The Experts below are selected from a list of 36021 Experts worldwide ranked by ideXlab platform

Anders Hagfeldt - One of the best experts on this subject based on the ideXlab platform.

Licheng Sun - One of the best experts on this subject based on the ideXlab platform.

Michael Gratzel - One of the best experts on this subject based on the ideXlab platform.

  • high conversion efficiency Organic Dye sensitized solar cells molecular engineering on d a π a featured Organic indoline Dyes
    Energy and Environmental Science, 2012
    Co-Authors: Yongzhen Wu, Magdalena Marszalek, Shaik M Zakeeruddin, Qiong Zhang, He Tian, Michael Gratzel
    Abstract:

    This paper reports a new D–A–π-A Organic Dye WS-9, which is derived from the known Dye WS-2 by incorporating an n-hexylthiophene unit into the π-conjugation. Due to the presence of a strong electron-withdrawing benzothiadiazole unit in the π-bridge, the specific D–A–π-A Organic Dyes show more complicated electronic transition absorption bands than traditional D–π-A Dyes. The origins of the absorption bands in D–A–π-A Organic Dyes are analysed by density functional theory (DFT). The calculated results in combination with the deprotonation experiments suggest that the spectral response range of D–A–π-A Organic Dyes is superior to that of D–π-A ones. When employed in Dye-sensitized solar cells (DSSCs), the two Dyes show a large difference in aggregation behaviour. It was found that WS-2 forms the unfavourable aggregates more easily. High performance of WS-2 strongly depends on the coadsorbent and suitable Dye bath solvent. In contrast, WS-9 shows strong anti-aggregation ability, and always exhibits high performance regardless of the coadsorbent and Dye bath solvent. Transient photovoltage and photocurrent decay experiments as well as electrochemical impedance spectroscopy indicate that the injected electron lifetime and charge recombination resistance are largely increased due to the introduction of a hexylthiophene unit, resulting in the high photovoltage based on WS-9. The optimized power conversion efficiency of WS-9 reaches 9.04% with high photocurrent (18.00 mA cm−2) and photovoltage (696 mV). The accelerating Dye photo-stability was tested upon light irradiation of a Dye-adsorbed TiO2 film in the absence of redox electrolyte, and a WS-9-based DSSC device with ionic liquid redox electrolyte. These results suggest that the structural engineering of Organic Dyes is important for highly efficient photovoltaic performance of solar cells, and our research will pave a novel way to design new efficient D–A–π-A Organic Dye sensitizers.

  • high open circuit voltage solid state Dye sensitized solar cells with Organic Dye
    Nano Letters, 2009
    Co-Authors: Peter Chen, Junho Yum, Filippo De Angelis, Edoardo Mosconi, Simona Fantacci, Soojin Moon, Robin Humphry Baker, Md K Nazeeruddin, Michael Gratzel
    Abstract:

    Solid-state Dye-sensitized solar cells were fabricated using an Organic Dye, 2-cyanoacrylic acid-4-(bis-dimethylfluoreneaniline)dithiophene (JK2), which exhibits more than 1 V open-circuit potential (Voc). To scrutinize the origin of high voltage in these cells, transient Voc decay measurements and density functional theroy calculations of the interacting Dye/semiconductor surface were performed. A negative conduction band shift was observed due to the favorable dipolar field exerted by the JK2 sensitizer to the TiO2 surface, at variance with heteroleptic Ru(II)-Dyes for which an opposite dipole effect was found, providing an increased Voc.

  • a light resistant Organic sensitizer for solar cell applications
    Angewandte Chemie, 2008
    Co-Authors: Junho Yum, Anders Hagfeldt, Licheng Sun, Soojin Moon, Daniel P Hagberg, Karl Martin Karlsson, Tannia Marinado, Mohammad Khaja Nazeeruddin, Michael Gratzel
    Abstract:

    (Figure Presented) Finely tuned: A stable Dye-sensitized solar cell that contains a molecularly engineered Organic Dye has been prepared. The efficiency of the cell remains at 90% after 1000 h of ...

  • co sensitization of Organic Dyes for efficient ionic liquid electrolyte based Dye sensitized solar cells
    Langmuir, 2007
    Co-Authors: Daibin Kuang, Pascal Comte, Shaik M Zakeeruddin, Mohammad Khaja Nazeeruddin, Pablo Walter, Frank Nuesch, Sanghoon Kim, Michael Gratzel
    Abstract:

    The co-sensitization of two Organic Dyes (SQ1 and JK2), which are complementary in their spectral responses, shows enhanced photovoltaic performance compared with that of an individual Organic Dye-sensitized solar cell. The power conversion efficiency of the co-sensitized Organic Dye solar cell based on the newly developed binary ionic liquid (solvent-free) electrolyte gives 6.4% under AM 1.5 sunlight at 100 mW/cm2 irradiation, which is higher than that of individual Dye-sensitized solar cells. The incident monochromatic photon-to-current conversion efficiency (IPCE) of the co-sensitized solar cell shows typical absorption peaks at 530 and 650 nm corresponding to the two Dyes and displays a broad spectral response over the entire visible spectrum with IPCE of >40% in the 400−700 nm wavelength domain.

Lars Kloo - One of the best experts on this subject based on the ideXlab platform.

  • a thiolate disulfide ionic liquid electrolyte for Organic Dye sensitized solar cells based on pt free counter electrodes
    Chemical Communications, 2011
    Co-Authors: Haining Tian, Anders Hagfeldt, Lars Kloo, Erik Gabrielsson, Ze Yu
    Abstract:

    The ionic liquid, 1-ethyl-3-methylimidazolium tetracyanoborate, was employed to prepare a thiolate/disulfide ionic liquid electrolyte with low viscosity for Organic Dye-sensitized solar cells (DSCs). CoS was introduced and showed better photovoltaic performance in DSCs than the ubiquitous platinized FTO CE.

  • Organic redox couples and Organic counter electrode for efficient Organic Dye sensitized solar cells
    Journal of the American Chemical Society, 2011
    Co-Authors: Haining Tian, Anders Hagfeldt, Lars Kloo, Licheng Sun
    Abstract:

    A series of Organic thiolate/disulfide redox couples have been synthesized and have been studied systematically in Dye-sensitized solar cells (DSCs) on the basis of an Organic Dye (TH305). Photophysical, photoelectrochemical, and photovoltaic measurements were performed in order to get insights into the effects of different redox couples on the performance of DSCs. The polymeric, Organic poly(3,4-ethylenedioxythiophene) (PEDOT) material has also been introduced as counter electrode in this kind of noniodine-containing DSCs showing a promising conversion efficiency of 6.0% under AM 1.5G, 100 mW·cm–2 light illumination. Detailed studies using electrochemical impedance spectroscopy and linear-sweep voltammetry reveal that the reduction of disulfide species is more efficient on the PEDOT counter electrode surface than on the commonly used platinized conducting glass electrode. Both pure and solvated ionic-liquid electrolytes based on a thiolate anion have been studied in the DSCs. The pure and solvated ionic-...

Gerrit Boschloo - One of the best experts on this subject based on the ideXlab platform.