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  • 1. Farré, Yoann
    et al.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pellegrin, Yann
    Planchat, Aurelien
    Blart, Errol
    Boujtita, Mohammed
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jacquemin, Denis
    Odobel, Fabrice
    Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 15, s. 7923-7940Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 2. Gennari, Marcello
    et al.
    Legalite, Florent
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pellegrin, Yann
    Blart, Errol
    Fortage, Jerome
    Brown, Allison M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Deronzier, Alain
    Collomb, Marie-Noelle
    Boujtita, Mohammed
    Jacquemin, Denis
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Odobel, Fabrice
    Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes2014Inngår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, nr 13, s. 2254-2258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three new cyclometalated iridium complexes were prepared and investigated on nanocrystalline NiO cathodes. Nanosecond transient absorption spectroscopy experiments show they present a surprisingly slow geminate charge recombination upon excitation on NiO, representing thus the first examples of simple sensitizers with such feature. These complexes were used in dye-sensitized solar cells using nanocrystalline NiO film as semiconductor. The long-lived charge separated state of these Ir complexes make them compatible with other redox mediators than I-3(-)/I-, such as a cobalt electrolyte and enable to reach significantly high open circuit voltage.

  • 3.
    Hammarström, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Brown, Allison
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    d'Amario, Luca
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Föhlinger, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Maji, Somnath
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Pullen, Sonja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Dye-sensitized NiO as p-type photocathode for photovoltaic and solar fuels devices2014Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, artikkel-id 77-ENVRArtikkel i tidsskrift (Annet vitenskapelig)
  • 4.
    Hao, Yan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Yang, Wenxing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jiang, Roger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Mijangos, Edgar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Saygili, Yasemin
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells2016Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, artikkel-id 13934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy-by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte-to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system.

  • 5.
    Pati, Palas Baran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Damas, Giane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Tian, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Fernandes, Daniel L. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Bayrak Pehlivan, Ilknur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Araujo, Carlos Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    An experimental and theoretical study of an efficient polymer nano-photocatalyst for hydrogen evolution2017Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 10, nr 6, s. 1372-1376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we report a highly efficient organic polymer nano-photocatalyst for light driven proton reduction. The system renders an initial rate of hydrogen evolution up to 50 +/- 0.5 mmol g(-1) h(-1), which is the fastest rate among all other reported organic photocatalysts. We also experimentally and theoretically prove that the nitrogen centre of the benzothiadiazole unit plays a crucial role in the photocatalysis and that the Pdots structure holds a close to ideal geometry to enhance the photocatalysis.

  • 6.
    Pati, Palas Baran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Fernández-Terán, Ricardo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ahmadi, Sareh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Tian, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 11, s. 2480-2495Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A covalently-linked organic dye-cobaloxime catalyst system is developed by facile click reaction for mechanistic studies and application in a dye sensitized solar fuel device based on mesoporous NiO. This system has been systematically investigated by photophysical measurements, density functional theory, time resolved fluorescence, transient absorption spectroscopy as well as photoelectron spectroscopy. The results show that irradiation of the dye-catalyst on NiO leads to ultrafast hole injection into NiO from the excited dye, followed by a fast electron transfer to reduce the catalyst unit. Moreover, they suggest that the dye undergoes structural changes in the excited state and that excitation energy transfer occurs between neighboring molecules. The photoelectrochemical experiments also show the hydrogen production by this system-based NiO photocathode. The axial chloride ligands of the catalyst are released during photocatalysis to create the active sites for proton reduction. A working mechanism of the dye-catalyst on photocathode is eventually proposed on the basis of this study.

