Singlet and Triplet Excited-State Dynamics of a Nonfullerene Electron Acceptor Y6

Natsuda, Shin-ichiro; Sakamoto, Yuji; Takeyama, Taiki; Shirouchi, Rei; Saito, Toshiharu; Tamai, Yasukatsu; Ohkita, Hideo

doi:10.1021/acs.jpcc.1c06448

Cited by 39 publications

(93 citation statements)

References 45 publications

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“…This spectral shape is likely due to an overlapping ESA, as TA data taken in Y6 films also show a dip in the bleach around 750 nm. 18,19,26 A weak and broad ESA is also present from 420 nm to 600 nm which at early times is assigned to the initially excited Y6 singlet. Over time, there are some subtle changes in shape of both the 420 nm to 600 nm and ∼750 nm ESA (Supplementary Information, Figure S21).…”

Section: Transient Absorption Spectroscopymentioning

confidence: 98%

“…The spectrum of the neat Y6 thin film is similar to films previously reported in the literature. 17,19,[25][26][27][28][29] In chloroform solutions of Y6, the lowest energy peak (∼815 nm) and its shoulder (∼730 nm)…”

Section: Steady-state Absorption and Emissionmentioning

confidence: 99%

“…The shape changes observed here may be due to the formation of a charge-transfer state in Y6 NPs, but here the shape change continues to progress for at least 200 ps (Supporting Information, Figure S21), which is a significantly longer time-scale than the 0.2 ps reported by Wang et al Additionally, in Y6 films a small residual excited-state population with a long lifetime has been observed previously. 18,19,26 Liang et al attributed this observation to the formation of long-lived triplets through inter-system crossing (ISC). 19 Similarly, Natsuda et al observed long-lived triplets generated through ISC or by singlet-singlet annihilation, where a high-energy singlet state is formed, which subsequently undergoes singlet fission to two triplets.…”

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

“…In the near-infrared, Y6 triplets are characterized by a broad ESA around 1400 nm and an ESA that overlaps the bleach from 750 nm to 800 nm. 26,29 However, like the charge-transfer state, the absorption of Y6 triplets in the <600 nm region is unknown. Triplet formation through singlet-singlet annihilation in these NPs is feasible as we were unable to eliminate power dependence (Supporting Information, Figure S25).…”

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

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Red-Light-Mediated Photocatalytic Hydrogen Evolution by Hole Transfer from Non-Fullerene Acceptor Y6

Kee

Perrelle

Dolan

et al. 2022

Preprint

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One of the highest performing materials in organic photovoltaics is a blend of the polymer donor PM6 and non-fullerene acceptor (NFA) Y6. We report the use of 1:1 PM6:Y6 blend nanoparticles (NPs) prepared by the miniemulsion method for the photocatalytic production of hydrogen under sacrificial conditions, with a 2% mass loading of Pt co-catalyst. When pre- pared using TEBS, a thiophene-containing surfactant, these blend NPs have a desirable inter- mixed morphology. Under ≈1-sun illumination from 400 to 900 nm, hydrogen is produced at a rate of 8000 ± 400 μmol h−1 g−1, which is among the highest reported for organic photocata- lysts under similar conditions. Remarkably, this rate remains high at 5200 ± 300 μmol h−1 g−1 under 650 −900 nm excitation, where Y6 is exclusively excited, generating free charges by hole transfer from Y6 to PM6. The rate drops to 2400 ± 200 μmol h−1 g−1 at 400 −600 nm excitation, where PM6 is preferentially excited and free charges are generated from the conventional electron transfer mechanism. Additionally, external quantum efficiencies of 0.27 ± 0.08% at 405nm, 0.19 ± 0.04% at 565nm, and 0.22 ± 0.02% at 780nm were measured, indicating that this photocatalyst uses a broad region of solar spectrum to yield hydrogen from excitation of both the donor and the acceptor. Transient absorption spectroscopy results show that both hole transfer and electron transfer occur following the excitation of Y6 and PM6, respectively. This work is the first study to show that free charge generation via hole transfer is the dominant mechanism of hydrogen evolution in a donor:NFA blend. This work also highlights the potential that other donor:NFA blends may have for highly efficient green hydrogen production.

