| 1. |
- Hagfeldt, A., et al.
(författare)
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Dye-Sensitized Photoelectrochemical Cells
- 2013. - 2
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Ingår i: Solar cells. - Amsterdam, London : Elsevier. - 9780123869647 ; , s. 385-441
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Production cost per peak watt of solar electricity produced is critical to various PV technologies and second-generation thin-film solar cells. The dye-sensitized solar cell (DSC), a molecular solar cell technology, has the potential to significantly lower production costs below previous PV technologies. DSC research groups have been established around the world. Integration into different products opens up new commercial opportunities for niche applications with large flexibilities in product shape, colour, and transparency.
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| 2. |
- Hagfeldt, A., et al.
(författare)
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Mesoporous dye-sensitized solar cells
- 2012
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Ingår i: Reference Module in Earth Systems and Environmental Sciences. - : Elsevier. - 9780080878737 ; , s. 481-496
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Photovoltaics, or solar cells, are fast growing both with regards to industrialization and research. Globally, the total PV installation is around 40 GW and an annual growth rate of 45% has been experienced over recent years. In the comparison between different photovoltaic technologies a figure of merit is the production cost per peak watt of solar electricity produced. For so called second generation thin film solar cells production costs down to and even below 1 $/W-1 peak are reported. To be competitive with conventional energy sources for large-scale electricity production new PV technologies need to aim at production costs below 0.5 $/W-1 peak. The dye-sensitized solar cell (DSC) is a molecular solar cell technology which have the potential to achieve production costs below 0.5 $/W-1 peak. DSC is based on molecular and nanometer-scale components. Record cell efficiencies of 12%, promising stability data and means of energy efficient production methods have been accomplished. As selling points for the DSC technology the prospect of low-cost investments and fabrication are key features. DSCs offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. This chapter describes the basic principles of the operation of DSC, the state-of-the-art, the materials development that is currently taking place as well as the potentials for future development.
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| 3. |
- Boschloo, Gerrit, et al.
(författare)
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Photomodulated Voltammetry of Iodide/Triiodide Redox Electrolytes and Its Relevance to Dye-Sensitized Solar Cells
- 2011
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 2:24, s. 3016-3020
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Tidskriftsartikel (refereegranskat)abstract
- Photomodulated voltammetry was used to determine the redox potentials of the diiodide radical (I(2)(-center dot)) in water, acetonitrile, and 3-methoxypropionitrile. Iodide/triiodide redox electrolytes were exposed to modulated blue light, resulting in I(2)(-center dot) generation. Using transparent fluorine-doped tinoxide (FTO) electrodes, two modulated photocurrent waves could be discerned in the voltammogram, from which the formal potentials for oxidation and reduction reactions of the diiodide radical were determined. E(0)'(I(2)(-center dot)/I(-)) was found to be +0.79 and +1.04 V versus NHE in acetonitrile and water, respectively. These values give guidelines for E(0)'(D(+)/D) required for efficient regeneration of dyes used in dye-sensitized solar cells.
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| 4. |
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| 5. |
- Feldt, Sandra M., et al.
(författare)
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Design of Organic Dyes and Cobalt Polypyridine Redox Mediators for High-Efficiency Dye-Sensitized Solar Cells
- 2010
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 132:46, s. 16714-16724
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO2 films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.
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| 6. |
- Gibson, Elizabeth A., et al.
(författare)
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Cobalt Polypyridyl-Based Electrolytes for p-Type Dye-Sensitized Solar Cells
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:19, s. 9772-9779
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Tidskriftsartikel (refereegranskat)abstract
- A series of polypyridyl cobalt complexes with different substituents was applied as redox mediators in p-type dye-sensitized solar cells (p-DSCs), consisting of mesoporous NiO sensitized with a perylenemonoimide naphthalenediimide (PMI-NDI) dyad. The photocurrent and photovoltages of the devices were found to depend on the steric bulk of the redox species rather than their electrochemical potential. Bulky substituents were found to slow the detrimental charge recombination reactions between holes in the NiO semiconductor and the reduced form of the redox couple. The open-circuit potential (V-OC) of each of the devices was superior to the equivalent PMI-NDIsensitized p-DSCs containing the triiodide/iodide redox couple.
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| 7. |
- Gibson, Elizabeth A., et al.
