Dynamics of singlet fission and electron injection in self-assembled acene monolayers on titanium dioxide

Pace, Natalie A.; Arias, Dylan H.; Granger, Devin B.; Christensen, Steven T.; Anthony, John E.; Johnson, Justin C.

doi:10.1039/c7sc04688j

Cited by 46 publications

(76 citation statements)

References 70 publications

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“…6). The 900 nm feature is consistent with previously-reported cation absorption peak of triisopropylsilylethynyl tetracene carboxylic acid (TIPS-TCA) at~930 nm 46 . Moreover, its formation kinetics is consistent with the decay of the XB within 50 ps.…”

Section: Resultssupporting

confidence: 90%

“…The difference spectra are dominated by the XB feature of NCs which exhibits a faster recovery than free NCs. At very long delay times (~30 μs), photoinduced absorption features corresponding to the triplets of tetracene ( 3 TCA*) 28,46 are clearly detected, confirming triplet sensitization or TET from NCs to TCA. However, detailed kinetic analysis is required to uncover the interplay between TET, FRET, hole transfer and hole trapping.…”

Section: Resultsmentioning

confidence: 80%

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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: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 80%

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

et al. 2020

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“…The energetic offset and broadening between the two spectra has previously been observed in other strongly-coupled acene thin lms and underscores the strong coupling that perturbs even fairly localized triplet states. 26,27 There are no triplet features in the sensitized triplet spectrum in the near-IR, which affirms the assignment of observed long-lived bands to the (TT) state in the directly excited lm.…”

Section: Transient Absorption Spectroscopysupporting

confidence: 81%

Conversion between triplet pair states is controlled by molecular coupling in pentadithiophene thin films

et al. 2020

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“…As a consequence, significant contributions from open-shell resonances in the ground state are frequently observed 16 . Keywords that highlight acene-type PAHs with zig-zag periphery range from singlet fission 17 – 21 , auspicious charge carrier mobilities 22 , 23 , to amplified spontaneous emission 24 , and enlarge the interest in PAHs by the fields of spintronics and molecular magnetism 25 - 27 . Recently, various research groups reported on substituted angularly fused-tetracenes 28 – 32 , which overcome the low stability of linear acenes, by increasing the intrinsic number of Clar’s-sextets 33 .…”

Section: Introductionmentioning

confidence: 99%

Dehydrative π-extension to nanographenes with zig-zag edges

et al. 2018

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Zig-zag nanographenes are promising candidates for the applications in organic electronics due to the electronic properties induced by their periphery. However, the synthetic access to these compounds remains virtually unexplored. There is a lack in efficient and mild strategies origins in the reduced stability, increased reactivity, and low solubility of these compounds. Herein we report a facile access to pristine zig-zag nanographenes, utilizing an acid-promoted intramolecular reductive cyclization of arylaldehydes, and demonstrate a three-step route to nanographenes constituted of angularly fused tetracenes or pentacenes. The mild conditions are scalable to gram quantities and give insoluble nanostructures in close to quantitative yields. The strategy allows the synthesis of elusive low bandgap nanographenes, with values as low as 1.62 eV. Compared to their linear homologues, the structures have an increased stability in the solid-state, even though computational analyses show distinct diradical character. The structures were confirmed by X–ray diffraction or scanning tunneling microscopy.

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Dynamics of singlet fission and electron injection in self-assembled acene monolayers on titanium dioxide

Abstract: Electron injection competes with singlet fission in disordered monolayers of tetracene and pentacene-based dyes on mesoporous TiO2 photoelectrodes.

Cited by 46 publications

References 70 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

Conversion between triplet pair states is controlled by molecular coupling in pentadithiophene thin films

Dehydrative π-extension to nanographenes with zig-zag edges

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