| 1. |
- Farré, Yoann, et al.
(författare)
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A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO-Based Dye-Sensitized Solar Cells
- 2020
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:7, s. 1844-1855
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Tidskriftsartikel (refereegranskat)abstract
- The anchoring group of a sensitizer may strongly affect the overall properties and stability of the resulting dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthetic solar cells (DSPECs). The properties of seven perylene monoimide (PMI) dyes have been comprehensively studied for their immobilization on nanocrystalline NiO film. The PMI dyes differ only by the nature of the anchoring group, which are: carboxylic acid (PMI-CO2H), phosphonic acid (PMI-PO3H2), acetyl acetone (PMI-acac), pyridine (PMI-Py), aniline (PMI-NH2), hydroxyquinoline (PMI-HQ), and dipicolinic acid (PMI-DPA). The dyes are investigated by cyclic voltammetry and spectroelectrochemistry and modeled by TD-DFT quantum chemical calculations. The mode of binding of these anchoring groups is investigated by infrared spectroscopy and the stability of the binding to NiO surface is studied by desorption experiments in acidic and basic media. The phosphonic acid group is found to offer the strongest binding to the NiO surface in terms of stability and dye loading. Finally, a photophysical study by ultrafast transient absorption spectroscopy shows that all dyes inject a hole in NiO with rate constants on a subpicosecond timescale and display similar charge recombination kinetics. The photovoltaic properties of the dyes show that PMI-HQ and PMI-acac give the highest photovoltaic performances, owing to a lower degree of aggregation on the surface.
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| 2. |
- Farré, Yoann, et al.
(författare)
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Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:15, s. 7923-7940
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Tidskriftsartikel (refereegranskat)abstract
- In this study, four new diketopyrrolopyrrole (DPP) sensitizers, with a dicarboxylated triphenylamine anchoring group for attachment to NiO, were prepared and their electronic absorption, emission and electrochemical properties were recorded. The nature of the electronic excited-states was also modeled with TD-DFT quantum chemistry calculations. The photovoltaic performances of these new dyes were characterized in NiO-based dye-sensitized solar cells (DSCs) with the classical iodide/triiodide and cobaltII/III-polypyridine electrolytes, in which they proved to be quite active. Laser spectroscopy on dye/NiO/electrolyte films gave evidence for ultrafast hole injection into NiO (0.2-10 ps time scales). For the dyes with an appended naphtalenediimide (NDI) acceptor unit, ultrafast electron transfer to the NDI dramatically prolonged the lifetime of the charge separated state NiO(+)/dye-, from the ps time scale to an average lifetime ≈ 0.25 ms, which is among the slowest charge recombinations ever reported for dye/NiO systems. This allowed for efficient regeneration by CoIIIpolypyridine electrolytes, which translated into much improved PV-performance compared to the DPP dyes without appended NDI. Overall, these results underscore the suitability of DPP as sensitizers for NiO-based photoelectrochemical devices for photovoltaic and photocatalysis.
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| 3. |
- Wood, Christopher J., et al.
(författare)
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A comprehensive comparison of dye-sensitized NiO photocathodes for solar energy conversion
- 2016
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 18:16, s. 10727-10738
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Tidskriftsartikel (refereegranskat)abstract
- We investigated a range of different mesoporous NiO electrodes prepared by different research groups and private firms in Europe to determine the parameters which influence good quality photoelectrochemical devices. This benchmarking study aims to solve some of the discrepancies in the literature regarding the performance of p-DSCs due to differences in the quality of the device fabrication. The information obtained will lay the foundation for future photocatalytic systems based on sensitized NiO so that new dyes and catalysts can be tested with a standardized material. The textural and electrochemical properties of the semiconducting material are key to the performance of photocathodes. We found that both commercial and non-commercial NiO gave promising solar cell and water-splitting devices. The NiO samples which had the two highest solar cell efficiency (0.145% and 0.089%) also gave the best overall theoretical H-2 conversion.
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| 4. |
- Zhang, Lei, et al.
(författare)
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Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:81, s. 77184-77194
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Tidskriftsartikel (refereegranskat)abstract
- Porphyrin dyes were synthesized for use in p-type (NiO) dye sensitized solar cells based on different designprinciples. One porphyrin was designed with a significant charge transfer character in the excited statebecause of push–pull effects of the substituents. Another porphyrin had instead an appended NDIacceptor group (NDI ¼ naphthalene diimide). The dyes were characterized by spectroscopic,electrochemical and DFT methods. Solar cells based on sensitized, meso-porous NiO showed ratherpoor performance compared to other organic dyes, but with a clear improvement for the dye with theNDI acceptor. Ultrafast transient absorption spectroscopy and nanosecond laser photolysis showed thathole injection into NiO was followed by unusually rapid charge recombination, predominantly ona 50–100 ps time scale, which is likely the main reason for the poor photovoltaic performance. Againthe porphyrin with the NDI group showed a more long-lived charge separation that should lead to betterdye regeneration in a solar cell, which can explain its better photovoltaic performance.
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| 5. |
- Zhang, Lei, et al.
(författare)
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Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells
- 2016
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 18, s. 18515-18527
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Tidskriftsartikel (refereegranskat)abstract
- In a photophysical study, two diketopyrrolopyrrole (DPP)-based sensitizers functionalized with4-thiophenecarboxylic acid as an anchoring group and a bromo (DPPBr) or dicyanovinyl (DPPCN2)group, and a dyad consisting of a DPP unit linked to a naphthalenediimide group (DPP–NDI), wereinvestigated both in solution and grafted on mesoporous NiO films. Femtosecond transient absorptionmeasurements indicate that ultrafast hole injection occurred predominantly on a timescale of B200 fs,whereas the subsequent charge recombination occurred on a surprisingly wide range of timescales,from tens of ps to tens of ms; this kinetic heterogeneity is much greater than is typically observed fordye-sensitized TiO2 or ZnO. Also, in contrast to what is typically observed for dye-sensitized TiO2, therewas no significant dependence on the excitation power of the recombination kinetics, which can beexplained by the hole density being comparatively higher near the valence band of NiO beforeexcitation. The additional acceptor group in DPP–NDI provided a rapid electron shift and stabilizedcharge separation up to the ms timescale. This enabled efficient (B95%) regeneration of NDI bya CoIII(dtb)3 electrolyte (dtb = 4,40-di-tert-butyl-2,20-bipyridine), according to transient absorptionmeasurements. The regeneration of DPPBr and DPPCN2 by CoIII(dtb)3 was instead inefficient, as mostrecombination for these dyes occurred on the sub-ns timescale. The transient spectroscopy data thuscorroborated the trend of the published photovoltaic properties of dye-sensitized solar cells (DSSCs)based on these dyes on mesoporous NiO, and show the potential of a design strategy with a secondaryacceptor bound to the dye. The study identifies rapid initial recombination between the dye and NiO asthe main obstacle to obtaining high efficiencies in NiO-based DSSCs; these recombination componentsmay be overlooked when studies are conducted using only methods with ns resolution or slower.
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