  • 7. Sheibani, Esmaeil
    et al.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Liu, Peng
    Xu, Bo
    Mijangos, Edgar
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Kloo, Lars
    Tian, Haining
    A study of oligothiophene–acceptor dyes in p-type dye-sensitized solar cells2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 22, s. 18165-18177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new dyes, E1 and E2, equipped with triphenylamine as the electron donor, oligothiophene as the linkerand different electron acceptor groups, have been designed and synthesized as photosensitizers for p-typedye-sensitized solar cells (p-DSCs). A systematic study of the effect of molecular structures on the observedphotophysical properties, the electron/hole recombination process, the overall performance and theinterfacial charge separation was carried out. Transient absorption spectroscopy (TAS) shows that the E1dye with a napthoilene-1,2-benzimidazole (NBI) unit as the acceptor has a longer lifetime in the reducedstate than the E2 dye with a malononitrile subunit on the NiO surface.

  • 8. Warnan, Julien
    et al.
    Pellegrin, Yann
    Blart, Errol
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Brown, Allison
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jacquemin, Denis
    Odobel, Fabrice
    Acetylacetone anchoring group for NiO-based dye-sensitized solar cell2014Inngår i: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 105, s. 174-179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, the viability of the first push pull (nitrophenyl and hexyl-thiophene as acceptor and donor unit respectively) sensitizer functionalized with acetylacetone (acac) anchoring group was assessed for application in p-type dye sensitized solar cells (Ni0-based). An effective synthetic strategy to introduce the acac directly to an aryl moiety was developed. Then, the UV visible absorption, emission and electrochemical properties of this new sensitizer were determined. FT-IR spectroscopy revealed an effective binding of the acac group to NiO surface while time-dependent density functional theory (TDDFT) calculations predicted a strong charge-transfer transition with no component of the LUMO centred on the acac. Ultrafast hole injection (<200 fs) from the dye excited state into the valence band (VB) of NiO was experimentally demonstrated by transient absorption spectroscopy studies. It was also shown that excitation of the sensitizer leads to the formation of a twisted intramolecular charge transfer (TICT) state. Finally, the photovoltaic performances of this dye were investigated in NiO based solar cells using the iodide/triiodide electrolyte. We measured promising power conversion efficiencies higher than that of the coumarin 043 benchmark reference albeit with a weaker light harvesting efficiency.

  • 9.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Exploring Electron Transfer Dynamics of Novel Dye Sensitized Photocathodes: Towards Solar Cells and Solar Fuels2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The design of dyes for NiO-based dye-sensitized solar cells (DSSCs) has drawn attention owing to their potential applications in photocatalysis and because they are indispensable for the development of tandem dye-sensitized solar cells. The understanding of the electron transfer mechanisms and dynamics is beneficial to guide further dye design and further improve the performance of photocathode in solar cells and solar fuel devices.

    Time-resolved spectroscopy techniques, especially femtosecond and nanosecond transient absorption spectroscopy, supply sufficient resolution to get insights into the charge transfer processes in p-type dye sensitized solar cell and solar fuel devices. In paper I-V, several kinds of novel organic “push-pull” and inorganic charge transfer dyes for sensitization of p-type NiO, were systematically investigated by time-resolved spectroscopy, and photo-induced charge transfer dynamics of the organic/inorganic dyes were summarized. The excited state and reduced state intermediates were investigated in solution phase as references to confirm the charge injection and recombination on the NiO surface. The charge recombination kinetics is remarkably heterogeneous in some cases occurring on time scales spanning at least six orders of magnitude even for the same dye.

    In this thesis, we also proposed a novel concept of solid state p-type dye sensitized solar cells (p-ssDSSCs) for the first time (paper VI), using an organic dye P1 as sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as electron conductor. Femtosecond and nanosecond transient absorption spectroscopy gave evidence for sub-ps hole injection from excited P1 to NiO, followed by electron transfer from P1●- to PCBM. The p-ssDSSCs device showed an impressive 620 mV open circuit photovoltage.

    Chapter 6 (paper VII) covers the study of electron transfer mechanisms in a covalently linked dye-catalyst (PB-2) sensitized NiO photocathode, towards hydrogen producing solar fuel devices. Hole injection from excited dye (PB-2*) into NiO VB takes place on dual time scales, and the reduced PB-2 (PB-2●-) formed then donates an electron to the catalyst unit.  The subsequent regeneration efficiency of PB-2 by the catalyst unit (the efficiency of catalyst reduction) is determined to ca. 70%.

