Diphenylisobenzofuran Bound to Nanocrystalline Metal Oxides: Excimer Formation, Singlet Fission, Electron Injection, and Low Energy Sensitization

Banerjee, Tanmay; Hill, Sean P.; Hermosilla-Palacios, M. Alejandra; Piercy, Brandon D.; Haney, Jess; Casale, Bryan; DePrince, A. Eugene; Losego, Mark D.; Kleiman, Valeria D.; Hanson, Kenneth

doi:10.1021/acs.jpcc.8b08599

Cited by 22 publications

(37 citation statements)

References 88 publications

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“…For both NCA and TCA, only their oxidation potential energies (E ox ) could be determined from CV in the used electrochemical window ( Supplementary Figs. 2, 3) and their reduction potential energies (E red ) were approximated as 3,34,35 : E red = E ox + E g , with E g being the optical gaps of the molecules. Similarly, the reduction potential energies to form molecular triplets (E red,T ) were approximated as 3,34,35 : E red,T = E ox + E T , with E T being the triplet energies.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface

et al. 2020

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The mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface remain poorly understood. Many seemingly contradictory results have been reported, mainly because of the complicated trap states characteristic of inorganic semiconductors and the ill-defined relative energetics between semiconductors and molecules used in these studies. Here we clarify the transfer mechanisms by performing combined transient absorption and photoluminescence measurements, both with sub-picosecond time resolution, on model systems comprising lead halide perovskite nanocrystals with very low surface trap densities as the triplet donor and polyacenes which either favour or prohibit charge transfer as the triplet acceptors. Hole transfer from nanocrystals to tetracene is energetically favoured, and hence triplet transfer proceeds via a charge separated state. In contrast, charge transfer to naphthalene is energetically unfavourable and spectroscopy shows direct triplet transfer from nanocrystals to naphthalene; nonetheless, this "direct" process could also be mediated by a high-energy, virtual charge-transfer state.

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Section: Resultsmentioning

confidence: 99%

Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface

et al. 2020

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“…The excited-state dynamics of molecular aggregates is a rich and complex subject, as there are a multitude of potential photophysical pathways available after photoexcitation, such as symmetry-breaking charge separation (SB-CS), excimer formation, and singlet fission. − Better knowledge and understanding of these processes and their origins may lead to the ability to direct exciton and charge flow in a molecular solid, which is very important for harvesting solar energy. For example, a major difference between inorganic semiconductors, such as silicon, and organic semiconductors is the inability of the latter to use photons having near-bandgap energies to generate electron–hole pairs without significant energy losses or resorting to employing a secondary electron donor or acceptor.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Dynamics of Perylene-Based Chromophore Assemblies on Nanoporous Anodic Aluminum Oxide Membranes

et al. 2021

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Exploring excited-state decay pathways in organic chromophore assemblies often requires significant synthetic effort to systematically change interchromophore distances. Moreover, the solubility of these assemblies is often limited. Herein, we examine how nanoporous anodic aluminum oxide (AAO) membranes can address both of these issues by covalently attaching 3-(phenylethynyl)perylene (PEP) and 1,6,7,12-tetrakis-(4-tert-butylphenoxy)perylene(3,4:9,10)-bis(dicarboximide) (tpPDI) chromophores with different loadings to AAO membranes, where the estimated average distance between chromophores on the AAO membranes for PEP-AAO-1, -2, and -3 is 5, 8, and 16 Å, respectively, while that between tpPDI cores in tpPDI-AAO-1, -2, -3, and -4 is 4, 6, 10, and 17 Å, respectively. When PEP-AAO-1, -2, and -3 are photoexcited, we observe a distribution of excimer-like states with varying degrees of charge-transfer (CT) character depending on the interchromophore spacing and solvent polarity. Increasing solvent polarity or decreasing the interchromophore distance increases the CT character in the excimer state. Notably, a PEP excimer state having significant CT character still forms in air, that is, in the absence of solvent. In contrast, when tpPDI-AAO-1 is photoexcited in solvents of varying polarity, as well as in air, we observe full symmetry-breaking charge separation (SB-CS) between tpPDIs attached to the AAO membrane. The SB-CS and charge recombination rates increase with increasing solvent polarity as the energy of the CT state is lowered. As the average distance between the tpPDIs increases in the series tpPDI-AAO-1, -2, -3, and -4, the SB-CS rate decreases with no SB-CS observed in tpPDI-AAO-4. This demonstrates the utility of AAO membranes to control the fate of electronic excited states by tuning the various contributions from Coulombic and charge transfer coupling.

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“…Recently, there has been an increase in research into the field of chromophore ligands attached to nanocrystal quantum dots 56 − 59 or semiconductor scaffolds, 60 in particular, the replacement of ligands that offer colloidal stability with ones that add additional optoelectronic properties. These ligands have potential applications for increased solar absorption, efficient transport of excitations, upconversion, and singlet fission.…”

Section: Introductionmentioning

confidence: 99%

Excimer Formation in Carboxylic Acid-Functionalized Perylene Diimides Attached to Silicon Dioxide Nanoparticles

et al. 2019

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The creation of artificial light-harvesting complexes involves the ordered arrangement of chromophores in space. To guarantee efficient energy-transfer processes, organic dyes must be brought into close proximity, often leading to aggregation and the formation of excimer states. In recent years, the attachment of ligand-based chromophores to nanoparticles has also generated interest in relation to improved solar harvesting and spin-dependent electronic interactions such as singlet fission and upconversion. We explore the covalent attachment of two novel perylene-diimide (PDI) carboxylic acid ligands to silicon dioxide nanoparticles. This allows us to study electronic interactions between the ligands when attached to nanoparticles because these cannot couple to the wide band gap silicon dioxide. One of the synthesized PDI ligands has sterically hindering phenols in the bay position and undergoes minimal optical changes upon attachment, but the other forms an excimer state with a red-shifted and long-lived florescence. As such, molecular structure changes offer a method to tune weak and strong interactions between ligand layers on nanocrystal surfaces.

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Diphenylisobenzofuran Bound to Nanocrystalline Metal Oxides: Excimer Formation, Singlet Fission, Electron Injection, and Low Energy Sensitization

Cited by 22 publications

References 88 publications

Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface

Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface

Excited-State Dynamics of Perylene-Based Chromophore Assemblies on Nanoporous Anodic Aluminum Oxide Membranes

Excimer Formation in Carboxylic Acid-Functionalized Perylene Diimides Attached to Silicon Dioxide Nanoparticles

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