Singlet Fission in Pyrene‐Fused Azaacene Dimers

Mora‐Fuentes, Juan P.; Papadopoulos, Ilias; Thiel, Dominik; Álvarez‐Boto, Roberto; Cortizo‐Lacalle, Diego; Clark, Timothy; Melle‐Franco, Manuel; Guldi, Dirk M.; Mateo‐Alonso, Aurelio

doi:10.1002/anie.201911529

Cited by 33 publications

(43 citation statements)

References 41 publications

(9 reference statements)

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“…A likely rationale implies that the inter-DPP electronic coupling is weaker in m-DPP across the meta-position of the phenyl linker than across the ortho-position in o-DPP and, in turn, reduces TQY. [84,85] Finally, for p-DPP the shortest (S 1 S 0 ) Sol lifetime and subsequent population of (S 1 S 0 ) CT was observed. Despite this finding, no evidence for any significant triplet excited-state population was gathered.…”

Section: Time-resolved Characterizationmentioning

confidence: 80%

“…The overall strength of the interaction is expected to be the weakest among the DPP dimers, as the phenyl linker affords better electronic communication in case of ortho ‐ and para ‐substitutions. [ 84,85 ]…”

Section: Resultsmentioning

confidence: 99%

“…The overall strength of the interaction is expected to be the weakest among the DPP dimers, as the phenyl linker affords better electronic communication in case of ortho-and para-substitutions. [84,85] In low-temperature measurements with DPP-Ref at 80 K in 2-methyltetrahydrofuran (MeTHF) and in the presence of ethyliodide (EtI) to enhance the triplet formation, a 1185 nm feature was ascribed to phosphorescence. Correspondingly, a triplet excited state (T 1 ) energy of 1.04 eV was derived- Figure…”

Section: Steady-state Characterizationmentioning

confidence: 99%

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Solvent‐Dependent Singlet Fission in Diketopyrrolopyrrole Dimers: A Mediating Charge Transfer versus a Trapping Symmetry‐Breaking Charge Separation

Papadopoulos

Álvaro‐Martins

Molina

et al. 2020

Advanced Energy Materials

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photon management. SF enables multiple excitons to be generated after the absorption of just a single photon. [1-9] By integrating SF materials into solar-cell architectures, it is feasible to increase the overall efficiency of solar cells by pushing the Shockley-Queisser limit from 32% to approximately 45%. Several requirements must, however, be met to allow for efficient SF well beyond 100%. [10,11] Thermodynamically, the energy level of the singlet excited state (S 1) must be equal to or higher than twice that of the triplet excited state (T 1); (S 1) ≥ 2(T 1). [2,3,12] In addition, the energy levels of higher-lying triplet excited states (T 2) should exceed twice the energy of the lowest-lying triplet excited state; (T 2) ≥ 2(T 1). [2,3,12] The latter avoids (T 2) population as a product of triplet-triplet annihilation up-conversion (TTA-UC). [2,3,12] Sufficient electronic interaction between two or more chromophores is essential, and is usually realized for monomers by overlaps in the crystal packing or high concentrations in the solid state or solution, respectively. [12-16] Dimers, in which different spacers are employed to link the chromophores, rather than monomers, represent yet another strategy to adjust and fine-tune, for Three diketopyrrolopyrrole (DPP) dimers, linked via different dithienylphenylene spacers, ortho-DPP (o-DPP), meta-DPP (m-DPP), and para-DPP (p-DPP), are synthesized, characterized, and probed in light of intramolecular singlet fission (i-SF). Importantly, the corresponding DPP reference (DPP-Ref) singlet and triplet excited state energies of 2.22 and 1.04 eV, respectively, suggest that i-SF is thermodynamically feasible. The investigations focus on the impact of the relative positioning of the DPPs, and give compelling evidence that solvent polarity and/or spatial overlap govern i-SF dynamics and efficiencies. Polar solvents make the involvement of an intermediate charge transfer (CT) state possible, followed by the population of 1 (T 1 T 1) and subsequently (T 1 + T 1), while spatial overlap drives the mutual interactions between the DPPs. In o-DPP, the correct balance between polar solvents and spatial overlap leads to the highest triplet quantum yield (TQY) of 40%. Notable is the superimposition of CT and triplet excited states, preventing an accurate TQY determination. For m-DPP, poorer spatial overlap correlates with weaker CT character and manifests in a TQY of 11%. Strong CT character acts as a trap and prevents i-SF, as found with p-DPP. The DPP separation is decisive, enabling a symmetry-breaking charge-separated state rather than CT formation, shutting down the formation 1 (T 1 T 1).

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Section: Time-resolved Characterizationmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Steady-state Characterizationmentioning

confidence: 99%

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Solvent‐Dependent Singlet Fission in Diketopyrrolopyrrole Dimers: A Mediating Charge Transfer versus a Trapping Symmetry‐Breaking Charge Separation

Papadopoulos

Álvaro‐Martins

Molina

et al. 2020

Advanced Energy Materials

Self Cite

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“…Instead, this observation may be explained by a singlet fission mechanism populating triplet states that undergo a different, radiationless relaxation mechanism [46] . Previous work on substituted pentacene dimers, [47] covalently linked dimeric species of substituted pentacene [48] and N ‐heteropentacene [49] have demonstrated the ability of acenes to undergo efficient singlet fission relaxation pathways in solution.…”

Section: Resultsmentioning

confidence: 99%

High‐Resolution Electronic Excitation and Emission Spectra of Pentacene and 6,13‐Diazapentacene Monomers and Weakly Bound Dimers by Matrix‐Isolation Spectroscopy

Thusek

Hoffmann

Hübner

et al. 2020

Chemistry A European J

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N‐Heteropolycycles are among the most promising candidates for applications in organic devices. For this purpose, a profound understanding of the low‐energy electronic absorbance and emission characteristics is of crucial importance. Herein, we report high‐resolution absorbance and fluorescence spectra of pentacene (PEN) and 6,13‐diazapentacene (DAP) in solid neon obtained using the matrix‐isolation technique. Accompanying DFT calculations allow the assignment of specific vibrationally resolved signals to corresponding modes. Furthermore, we present for the first time evidence for the formation of van der Waals dimers of both substances. These dimers exhibit significantly different optical characteristics resulting from the change of electronic properties evoked by the incorporation of sp2 nitrogen into the molecular backbone.

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“…While there are examples for triptycene‐based PFPs, [19, 25] planar, star shaped PFPs [26] or phenylene bridged PFP dimers, [27] no TBTQ based analogue has been realized so far.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Optoelectronic Properties of a Quinoxalino‐Phenanthrophenazine (QPP) Extended Tribenzotriquinacene (TBTQ)

Ueberricke

Benke

Kirschbaum

et al. 2020

Chemistry A European J

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Singlet Fission in Pyrene‐Fused Azaacene Dimers

Cited by 33 publications

References 41 publications

Solvent‐Dependent Singlet Fission in Diketopyrrolopyrrole Dimers: A Mediating Charge Transfer versus a Trapping Symmetry‐Breaking Charge Separation

Solvent‐Dependent Singlet Fission in Diketopyrrolopyrrole Dimers: A Mediating Charge Transfer versus a Trapping Symmetry‐Breaking Charge Separation

High‐Resolution Electronic Excitation and Emission Spectra of Pentacene and 6,13‐Diazapentacene Monomers and Weakly Bound Dimers by Matrix‐Isolation Spectroscopy

Synthesis and Optoelectronic Properties of a Quinoxalino‐Phenanthrophenazine (QPP) Extended Tribenzotriquinacene (TBTQ)

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