A Dyadic Sensitizer for Dye Solar Cells with High Energy‐Transfer Efficiency in the Device

Siegers, Conrad; Hohl‐Ebinger, Jochen; Zimmermann, Boris; Würfel, Uli; Mülhaupt, Rolf; Hinsch, Andreas; Haag, Rainer

doi:10.1002/cphc.200700170

Cited by 75 publications

(65 citation statements)

References 53 publications

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“…16 One of the studies was able to demonstrate high excitation transfer efficiency (>89%) between attached dye molecules and an improvement in the device external quantum efficiency of 5-10% between the 400 and 500 nm spectral range. However, the overall power conversion efficiency enhancement of the DSSC was low (<9%), and was argued to arise due to an increase in the open circuit voltage rather than an increase in the short-circuit photocurrent density.…”

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confidence: 99%

Role of Resonance Energy Transfer in Light Harvesting of Zinc Oxide-Based Dye-Sensitized Solar Cells

et al. 2010

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In this contribution we have studied the dynamics of light harvesting of ZnO nanoparticles (NPs) to a surface adsorbed sensitizing dye (SD) N719. By using the picosecond resolved Förster resonance energy transfer (FRET) technique we have explored that the excited ZnO NPs resonantly transfer visible optical radiation to the SD N719. The consequence of the energy transfer on the performance of the overall efficiency of a model ZnO NP-based dye-sensitized solar cell (DSSC) has also been explored. We have demonstrated that the overall efficiency of a ZnO NP-based solar cell significantly depends on the presence of high-energy photons in the solar radiation. In a control experiment on a model TiO 2 NP-based solar cell it has been demonstrated that the presence of high-energy photon has a minimal effect on the performance of the cell as the TiO 2 NPs are incapable of harvesting high-energy photons from solar radiation. The possibility of the back electron transfer from the excited NPs to the SD has also been investigated by studying the NPs in the presence of an ideal electron accepting organic molecule, benzoquinone (BQ). The time constants and nonradiative rate constant obtained for the ZnO/N719 system are found to be different from those of the ZnO/BQ system, which rules out the possibility of back electron transfer from ZnO NPs to SD N719. Moreover, the observed FRET dynamics in the light harvesting process of the nanocrystalites may be efficient in the further use of the nanoparticles in the development of new photodevices.

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Section: -1mentioning

confidence: 99%

Role of Resonance Energy Transfer in Light Harvesting of Zinc Oxide-Based Dye-Sensitized Solar Cells

et al. 2010

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“…Energy relay dyes (ERDs) have been used previously to increase light harvesting in the blue portion of the solar spectrum. 18,19 Blue ERDs, which absorb high energy photons and undergo FRET to sensitizing dyes, can efficiently transfer energy when placed inside the electrolyte 18,20 or cosensitized 21 on nanocrystalline TiO 2 . Grimes et al recently demonstrated that ERDs unattached to the titania and slightly red-shifted relative to the sensitizing dye peak absorption were able to undergo FRET to the SD.…”

Section: Introductionmentioning

confidence: 99%

“…22 However, the low FRET radii (e.g., 1À4 nm) due to the poor overlap between ERD emission and SD absorption prevents efficient energy transfer from occurring when ERDs are placed inside the electrolyte. 23 For DSC systems where energy transfer is weak (i.e., FRET radii <4 nm), NIR-ERDs should be within the FRET radius of the SD to efficiently transfer energy, which requires tethering between dyes 19 or cosensitization on the TiO 2 surface. 21 …”

Section: Introductionmentioning

confidence: 99%

Energy and Hole Transfer between Dyes Attached to Titania in Cosensitized Dye-Sensitized Solar Cells

et al. 2011

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INTRODUCTIONDye-sensitized solar cells comprised mainly of abundant, nontoxic materials offer an inexpensive route to develop highly efficient photovoltaic cells. 1À4 Currently, the most efficient sensitizing dyes are ruthenium-based, metal ligand complexes (e.g., C106 and N719), 5,6 which absorb light in the visible portion of the solar spectrum, have excellent charge injection properties, and produce a high open-circuit voltage, V oc , which is defined as greater than 750 mV. It should be possible to further increase the power conversion efficiency of DSCs by harvesting light in the near-infrared red portion of the spectrum. Cosensitization of titania by dyes with complementary absorption spectra has been demonstrated to broaden the spectral response of organic dye-based DSCs in the visible portion of the spectrum, but not beyond 720 nm. 7À10 Designing near-infrared sensitizing dyes with high internal quantum efficiencies is challenging because reducing the band gap requires more precise alignment of the LUMO and HOMO levels and short conjugated ligands to facilitate charge transfer. To date, only two NIR sensitizing dyes (i.e., peak absorption >700 nm) have demonstrated good charge injection efficiencies in DSCs, but neither dye has a V oc greater than 450 mV. 11,12 Recombination from the electrons in titania with holes in the dye and triiodide in the electrolyte plays a key role in determining the open-circuit voltage. 13 Organic dyes typically experience higher recombination rates resulting in a lower V oc . 14 The great challenge of designing a cosensitized DSC

