Morphology‐Independent Efficient Singlet Exciton Fission in Perylene Diimide Thin Films

Aulin, Yaroslav V.; Felter, Kevin M.; Günbaş, Duygu D.; Dubey, Rajeev K.; Jager, Wolter F.; Grozema, Ferdinand C.

doi:10.1002/cplu.201700449

Cited by 38 publications

(47 citation statements)

References 32 publications

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“…The shorter fluorescence lifetime of excitons in PDI-octyl may be another indication of its improved packing as PDI-hexhep has a fluorescence lifetime that is more similar to that in solution ( τ EXC = 4.5 ns). 4…”

Section: Resultsmentioning

confidence: 99%

Interplay between Charge Carrier Mobility, Exciton Diffusion, Crystal Packing, and Charge Separation in Perylene Diimide-Based Heterojunctions

Felter

Caselli

Günbaş

et al. 2019

ACS Appl. Energy Mater.

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Two of the key parameters that characterize the usefulness of organic semiconductors for organic or hybrid organic/inorganic solar cells are the mobility of charges and the diffusion length of excitons. Both parameters are strongly related to the supramolecular organization in the material. In this work we have investigated the relation between the solid-state molecular packing and the exciton diffusion length, charge carrier mobility, and charge carrier separation yield using two perylene diimide (PDI) derivatives which differ in their substitution. We have used the time-resolved microwave photoconductivity technique and measured charge carrier mobilities of 0.32 and 0.02 cm2/(Vs) and determined exciton diffusion lengths of 60 and 18 nm for octyl- and bulky hexylheptyl-imide substituted PDIs, respectively. This diffusion length is independent of substrate type and aggregate domain size. The differences in charge carrier mobility and exciton diffusion length clearly reflect the effect of solid-state packing of PDIs on their optoelectronic properties and show that significant improvements can be obtained by effectively controlling the solid-state packing.

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Section: Resultsmentioning

confidence: 99%

Interplay between Charge Carrier Mobility, Exciton Diffusion, Crystal Packing, and Charge Separation in Perylene Diimide-Based Heterojunctions

Felter

Caselli

Günbaş

et al. 2019

ACS Appl. Energy Mater.

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“…For free CsPbBr 3 NPLs, no changes in the absorption are observed, as expected, since the NPLs do not absorb at 510 nm. For isolated PDI molecules, the TA spectrum exhibits the typical features of the PDI excited state (PDI*): a bleach of the ground state absorption at wavelengths between 470 and 540 nm, stimulated emission at~580 nm and a broad photoinduced absorption (PA) from 690 to 900 nm with a narrow maximum at 800 nm 31,44,46 . PDI* decays with a time constant of 4 ns, which is close to the fluorescence lifetime determined for this compound of τ rad = 3.8 ns ( Supplementary Fig.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Overcoming the exciton binding energy in two-dimensional perovskite nanoplatelets by attachment of conjugated organic chromophores

et al. 2020

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In this work we demonstrate a novel approach to achieve efficient charge separation in dimensionally and dielectrically confined two-dimensional perovskite materials. Twodimensional perovskites generally exhibit large exciton binding energies that limit their application in optoelectronic devices that require charge separation such as solar cells, photodetectors and in photo-catalysis. Here, we show that by incorporating a strongly electron accepting moiety, perylene diimide organic chromophores, on the surface of the twodimensional perovskite nanoplatelets it is possible to achieve efficient formation of mobile free charge carriers. These free charge carriers are generated with ten times higher yield and lifetimes of tens of microseconds, which is two orders of magnitude longer than without the peryline diimide acceptor. This opens a novel synergistic approach, where the inorganic perovskite layers are combined with functional organic chromophores in the same material to tune the properties for specific applications.

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“…[12,[19][20][21][22][23][24][25][26][27] Acenes, in general, and pentacenes in particular, fulfill all SF requirements and, consequently have attracted a great deal of attention. [16,24,[28][29][30][31][32][33][34][35] Other promising SF materials include rylene diimides [26,[36][37][38][39][40][41][42][43][44] and diketopyrrolopyrroles (DPPs). [45][46][47][48][49][50][51] Incentives for this study were to improve our understanding of intramolecular SF (i-SF) in DPP dimers.…”

Section: Introductionmentioning

confidence: 99%

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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Morphology‐Independent Efficient Singlet Exciton Fission in Perylene Diimide Thin Films

Cited by 38 publications

References 32 publications

Interplay between Charge Carrier Mobility, Exciton Diffusion, Crystal Packing, and Charge Separation in Perylene Diimide-Based Heterojunctions

Interplay between Charge Carrier Mobility, Exciton Diffusion, Crystal Packing, and Charge Separation in Perylene Diimide-Based Heterojunctions

Overcoming the exciton binding energy in two-dimensional perovskite nanoplatelets by attachment of conjugated organic chromophores

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

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