    Delarbeid
    1. Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells
    Åpne denne publikasjonen i ny fane eller vindu >>Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells
    Vise andre…
    2016 (engelsk)Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, s. 18515-18527Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    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.

    Emneord
    Ultrafast, pDSSCs, Charge recombination
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-300147 (URN)10.1039/c6cp01762b (DOI)000379486200081 ()27338174 (PubMedID)
    Forskningsfinansiär
    Swedish Energy AgencyKnut and Alice Wallenberg Foundation
    Tilgjengelig fra: 2016-08-03 Laget: 2016-08-03 Sist oppdatert: 2017-11-28bibliografisk kontrollert
    2. Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells
    Åpne denne publikasjonen i ny fane eller vindu >>Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells
    Vise andre…
    2016 (engelsk)Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 15, s. 7923-7940Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-280841 (URN)10.1021/acs.jpcc.5b12489 (DOI)000374811100004 ()
    Forskningsfinansiär
    EU, European Research Council, Marches -278845Knut and Alice Wallenberg FoundationSwedish Energy AgencySwedish Research Council
    Tilgjengelig fra: 2016-03-15 Laget: 2016-03-15 Sist oppdatert: 2017-11-30bibliografisk kontrollert
    3. A study of oligothiophene–acceptor dyes in p-type dye-sensitized solar cells
    Åpne denne publikasjonen i ny fane eller vindu >>A study of oligothiophene–acceptor dyes in p-type dye-sensitized solar cells
    Vise andre…
    2016 (engelsk)Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 22, s. 18165-18177Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Two new dyes, E1 and E2, equipped with triphenylamine as the electron donor, oligothiophene as the linkerand different electron acceptor groups, have been designed and synthesized as photosensitizers for p-typedye-sensitized solar cells (p-DSCs). A systematic study of the effect of molecular structures on the observedphotophysical properties, the electron/hole recombination process, the overall performance and theinterfacial charge separation was carried out. Transient absorption spectroscopy (TAS) shows that the E1dye with a napthoilene-1,2-benzimidazole (NBI) unit as the acceptor has a longer lifetime in the reducedstate than the E2 dye with a malononitrile subunit on the NiO surface.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-280839 (URN)10.1039/c5ra26310g (DOI)000370717900043 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg FoundationÅForsk (Ångpanneföreningen's Foundation for Research and Development), 14-452Stiftelsen Olle Engkvist Byggmästare
    Tilgjengelig fra: 2016-03-15 Laget: 2016-03-15 Sist oppdatert: 2017-11-30
    4. Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes
    Åpne denne publikasjonen i ny fane eller vindu >>Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes
    Vise andre…
    2014 (engelsk)Inngår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, nr 13, s. 2254-2258Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Three new cyclometalated iridium complexes were prepared and investigated on nanocrystalline NiO cathodes. Nanosecond transient absorption spectroscopy experiments show they present a surprisingly slow geminate charge recombination upon excitation on NiO, representing thus the first examples of simple sensitizers with such feature. These complexes were used in dye-sensitized solar cells using nanocrystalline NiO film as semiconductor. The long-lived charge separated state of these Ir complexes make them compatible with other redox mediators than I-3(-)/I-, such as a cobalt electrolyte and enable to reach significantly high open circuit voltage.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-230103 (URN)10.1021/jz5009714 (DOI)000338693200015 ()
    Tilgjengelig fra: 2014-09-01 Laget: 2014-08-19 Sist oppdatert: 2017-12-05
    5. Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells
    Åpne denne publikasjonen i ny fane eller vindu >>Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells
    Vise andre…
    2016 (engelsk)Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 81, s. 77184-77194Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    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.