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“…L ong range energy transfer has recently been used to increase light harvesting [1][2][3][4][5][6][7] inside of dye-sensitized solar cells (DSCs). [8][9][10][11] In one architecture, energy relay dyes (ERDs) absorb high-energy photons and transfer energy via Förster resonant energy transfer to the sensitizing dyes.…”

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confidence: 99%

High Excitation Transfer Efficiency from Energy Relay Dyes in Dye-Sensitized Solar Cells

et al. 2010

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The energy relay dye, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), was used with a nearinfrared sensitizing dye, TT1, to increase the overall power conversion efficiency of a dye-sensitized solar cell (DSC) from 3.5% to 4.5%. The unattached DCM dyes exhibit an average excitation transfer efficiency (ĒTE) of 96% inside TT1-covered, mesostructured TiO 2 films. Further performance increases were limited by the solubility of DCM in an acetonitrile based electrolyte. This demonstration shows that energy relay dyes can be efficiently implemented in optimized dye-sensitized solar cells, but also highlights the need to design highly soluble energy relay dyes with high molar extinction coefficients.KEYWORDS Solar cell, energy transfer, dye-sensitized dolar cell, energy relay dye, titania L ong range energy transfer has recently been used to increase light harvesting 1-7 inside of dye-sensitized solar cells (DSCs). [8][9][10][11] In one architecture, energy relay dyes (ERDs) absorb high-energy photons and transfer energy via Förster resonant energy transfer to the sensitizing dyes. [3][4][5]12 ERDs can both increase and broaden light absorption for the same film thickness in DSCs by increasing the overall dye loading. Because ERDs have a fundamentally different function and design rules than the sensitizing dyes, this architecture greatly expands the range of dyes that can be used in DSCs. In order for energy relay dyes (ERDs) to be used in state-of-the-art dye-sensitized solar cells, the excited ERDs must be able to efficiently transfer energy to the sensitizing dyes. Conventional DSCs are already efficient at absorbing visible light and collecting charges and can achieve external quantum efficiencies (EQE) of 85% at peak absorption. 13 The EQE contribution from the sensitizing dye is determined by the fraction of light absorbed by the sensitizing dye and the internal quantum efficiency (IQE). DSCs have high internal quantum efficiencies (>90%) [14][15][16] and in portions of the visible spectrum can absorb >90% of the light.When photons are absorbed by the energy relay dye in ERD DSCs, they must undergo an additional energy transfer step before contributing to photocurrent; the EQE contribution from the relay dye (EQE ERD ) is thus defined by eq 1, where η ABS,ERD is the fraction of light absorbed by the ERD inside of the titania film and ETE is the average excitation transfer efficiency, or the average probability that an excited relay dye transfers its energy to a sensitizing dye. In order for ERDs to be viable in DSCs, excitation transfer efficiencies of over 90% are required to achieve a peak EQE of 85%.In our first report, only a minimum bound ETE of 46% could be estimated because of the uncertainty in determining η ABS,ERD due to light scattering caused by large TiO 2 nanoparticles and the inability to accurately measure the concentration of the dye because of rapid evaporation of the chloroform electrolyte during the electrolyte filling process. 4 In this report, the ETE is quan...

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A Dyadic Sensitizer for Dye Solar Cells with High Energy‐Transfer Efficiency in the Device

Cited by 75 publications

References 53 publications

Role of Resonance Energy Transfer in Light Harvesting of Zinc Oxide-Based Dye-Sensitized Solar Cells

Role of Resonance Energy Transfer in Light Harvesting of Zinc Oxide-Based Dye-Sensitized Solar Cells

Energy and Hole Transfer between Dyes Attached to Titania in Cosensitized Dye-Sensitized Solar Cells

High Excitation Transfer Efficiency from Energy Relay Dyes in Dye-Sensitized Solar Cells

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