Polymorphism influences singlet fission rates in tetracene thin films

Arias, Dylan H.; Ryerson, Joseph L.; Cook, Jasper D.; Damrauer, Niels H.; Johnson, Justin C.

doi:10.1039/c5sc03535j

Cited by 120 publications

(172 citation statements)

References 56 publications

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“…12 The S 1 state of Tc decays predominantly via SF in evaporated polycrystalline films, on a timescale of 10-100 ps, and the triplet lifetime is around 500 ns. 15,46 The limiting efficiency of a Tc/c-Si hybrid solar cell similar to those reported here has been calculated to be 35.8%, 56 while the Auger limit of a normal silicon cell is 29.4%. 3 This demonstrates the potential for singlet fission to improve an alreadyefficient solar cell technology.…”

Section: Introductionsupporting

confidence: 60%

“…12 Xia and coworkers have prepared a comprehensive review of recent progress in SF materials and devices. 13 Reports of SF have been made for many material systems: in thin films, [14][15][16][17] nanoparticles, [18][19][20] 16,23,27,28 From the perspective of a photovoltaics application, however, the utility of SF as a means of increasing photocurrent by reducing thermalisation is clear. Over the past decade, a number of groups have reported solar cells incorporating SF materials.…”

Section: Introductionmentioning

confidence: 99%

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Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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Singlet exciton fission is an exciton multiplication process that occurs in certain organic materials, converting the energy of single highly-energetic photons into pairs of triplet excitons. This could be used to boost the conversion efficiency of crystalline silicon solar cells by creating photocurrent from energy that is usually lost to thermalisation. An appealing method of implementing singlet fission with crystalline silicon is to incorporate singlet fission media directly into a crystalline silicon device. To this end, we developed a solar cell that pairs the electron-selective contact of a high-efficiency silicon heterojunction cell with an organic singlet fission material, tetracene, and a PEDOT:PSS hole extraction layer. Tetracene and n-type crystalline silicon meet in a direct organic-inorganic heterojunction. In this concept the tetracene layer selectively absorbs blue-green light, generating triplet pairs that can dissociate or resonantly transfer at the organo-silicon interface, while lower-energy light is transmitted to the silicon absorber. UV photoemission measurements of the organicinorganic interface showed an energy level alignment conducive to selective hole extraction from silicon by the organic layer. This was borne out by current-voltage measurements of devices subsequently produced. In these devices, the silicon substrate remained well-passivated beneath the tetracene thin film. Light absorption in the tetracene layer created a net reduction in current for the solar cell, but optical modelling of the external quantum efficiency spectrum suggested a small photocurrent contribution from the layer. This is a promising first result for the direct heterojunction approach to singlet fission on crystalline silicon.

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Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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“…The similarity of these results is despite Tarasov et al using much thicker films than those used here and confirms the independence of singlet fission dynamics upon film thickness. [43] The MPL measurement for polycrystalline rubrene also showed a large decrease in photoluminescence (−11.6%) at low magnetic field followed by a monotonic increase approaching 0% MPL at high magnetic field (Figure 3), again, in good agreement with similar measurements by Tarasov et al [48] In preparation for MPL imaging, Hall sensor imaging of the magnetic field above the permanent magnets was undertaken (Figure 4), which, for the pair of cubic magnets with their poles oriented in-plane (Figure 4b,d), showed a bipolar field profile with a measured peak field of ±247 mT. The ring-shaped magnet, with its poles oriented out-of-plane, showed an asymmetrical field intensity with a peak field of +299 mT.…”

Section: Resultsmentioning

confidence: 99%

Wide Field Magnetic Luminescence Imaging

Hodges

Grell

Morley

et al. 2017

Adv Funct Materials

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This study demonstrates how magnetic-field-dependent luminescence from organic films can be used to image the magnetic configuration of an underlying sample. The organic semiconductors tetracene and rubrene exhibit singlet exciton fission, which is a process sensitive to magnetic fields. Here, thin films of these materials were characterized using photoluminescence spectrometry, atomic force microscopy, and photoluminescence magnetometry. The luminescence from these substrate-bound thin films is imaged to reveal the magnetic configuration of underlying Nd-Fe-B magnets. The tendency of rubrene to form amorphous films and produce large changes in photoluminescence under an applied magnetic field makes it more appropriate for magnetic field imaging than tetracene. This demonstration can be extended in the future to allow simple microscopic imaging of magnetic structure.

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“…This is particularly clear when comparing it to polycrystalline Tc films, where similar or even more endergonic reaction thermodynamics (ΔE SF ≈ 0.1 eV) are in place, but where fission occurs ∼3 orders of magnitude faster. 13,14,73 There are, we believe, two significant drivers for these comparative differences. First, in BT1 in solution, one can expect a substantial reorganization energy (λ tot ) for the reaction from S 1 to 1 TT that is likely absent in the crystal.…”

Section: Introductionmentioning

confidence: 92%

Solution-Phase Singlet Fission in a Structurally Well-Defined Norbornyl-Bridged Tetracene Dimer

2016

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The photophysics of a norbornyl-bridged covalent tetracene (Tc) dimer BT1 and a monomer analogue Tc-e were studied in room-temperature nonpolar solvents. Notably in BT1, a Davydov-split band is observed in UV absorption, heralding interchromophore electronic interactions. Emission spectra indicate an acene-like vibronic progression mirroring the lowest-energy visible absorption. For BT1, this argues against excited-state excimer formation. Evidence of intramolecular singlet fission (SF) comes from a comparison of time-resolved emission decay signals collected for BT1 versus Tc-e in toluene. In BT1, the multiexcitonic (1)TT state is produced in 70 ns in 6% yield. A ratio of fission versus fusion rate constants provides an experimental measure of the SF reaction free energy at 52 meV in good agreement with previous calculations. The low SF yield corroborates our expectations that orbital symmetry effects on diabatic coupling for SF are important for dimers that cannot rely on more favorable thermodynamics.

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Polymorphism influences singlet fission rates in tetracene thin films

Abstract: We report the effect of crystal structure and crystallite grain size on singlet fission (SF) in polycrystalline tetracene, one of the most widely studied SF and organic semiconductor materials.

Cited by 120 publications

References 56 publications

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Wide Field Magnetic Luminescence Imaging

Solution-Phase Singlet Fission in a Structurally Well-Defined Norbornyl-Bridged Tetracene Dimer

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