(författare)
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Dye sensitised solar cells with nickel oxide photocathodes prepared via scalable microwave sintering
- 2013
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 15:7, s. 2411-2420
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Tidskriftsartikel (refereegranskat)abstract
- Photoactive NiO electrodes for cathodic dye-sensitised solar cells (p-DSCs) have been prepared with thicknesses ranging between 0.4 and 3.0 mu m by spray-depositing pre-formed NiO nanoparticles on fluorine-doped tin oxide (FTO) coated glass substrates. The larger thicknesses were obtained in sequential sintering steps using a conventional furnace (CS) and a newly developed rapid discharge sintering (RDS) method. The latter procedure is employed for the first time for the preparation of p-DSCs. In particular, RDS represents a scalable procedure that is based on microwave-assisted plasma formation that allows the production in series of mesoporous NiO electrodes with large surface areas for p-type cell photocathodes. RDS possesses the unique feature of transmitting heat from the bulk of the system towards its outer interfaces with controlled confinement of the heating zone. The use of RDS results in a drastic reduction of processing times with respect to other deposition methods that involve heating/calcination steps with associated reduced costs in terms of energy. P1-dye sensitized NiO electrodes obtained via the RDS procedure have been tested in DSC devices and their performances have been analysed and compared with those of cathodic DSCs derived from CS-deposited samples. The largest conversion efficiencies (0.12%) and incident photon-to-current conversion efficiencies, IPCEs (50%), were obtained with sintered NiO electrodes having thicknesses of similar to 1.5-2.0 mu m. In all the devices, the photogenerated holes in NiO live significantly longer (tau(h) similar to 1 s) than have previously been reported for P1-sensitized NiO photocathodes. In addition, P1-sensitised sintered electrodes give rise to relatively high photovoltages (up to 135 mV) when the triiodide-iodide redox couple is used.
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| 8. |
- Gibson, Elizabeth A., et al.
(författare)
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Role of the Triiodide/Iodide Redox Couple in Dye Regeneration in p-Type Dye-Sensitized Solar Cells
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:15, s. 6485-6493
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Tidskriftsartikel (refereegranskat)abstract
- A series of perylene dyes with different optical and electronic properties have been used as photosensitizers in NiO-based p-type dye-sensitized solar cells. A key target is to develop dyes that absorb light in the red to near-infrared region of the solar spectrum in order to match photoanodes optically in tandem devices; however, the photocurrent produced was found to decrease dramatically as the absorption maxima of the dye used was varied from 517 to 565 nm and varied strongly with the electrolyte solvent (acetonitrile, propionitrile, or propylene carbonate). To determine the limitations of the energy properties of the dye molecules and to provide guidelines for future sensitizer design, we have determined the redox potentials of the duodide radical intermediate involved in the charge-transfer reactions in different solvents using photomodulated voltammetry. E degrees(I-3(-)/I-2(center dot-)) (V vs Fe(Cp)(2)(+/0)) = -0.64 for propylene carbonate, -0.82 for acetonitrile, and -0.87 for propionitrile. Inefficient regeneration of the sensitizer appears to be the efficiency-limiting step in the device, and the values presented here will be used to design more efficient dyes, with more cathodic reduction potentials, for photocathodes in tandem dye-sensitized solar cells.
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| 9. |
- Hagfeldt, Anders, et al.
(författare)
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Dye-sensitized Photoelectrochemical Cells
- 2012. - 2
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Ingår i: Practical Handbook of Photovoltaics Findamentals and Applications, 2nd Edition. - Oxford : Academic Press. ; , s. 479-542
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Bokkapitel (refereegranskat)abstract
- As part of the growing sustainable and renewable energy movement, the design, manufacture and use of photovoltaic devices is increasing in pace and frequency. The Handbook of Photovoltaics will be a 'benchmark' publication for those involved in the design, manufacture and use of these devices. The Handbook covers the principles of solar cell function, the raw materials, photovoltaic systems, standards, calibration, testing, economics and case studies. The editors have assembled a cast of internationally-respected contributors from industry and academia. The report is essential reading for: Physicists, electronic engineers, designers of systems, installers, architects, policy-makers relating to photovoltaics.
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| 10. |
- Li, Lin, et al.
(författare)
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Double-Layered NiO Photocathodes for p-Type DSSCs with Record IPCE
- 2010
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 22:15, s. 1759-1762
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Tidskriftsartikel (refereegranskat)abstract
- A way to achieve a high-efficiency dye-sensitized solar cell is to combine an n-type TiO2-based photoanode with a p-type photocathode in a tandem configuration. The development of an efficient photocathode is, at present, the key target. We have optimized the NiO, I-3(-)/I- p-DSSC system to obtain record photocurrent, giving 64% incident photon-to-current conversion efficiency (IPCE) and 5.48 mAcm(-2) J(SC).
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| 11. |
- Odobel, Fabrice, et al.
(författare)
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Recent advances and future directions to optimize the performances of p-type dye-sensitized solar cells
- 2012
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Ingår i: Coordination chemistry reviews. - : Elsevier BV. - 0010-8545 .- 1873-3840. ; 256:21-22, s. 2414-2423
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Forskningsöversikt (refereegranskat)abstract
- This review provides a summary of the most important developments in the field of solar cells based on the sensitization of p-type semiconductors, such as NiO, and identifies the future challenges and opportunities to enhance their overall performance. In particular, the main factors responsible for the low open-circuit voltage, short circuit photocurrent and fill factor are discussed in detail.
