Porphyrin-Sensitized Solar Cells with Cobalt (II/III)-Based Redox Electrolyte Exceed 12 Percent Efficiency

Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Lausanne-1015, Switzerland.
Science (Impact Factor: 33.61). 11/2011; 334(6056):629-34. DOI: 10.1126/science.1209688
Source: PubMed


The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report
mesoscopic solar cells that incorporate a Co(II/III)tris(bipyridyl)–based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye
as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide
film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because
the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency
of 12.3% under simulated air mass 1.5 global sunlight.

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Available from: Aravind Kumar Chandiran, Dec 25, 2014
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    • "The I À /I 3 À redox couple is generally used, in DSSCs electrolytes, despite the problems related to the long-term stability (Lee et al., 2010; Yanagida et al., 2009) and the partial absorption of visible light (Hamann, 2012). Iodine-free liquid electrolytes based on cobalt (II)/(III) organic complexes (shuttles) have been applied with efficiencies up to 12.3%, in DSSC sensitized with a porphyrin organic dye (Yella et al., 2011). Another interesting 0038-092X/Ó 2015 Elsevier Ltd. "
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    ABSTRACT: A novel, cheap, reliable water based precursor ink has been used for the large scale production of amorphous cobalt sulfide (CoS) on fluorine doped tin oxide (FTO). The method uses a metal-organic complex of Co(II) and thioglycolic acid (TGA), it is cheap and easy to prepare. The electrodes prepared using our method have been applied in the oxidation/reduction using different redox couples dissolved in liquid electrolytes containing: I-/I3-; ferrocene/ferrocenium; bipyridine [Co(bpy)3]2+/3+ complexes and sodium polysulfide. The composition, morphology and the efficiency of the CoS electrodes have been investigated. The CoS films show a good adherence to the substrate, good transparency and an excellent electrocatalytic efficiency with all of the different redox electrolytes. The electrodes have been used in DSSC devices using the organic dye D5 with efficiencies up to 6.8%.
    Solar Energy 12/2015; 122:87-96. DOI:10.1016/j.solener.2015.08.032 · 3.47 Impact Factor
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    • "In this respect, the well-established hybrid xc functional B3LYP (Becke's three parameter functional and the Lee–Yang–Parr functional) [26] was chosen. The calculated values are reasonable and acceptable while comparing with the experimentally known values [7]. "
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    ABSTRACT: The local electric field formed between dye sensitizers and semiconductor interface is one of key factors to determine the overall performance of dye-sensitized solar cells (DSSCs). Herein, a strategy has been proposed to explore the influence of the local electric field on the functionality of DSSCs of YD2-O-C8 dye via calculating the relevant properties in various electric field strengths. The YD2-O-C8 dye has been systemically studied with density functional theory (DFT) and time-dependent DFT (TD-DFT) for its electronic structure and optical properties in tetrahydrofuran (THF) solution. The absorption spectra are gradually narrowing and blue-shifting while increasing the electric field strength. Two key parameters of the light harvesting efficiency (LHE) and the TiO2 conduction band shift (ΔEcb) have been examined for the YD2-O-C8 sensitized TiO2 system. It is found that it is of great importance to reduce the charge accumulation on the TiO2 film, which lowers the electric field strength and shows the best performance of DSSCs. This study is expected to deepen our understanding of the function of local electric field and the operational principles of the DSSCs for further optimization.
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    • "Dye-sensitized solar cell (DSSC) introduced in 1991 by Graetzel [1] is one of the cheap alternative for solar to power conversion device. With the latest efficiency recorded of 12.3%, there is a prospect for DSSC to become as one of the alternative for future renewable energy resources [2]. The photoactive materials, particularly TiO 2 nanostructure, are one of the main factors that hold the key to a better conversion efficiency. "
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    ABSTRACT: We report the study of the utilization of a new synthesized-photoactive materials of Zn-doped TiO2 nanowall (ZTNW) in a dye-sensitized solar cell (DSSC) and the study of the effect of Zn2+ concentration in the ZTNW on the DSSC performance. ZTNW was prepared directly on the ITO substrate using a liquid phase deposition (LPD) method in an aqueous solution containing TiO2 and Zn precursors. The effect of Zn2+ dopants on the performance of DSSC was studied by preparing the ZTNW with several concentrations of Zn2+, namely from 10.0 to 40.0 mM. It was found that the performance of DSSC with a structure of ITO/ZTNW/N719/Electrolyte/Pt increases with the increasing of Zn2+ concentration and optimum at 24.0 mM. Typical power conversion efficiency as high as 1.98% was obtained from the optimum ZTNW sample. The role of Zn2+ concentration in the device performance will be discussed and examined using electrochemical-impedance spectroscopy method.
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