    Emneord
    porphyrins, electron transfer dynamics, NiO
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot kemisk fysik
    Identifikatorer
    urn:nbn:se:uu:diva-301387 (URN)10.1039/c6ra15195g (DOI)000382482200011 ()
    Forskningsfinansiär
    EU, European Research Council, Marches-278845Swedish Energy Agency
    Tilgjengelig fra: 2016-08-22 Laget: 2016-08-22 Sist oppdatert: 2017-11-28bibliografisk kontrollert
    6. Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism
    Åpne denne publikasjonen i ny fane eller vindu >>Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism
    2016 (engelsk)Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 7, s. 5080-5085Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Solid state p-type dye-sensitized solar cells (p-ssDSCs) have been proposed and fabricated for the first time, using the organic dye P1 as the sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as the electron conductor. The p-ssDSC has shown an impressive open circuit photovoltage of 620 mV. Femtosecond and nanosecond transient absorption spectroscopy has given evidence for sub-ps hole injection from the excited P1 to NiO, followed by electron transfer from P1˙ to PCBM.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-280843 (URN)10.1039/C5CP05247E (DOI)000370421500001 ()
    Forskningsfinansiär
    Knut and Alice Wallenberg FoundationSwedish Energy Agency
    Tilgjengelig fra: 2016-03-15 Laget: 2016-03-15 Sist oppdatert: 2017-11-30bibliografisk kontrollert
    7. Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices
    Åpne denne publikasjonen i ny fane eller vindu >>Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices
    Vise andre…
    2017 (engelsk)Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 11, s. 2480-2495Artikkel i tidsskrift (Fagfellevurdert) [Kunstnerisk arbeiden] Published
    Abstract [en]

    A covalently-linked organic dye-cobaloxime catalyst system is developed by facile click reaction for mechanistic studies and application in a dye sensitized solar fuel device based on mesoporous NiO. This system has been systematically investigated by photophysical measurements, density functional theory, time resolved fluorescence, transient absorption spectroscopy as well as photoelectron spectroscopy. The results show that irradiation of the dye-catalyst on NiO leads to ultrafast hole injection into NiO from the excited dye, followed by a fast electron transfer to reduce the catalyst unit. Moreover, they suggest that the dye undergoes structural changes in the excited state and that excitation energy transfer occurs between neighboring molecules. The photoelectrochemical experiments also show the hydrogen production by this system-based NiO photocathode. The axial chloride ligands of the catalyst are released during photocatalysis to create the active sites for proton reduction. A working mechanism of the dye-catalyst on photocathode is eventually proposed on the basis of this study.

    Emneord
    DSSFDs, electron transfer, Cobaloxime catalyst
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot kemisk fysik
    Identifikatorer
    urn:nbn:se:uu:diva-301412 (URN)10.1002/cssc.201700285 (DOI)000403005900021 ()
    Tilgjengelig fra: 2016-08-23 Laget: 2016-08-23 Sist oppdatert: 2017-12-28bibliografisk kontrollert
  • 10.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism2016Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 7, s. 5080-5085Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid state p-type dye-sensitized solar cells (p-ssDSCs) have been proposed and fabricated for the first time, using the organic dye P1 as the sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as the electron conductor. The p-ssDSC has shown an impressive open circuit photovoltage of 620 mV. Femtosecond and nanosecond transient absorption spectroscopy has given evidence for sub-ps hole injection from the excited P1 to NiO, followed by electron transfer from P1˙ to PCBM.

  • 11.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Favereau, Ludovic
    Université de Nantes, France.
    Farre, Yoann
    Université de Nantes, France.
    Maufroy, Antoine
    Université de Nantes, France.
    Pellegrin, Yann
    Université de Nantes, France.
    Blart, Errol
    Université de Nantes, France.
    Hissler, Muriel
    Inst Sci Chim Rennes, France.
    Jacquemin, Denis
    Université de Nantes; Institut Universitaire de France.
    Odobel, Fabrice
    Université de Nantes, France.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 81, s. 77184-77194Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 12.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Favereau, Ludovic
    Farre, Yoann
    Mijangos, Edgar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pellegrin, Yann
    Blart, Errol
    Odobel, Fabrice
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells2016Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, s. 18515-18527Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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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