for the triplet dissociation, but also for the initial event of SF. [71] As triplet excited states are more localized compared to singlet excited states (which translates to an increased number of available microstates for 1 (T 1 T 1 ) compared to (S 1 S 0 )), the first event of SF also entails a gain in entropy in extended systems. [51,63] Such effects are, however, predominantly observed in solidstate systems, and they are less significant in solution where excited states are confined within the molecular structure.…”

Section: Introductionmentioning

confidence: 99%

“…In general, delocalization plays a major role in the dynamics of SF, as it is not only relevant for the triplet dissociation, but also for the initial event of SF [71] . As triplet excited states are more localized compared to singlet excited states (which translates to an increased number of available microstates for 1 (T 1 T 1 ) compared to (S 1 S 0 )), the first event of SF also entails a gain in entropy in extended systems [51,63] .…”

Section: Introductionmentioning

confidence: 99%

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Intramolecular Triplet Diffusion Facilitates Triplet Dissociation in a Pentacene Hexamer

Greißel,

Thiel,

Gotfredsen

et al. 2024

Angew Chem Int Ed

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Triplet dynamics in singlet fission depend strongly on the strength of the electronic coupling. Covalent systems in solution offer precise control over such couplings. Nonetheless, efficient free triplet generation remains elusive in most systems, as the intermediate triplet pair 1(T1T1) is prone to triplet‐triplet annihilation due to its spatial confinement. In the solid state, entropically driven triplet diffusion assists in the spatial separation of triplets, resulting in higher yields of free triplets. Control over electronic coupling in the solid state is, however, challenging given its sensitivity to molecular packing. We have thus developed a hexameric system (HexPnc) to enable solid‐state‐like triplet diffusion at the molecular scale. This system is realized by covalently tethering three pentacene dimers to a central subphthalocyanine scaffold. Transient absorption spectroscopy, complemented by theoretical structural optimizations and steady‐state spectroscopy, reveals that triplet diffusion is indeed facilitated due to intramolecular aggregation. The yield of free triplets in HexPnc is increased by a factor of up to 14 compared to the corresponding dimeric reference (DiPnc). Thus, HexPnc establishes crucial design aspects for achieving efficient triplet dissociation in strongly coupled systems by providing avenues for diffusive separation of 1(T1T1), while, concomitantly, retaining strong interchromophore coupling without compromising rapid 1(T1T1) formation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intramolecular Triplet Diffusion Facilitates Triplet Dissociation in a Pentacene Hexamer

Greißel,

Thiel,

Gotfredsen

et al. 2024

Angew Chem Int Ed

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“…Condition 2 would prevent the triplettriplet annihilation (TTA) process. 10 Although many efforts have been devoted, the number of SF chromophores is still limited, 11,12 which greatly hinders the basic research and practical application of SF. Therefore, it is necessary and urgent to expand the molecular library of SF chromophores.…”

Section: Introductionmentioning

confidence: 99%

Potential singlet fission chromophores of azulene-containing tetracene analogues: a theoretical study

Li,

Shen,

Wang

et al. 2023

J. Mater. Chem. C

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“…32% to over 45%. , When SF occurs, a chromophore in its singlet excited state (S 1 ) interacts with a nearby chromophore in its ground state (S 0 ), forming a spin-correlated triplet pair state 1 (T 1 T 1 ). − Subsequently, the triplet pair can undergo decorrelation, resulting in two noninteracting, free triplet states (T 1 + T 1 ). These triplets are then available for completing the process of solar energy conversion. ,− …”

Section: Introductionmentioning

confidence: 99%

Catalyzing Singlet Fission by Transition Metals: Second versus Third Row Effects

Hou,

Papadopoulos,

et al. 2023

Precision Chemistry

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The synthesis and characterization of platinum(II) and palladium(II) complexes bearing two (dimers Pt(Lpc)2Cl2 and Pd(Lpc)2Cl2), one (monomers Pt(Lpc)(Lref)Cl2 and Pd(Lpc)(Lref)Cl2), or no (reference compounds Pt(Lref)2Cl2 and Pd(Lref)2Cl2) pentacene-based pyridyl ligands are presented. Photophysical properties of the dimers are probed by means of steady-state and time-resolved transient absorption measurements in comparison to the monomer and model compounds. Our results document that despite enhanced spin–orbit coupling from the presence of heavy atoms, intramolecular singlet fission (iSF) is not challenged by intersystem crossing. iSF thus yields correlated triplet pairs and even uncorrelated triplet excited states upon decoherence. Importantly, significant separation of the two pentacenyl groups facilitates decoupling of the two chromophores. Furthermore, the mechanism of iSF is altered depending on the respective metal center, that is, Pt(II) versus Pd(II). The dimer based on Pt(II), Pt(Lpc)2Cl2, exhibits a direct pathway for the iSF and forms a correlated triplet pair with singlet–quintet spin-mixing within 10 ns in variable solvents. On the other hand, the dimer based on Pd(II), Pd(Lpc)2Cl2, leads to charge transfer mixing during the population of the correlated triplet pair that is dependent on solvent polarity. Moreover, Pd(Lpc)2Cl2 gives rise to a stable equilibrium between singlet and quintet correlated triplet pairs with lifetimes of up to 170 ns. Inherent differences in the size and polarizability, when contrasting platinum(II) with palladium(II), are the most likely rationale for the underlying trends.

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Intramolecular singlet fission and triplet exciton harvesting in tetracene oligomers for solar energy conversion

Abstract: Singlet fission (SF), which could convert one singlet exciton into two triplet excitons, has the potential for enhancing the solar energy conversion efficiency, such as photovoltaic cell and photocatalysis. Recently,...

Cited by 11 publications

References 224 publications

Intramolecular Triplet Diffusion Facilitates Triplet Dissociation in a Pentacene Hexamer

Intramolecular Triplet Diffusion Facilitates Triplet Dissociation in a Pentacene Hexamer

Potential singlet fission chromophores of azulene-containing tetracene analogues: a theoretical study

Catalyzing Singlet Fission by Transition Metals: Second versus Third Row Effects

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