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| 12. |
- Preat, Julien, et al.
(författare)
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Investigation of the photoinduced electron injection processes for p-type triphenylamine-sensitized solar cells
- 2011
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 4:11, s. 4537-4549
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Tidskriftsartikel (refereegranskat)abstract
- We have carried out theoretical investigation aiming at modelling the assessment of mechanisms of photoinduced processes in a recent p-type organic metal-free dye derived from the triphenylamine (P-1) structure. In the P-1 system, one uses the triphenylamine moiety as the electron donor, malononitrile as the electron acceptor, and a thiophene that plays the role of the conjugated chain. Basically, the difference between the P-1 dye and the common organic dyes used in the n-type DSSC field is the anchoring group located on the electron donor group. In a first step, DFT and TDDFT approaches have been exploited to calculate the key parameters controlling both the intramolecular charge transfer (ICT) and hole transfer rate constants in the Gurney-Gerischer-Marcus (GGM) formalism, for either a solvent-controlled adiabatic or a nonadiabatic electron transfer. These are: (i) the electronic coupling; (ii) the reorganization energies; and (iii) the variation of the Gibbs energy. The gathered results are in agreement with the experimental trends. (i) The vertical ICT excited states energy has been calculated at 2.67 eV, in perfect line with the experiment (2.65 eV). (ii) Two mechanisms can be conceived for the hole transfer and regeneration process. The first deals with the reduction of dye molecule at the excited state followed by an electron transfer from the reduced dye to the oxidized regenerator. The second implies a redox reaction between the excited dye and the oxidized regenerator, followed by an electron transfer from the cathode to the oxidized dye. (iii) Our theoretical investigation suggests that the first mechanism is dominant. Secondly, we propose structural modifications improving the TPA-based DSSCs hole transfer efficiency and we show that an additional -CN graft on the malononitrile unit combined to the functionalisation of the TPA moieties by -OMe groups (to give P-1b) should significantly improve the key parameters related to the electron injection. Indeed, for P-1b, we have noticed an increase of both the RLHE factor (0.907) and the injection driving force (-0.33 eV). This dye is therefore expected to be a very promising molecule in the p-type DSSC field.
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| 13. |
- Qin, Peng, et al.
(författare)
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Synthesis and Mechanistic Studies of Organic Chromophores with Different Energy Levels for p-Type Dye-Sensitized Solar Cells
- 2010
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:10, s. 4738-4748
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Tidskriftsartikel (refereegranskat)abstract
- A series of donor-pi-acceptor dyes with different electron-withdrawing groups were designed and synthesized for p-type dye-sensitized Solar cells. The modification of dye structures shows significant influence on the photophysical, electrochemical, and photovoltaic performance of the dyes. DSSCs based on these dyes show maximum 63% and minimum 6% of incident monochromatic photon-to-current conversion efficiencies. The two dyes with the highest (P1) and lowest (P3) efficiencies were Studied by femtosecond transient absorption spectroscopy, which shows a fast injection rate of more than (250 fs)(-1) for both dyes. Such fast injection corresponds to more than 90% injection efficiency. The photoinduced absorption Spectroscopy Study of sensitized NiO films in the presence of electrolyte showed poor regeneration of 113 due to all insufficient driving force. This, together with aggregation of the dye on the NiO film, explained the poor solar cell performance.
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| 14. |
- Roy-Mayhew, Joseph D., et al.
(författare)
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Functionalized Graphene Sheets as a Versatile Replacement for Platinum in Dye-Sensitized Solar Cells
- 2012
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 4:5, s. 2794-2800
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Tidskriftsartikel (refereegranskat)abstract
- Several techniques for fabricating functionalized graphene sheet (FGS) electrodes were tested for catalytic performance in dye-sensitized solar cells (DSSCs). By using ethyl cellulose as a sacrificial binder, and partially thermolyzing it, we were able to create electrodes which exhibited lower effective charge transfer resistance (<1 Omega cm(2)) than the thermally decomposed chloroplatinic acid electrodes traditionally used. This performance was achieved not only for the triiodide/iodide redox couple, but also for the two other major redox mediators used in DSSCs, based on cobalt and sulfur complexes, showing the versatility of the electrode. DSSCs using these FGS electrodes had efficiencies (eta) equal to or higher than those using thermally decomposed chloroplatinic acid electrodes in each of the three major redox mediators: I (eta(FGS) = 6.8%, eta(Pt) = 6.8%), Co (4.5%, 4.4%), S (3.5%, 2.0%). Through an analysis of the thermolysis of the binder and composite material, we determined that the high surface area of an electrode, as determined by nitrogen adsorption, is consistent with but not sufficient for high performing electrodes. Two other important considerations are that (i) enough residue remains in the composite to maintain structural stability and prevent restacking of FGSs upon the introduction of the solvent, and (ii) this residue must not disperse in the electrolyte.
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