Singlet fission from upper excited singlet states and polaron formation in rubrene film

Wu, Tong; Ni, Wenjun; Gurzadyan, Gagik G.; Sun, Licheng

doi:10.1039/d0ra10780h

Cited by 17 publications

(31 citation statements)

References 71 publications

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“…The polaron-related PIA at 550 nm is similarly fit with a rise time of trise = 250 ps (Figure 3c, bottom), and begins to decay within our measurement window. We attribute this to triplet formation through the polaron state, 43,51 which is further supported by the increased intensity of the rubrene polaron feature relative to the T1 à Tn transition in MAFA/rub than in the rubrene thin film (Figure S1b) and the visible decay of the polaron state within our measurement window.…”

supporting

confidence: 71%

“…35 In the MAFA/rub device, additional overlapping PIAs are observed at ~ 480 nm, 520 nm, and 550 nm, which correspond to the rubrene triplet excited state T1 à Tn transitions and polaron signature, respectively (compare Figure S1). [41][42][43][44] The excited state triplet absorption signal in MAFA/rub confirms the rubrene triplet sensitization under 700 nm excitation. Comparing the TA surfaces of MAFA and MAFA/rub in Figure 1c,d and the extracted spectra in Figure 1e,f, we find no additional unexpected absorbing features in the presence of rubrene within the measurement window.…”

supporting

confidence: 58%

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Ultrafast Triplet Generation at the Lead Halide Perovskite/Rubrene Interface

Conti

Bieber

VanOrman

et al. 2021

Preprint

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Triplet sensitization of rubrene by bulk lead halide perovskites has recently resulted in efficient infrared-to-visible photon upconversion via triplet-triplet annihilation. Notably, this process occurrs under solar relavant fluxes, potentially paving the way toward integration with photovoltaic devices. In order to further improve the upconversion efficiency, the fundamental photophysical pathways at the perovskite/rubrene interface must be clearly understood to maximize charge extraction. Here, we utilize ultrafast transient absorption spectroscopy to elucidate the processes underlying the triplet generation at the perovskite/rubrene interface. Based on the bleach and photoinduced absorption features of the perovskite and perovskite/rubrene devices obtained at multiple pump wavelengths and fluences, along with their resultant kinetics, our results do not support charge transfer states or long-lived trap states as the underlying mechanism. Instead, the data points towards a triplet sensitization mechanism based on rapid extraction of thermally excited carriers on the picosecond timescale.

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supporting

confidence: 71%

supporting

confidence: 58%

Ultrafast Triplet Generation at the Lead Halide Perovskite/Rubrene Interface

Conti

Bieber

VanOrman

et al. 2021

Preprint

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“…The major focus in SF studies was on polyacenes such as pentacene, tetracene, and rubrene. − However, their triplet states are quite low-lying, i.e., 0.86 eV (pentacene), 1.2 eV (tetracene), and 1.1 eV (rubrene), which hinders their applications in perovskite or dye-sensitized-based solar cells. Perylene exhibits strong absorptivity in the UV–vis spectral region and thermal and photochemical stability and has wide application in organic electronic and photovoltaic devices .…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Singlet Fission Yield by Hindering Excimer Formation in Perylene Film

Zhang

et al. 2021

J. Phys. Chem. C

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Singlet fission (SF), the spin-allowed process of converting one singlet exciton into two triplet excitons, holds promise for increasing the efficiency of solar cells. Other processes, namely, excimer formation, are regarded as a competing channel of relaxation for SF. In this work, a film of perylene derivative, 2,5,8,11-tetra-tert-butylperylene (TBPe), was prepared to investigate the influence of four tert-butyl groups on the film molecular packing and SF efficiency. In the TBPe film, excimer formation was found to be fully suppressed. Moreover, SF takes place from the upper vibrational states of S1, reaching the highest triplet quantum yield of 1.85. Quantum chemical calculations reveal that the spatial configuration of perylene aggregation plays a key role in tuning the ratio between excimer formation and SF. When the steric hindrance of the tert-butyl groups leads to a slip-stacking spatial arrangement for dimers, it blocks the competing excimer generation and enhances the SF process.

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“…The lifetimes of singlet excited states obtained from global fit are similar to 400 nm: τ 1 = 4.9 ps and τ 2 = 110 ps. From TA spectra, we cannot get any sign of polaron, charges, or ionization, as was observed in our previous studies with similar organic films. − …”

Section: Resultsmentioning

confidence: 55%

Switching Pathways of Triplet State Formation by Twisted Intramolecular Charge Transfer

Zhou

Lunchev

et al. 2021

J. Phys. Chem. B

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With the aim of constructing efficient photoelectric organic materials, a pyrido[3,2-g]quinoline derivative named LA17b has been synthesized, and its photodynamic relaxation processes in solvents and films were studied by time-resolved fluorescence and femtosecond transient absorption techniques. The steady-state fluorescence spectra show pronounced red-shift with the increase of the solvent polarity as well as in binary solvent hexane/ethanol by increasing ethanol concentration. However, the strong red-shift does not lead to quenching of the fluorescence. This is explained in terms of a twisted intramolecular charge transfer (TICT) state. The TICT state of LA17b in ethanol is highly emissive with a long fluorescence lifetime: 1.1 ns. TICT state was shown to play an important role in enhancement of intersystem crossing rate. TD-DFT calculations confirm the pathways of relaxation of locally excited state via TICT and triplet states. In films, the photodynamic properties are similar to that of LA17b in hexane and the TICT state vanishes due to the rigid environment. The obtained optical properties of this molecule suggest that it can be a promising candidate for various optoelectronic applications.

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Singlet fission from upper excited singlet states and polaron formation in rubrene film

Abstract: Femtosecond fluorescence up-conversion and transient absorption pump-probe setups are applied to study the relaxation dynamics of the lower and upper excited singlet electronic states in easy-to-make rubrene films.

Cited by 17 publications

References 71 publications

Ultrafast Triplet Generation at the Lead Halide Perovskite/Rubrene Interface

Ultrafast Triplet Generation at the Lead Halide Perovskite/Rubrene Interface

Enhancement of Singlet Fission Yield by Hindering Excimer Formation in Perylene Film

Switching Pathways of Triplet State Formation by Twisted Intramolecular Charge Transfer

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