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Section: Transient Absorption Spectroscopymentioning

confidence: 98%

Section: Steady-state Absorption and Emissionmentioning

confidence: 99%

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

See 2 more Smart Citations

Red-Light-Mediated Photocatalytic Hydrogen Evolution by Hole Transfer from Non-Fullerene Acceptor Y6

Kee

Perrelle

Dolan

et al. 2022

Preprint

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show abstract

“…7,10,34 This low EQE is likely due to the single-component nature of the NPs, in which there is a lower driving force for charge separation when compared to a donor:acceptor heterojunction. In Y6 films, most excited states are lost within ∼100 ps of excitation,, 24,27,35 indicating that the formation and persistence of free charges may be limited by exciton-exciton and charge recombination in the NP bulk. Y6 NPs have similarly short excited-state lifetimes, which are further discussed later in this article.…”

Section: Photocatalytic Hydrogen Evolutionmentioning

confidence: 99%

Surfactant Effects on Hydrogen Evolution by Small Molecule Non-Fullerene Acceptor Nanoparticles

Dolan

Perrelle

Milsom

et al. 2022

Preprint

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Organic donor:acceptor semiconductor nanoparticles (NPs) formed through the miniemul- sion method have been shown to be active photocatalysts. Here we report photocatalytic hydrogen (H2) evolution under sacrificial conditions with Pt as a co-catalyst by NPs comprising only the non-fullerene acceptor Y6, stabilized by either sodium dodecyl sulfate (SDS) or the thiophene-containing surfactant 2-(3-thienyl)ethyloxybutylsulfonate sodium salt (TEBS). Typically, changes in the photocatalytic activity of donor:acceptor NPs are associated with differences in morphology due to the use of surfactants. However, as these NPs are single-component, their photocatalytic activity has a significantly lower dependence on morphology than two-component donor:acceptor NPs. Results from ultrafast transient absorption spectroscopy show a minor difference between the photophysics of the TEBS- and SDS-stabilized Y6 NPs, with free charges present with either surfactant. The similar photophysics suggest that both TEBS- and SDS-stabilized Y6 NPs would be expected to have similar rates of H2 evolution. However, the results from photocatalysis show that Y6 NPs stabilized by TEBS have a H2 evolution rate 21 times higher than that of the SDS- stabilized NPs under broadband solar-like illumination (400–900 nm). Transmission electron microscopy images of the Y6 NPs show effective photodeposition of Pt on the surface of the TEBS-stabilized NPs. In contrast, photodeposition of Pt is inhibited when SDS is used. Furthermore, the zeta potential of the NPs is higher in magnitude when SDS is present. Hence, we hypothesize that SDS forms a dense, insulating layer on the NP surface which hinders the photodeposition of Pt and reduces the rate of H2 evolution. This insulating effect is absent for TEBS-stabilized Y6 NPs, allowing a high rate of H2 evolution. The TEBS-stabilized Y6 NPs have a H2 evolution rate higher than most single-component organic photocatalysts, signaling the potential use of the Y-series acceptors for H2 evolution in Z-scheme photocatalysis.

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Enhanced Photocatalytic and Photovoltaic Performance Arising from Unconventionally Low Donor–Y6 Ratios

Dolan,

Pan,

Griffith

et al. 2024

Advanced Materials

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Development of both organic photovoltaics (OPVs) and organic photocatalysts has focused on utilizing the bulk heterojunction (BHJ). The BHJ promotes charge separation and enhances the carrier lifetime, but may give rise to increased charge traps, hindering performance. Here, high photocatalytic and photovoltaic performance is displayed by electron donor–acceptor (D–A) nanoparticles (NPs) and films, using the non‐fullerene acceptor Y6 and polymer donor PIDT‐T8BT. In contrast to conventional D–A systems, the charge generation in PIDT‐T8BT:Y6 NPs is mainly driven by Y6, allowing a high performance even at a low D:A mass ratio of 1:50. The high performance at the low mass ratio is attributed to the amorphous behaviour of PIDT‐T8BT. Low ratios have generally been thought to yield lower efficiency than the more conventional ∼1:1 ratio. However, the OPVs exhibit peak performance at a D:A ratio of 1:5. Similarly the NPs used for photocatalytic hydrogen evolution show peak performance at the 1:6.7 D:A ratio. Interestingly, for the PIDT‐T8BT:Y6 system, as the polymer proportion increases, we observe a reduced photocatalytic and photovoltaic performance. The unconventional D:A ratios provide lower recombination losses and increased charge‐carrier lifetime with undisrupted ambipolar charge transport in bulk Y6, enabling better performance than conventional ratios. This work reports novel light‐harvesting materials in which performance is reduced due to unfavourable morphology as D:A ratios move towards conventional ratios of 1:1.2–1:1.This article is protected by copyright. All rights reserved

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Singlet and Triplet Excited-State Dynamics of a Nonfullerene Electron Acceptor Y6

Cited by 39 publications

References 45 publications

Red-Light-Mediated Photocatalytic Hydrogen Evolution by Hole Transfer from Non-Fullerene Acceptor Y6

Red-Light-Mediated Photocatalytic Hydrogen Evolution by Hole Transfer from Non-Fullerene Acceptor Y6

Surfactant Effects on Hydrogen Evolution by Small Molecule Non-Fullerene Acceptor Nanoparticles

Enhanced Photocatalytic and Photovoltaic Performance Arising from Unconventionally Low Donor–Y6 Ratios

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