Influence of core-twisted structure on singlet fission in perylenediimide film

Zhou, Jun; Liu, Heyuan; Wang, Weijie; Li, Tianyu; Li, Zhi; Liu, Zhaobin; Chen, Yanli; Dong, Yunqin; Li, Xiyou

doi:10.1016/j.jphotochem.2022.114473

Cited by 6 publications

(9 citation statements)

References 64 publications

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“…Here, the effects of CT resonance were also explored, with overall rates of 2.5–2.8 ns –1 being reported. Further 1 TT formation and separation rates in perylene diimide dimers are 3 ns –1 and 250 ns –1 reported by Zhou and co-workers, 0.05 ps –1 and 1 ps –1 reported by Kim and co-workers, and 1 ns –1 and 37 ns –1 reported by Schierl and co-workers …”

Section: Resultsmentioning

confidence: 99%

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Manian,

Campaioli,

Hudson

et al. 2023

Chem. Mater.

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The role of charge transfer states in multi-exciton mechanisms has recently become a point of discussion due to the difficulty associated with modeling their contributions accurately. Intermolecular packing has been shown experimentally to heavily influence multi-exciton mechanisms, and therefore understanding how this affects the coupling is key to controlling these processes. Using a gas phase perylene dimer in a weakly coupled configuration as a case study, we employ two separate methods to model the coupling between the bright and correlated triplet 1 TT states as a function of relative displacement. For singlet fission, displaced geometries are found to yield large charge transfer contributions within a wavefunction overlap paradigm, unlike for aligned geometries. Triplet−triplet annihilation charge transfer couplings are conversely very weak due to a large energy gap. We found that slipping of the dimer cofacial geometry is beneficial to both charge transfer-mediated processes within a wavefunction overlap scheme. However, within a fragment excitation difference (FED) scheme, a 1 Å slip is more beneficial than a 2 Å one. The resulting rates for singlet fission are in the femtosecond range, up to 22 ps −1 , while for triplet fusion they are in the nanosecond range, up to 707 μs −1 . By studying the dynamics of the triplet pair following singlet fission, we show that the decorrelation time scale depends on the nature of the relative molecular motion, ranging from picoseconds for fluctuations in the monomer orientations to microseconds for coplanar fluctuations. The direct comparison of the wavefunction overlap and FED methods yields an expected differential due to the method of calculation (linear-response vs multireference) but still strong agreement, suggesting that the more exact wavefunction overlap method can be substituted for the FED method in larger systems with minimal loss in accuracy vs computational complexity. These results provide a good stepping stone for further investigations into singlet fission related problems, correlating well with experiments despite the weakly coupled nature of the dimer.

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Section: Resultsmentioning

confidence: 99%

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Manian,

Campaioli,

Hudson

et al. 2023

Chem. Mater.

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“…■ RESULTS AND DISCUSSION Design and Characterization of MOF. To increase the solubility of ligand in polar reagents, 44 we chose the nonplanar halognenlized PDI as the organic linker (Figure S3), and then PDI-based MOFs were synthesized in the presence of Ni 2+ nodes via the solvothermal method. Structural analysis showed that the MOF material had the monoclinic space group C 2/c with a head-to-tail arrangement of PDI ligands (Figures 1a and S4).…”

Section: ■ Introductionmentioning

confidence: 99%

Ultrastable Anion Radicals in Ligand-Dimerized Frameworks for Self-Accumulated Electrochemiluminescence

Chen,

Gu,

et al. 2024

ACS Appl. Mater. Interfaces

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Electrochemiluminescence (ECL) is a light-emitting process that occurs via an annihilation reaction among energetic radical intermediates, whose stabilities determine the ECL efficiency. In this study, a ligand-dimerized metal–organic framework (MOF) with ultrastable anion radical is designed as an efficient nanoemitter for self-accumulated ECL. Due to the nonplanar structure of perylene diimide (PDI) derivate, two PDI ligands in the framework form a J-dimer unit with a vertical distance of ∼5.74 Å. In cathodic scanning, the ligand-dimerized MOF demonstrates three-step ECL emissions with a gradual increase in ECL intensity. Unlike the decrease in the PDI ligand, the self-accumulated ECL of the MOF was observed with 16.8-fold enhancement due to the excellent stability of radical intermediates in frameworks. Electron paramagnetic resonance demonstrated the ultrastability of free radicals in the designed frameworks, with 82.2% remaining even after one month of storage. Density functional theory calculations supported that PDI dimerization was energetically favorable upon successive electron injection. Moreover, the ECL wavelength is 610 nm, corresponding to the emission of excited dimers. The radical-stabilized reticular nanoemitters open up a new platform for decoding the fundamentals of self-accumulated ECL systems.

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“…To give PDIs different physical and chemical properties, substitutions are usually made at the bay area of the perylene core. The heteroatoms mainly used for substitution include halogen (Cl, Br, I) , and chalcogen (O, S, Se) atoms. , Se-substituted PDIs stand out due to their higher PCE, better charge transport capacity, and enhanced electron-accepting ability. − Meanwhile, Se is also widely used to improve the spin–orbit coupling (SOC) in organic materials, which can influence the generation of triplets through singlet fission , or intersystem crossing process. However, most of the studies concerning heteroatom-substituted PDIs focused on the characterization of OSC performance. ,,, Only a few studied the microscopic mechanism of photoelectric conversion, especially the generation of triplets. , …”

Section: Introductionmentioning

confidence: 99%

“…However, turning monomer molecules into covalent polymers may open up other channels that compete with the SF process, such as excimer emission. halogen (Cl, Br, I) 15,20 and chalcogen (O, S, Se) atoms. 29,30 Se-substituted PDIs stand out due to their higher PCE, better charge transport capacity, and enhanced electron-accepting ability.…”

Section: ■ Introductionmentioning

confidence: 99%

Promotion of Fast and Efficient Singlet Fission Process of PDI Dimers by Selenium Substitution

Yang,

Su,

Wang

et al. 2024

J. Phys. Chem. B

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Singlet fission (SF) is a triplet generation mechanism capable of turning a singlet exciton into two triplet excitons. It has the potential to enhance the power conversion efficiency of single-junction solar cells. Perylene diimides (PDIs) are a class of dye molecules with photovoltaic properties and are beginning to receive more and more attention due to their potential for SF. Here, we report a selenium-substituted PDI dimer, Se-PDI-II, and we studied its SF mechanism by using steady-state, transient absorption, and time-resolved photoluminescence spectroscopy. Compared with the unsubstituted dimer PDI-II, we found that the introduction of selenium atoms can suppress excimer emission during the SF process, showing much higher SF efficiency and triplet yield.

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Influence of core-twisted structure on singlet fission in perylenediimide film

Cited by 6 publications

References 64 publications

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Ultrastable Anion Radicals in Ligand-Dimerized Frameworks for Self-Accumulated Electrochemiluminescence

Promotion of Fast and Efficient Singlet Fission Process of PDI Dimers by Selenium Substitution

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