Advances in Liquid‐Electrolyte and Solid‐State Dye‐Sensitized Solar Cells

Snaith, Henry J.; Schmidt‐Mende, Lukas

doi:10.1002/adma.200602903

Cited by 595 publications

(478 citation statements)

References 130 publications

(151 reference statements)

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“…[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.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2010

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“…We should also remark that DSC can be made also with organic electronic hole conductors filling the voids of the porous network, and the interfacial charge transfer implies electron-hole recombination. 46 In Secs. III A-III C we derive first the theory of impedance for diffusion trapping in spatially restricted conditions and, thereafter, the model for recombination coupled with trapping.…”

Section: Device Modelingmentioning

confidence: 99%

Beyond the quasistatic approximation: Impedance and capacitance of an exponential distribution of traps

Bisquert

2008

Phys. Rev. B

132

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Electronic carriers in disordered organic and inorganic semiconductor materials, used in electronic, optoelectronic, and photovoltaic devices, are usually affected by an exponential distribution of localized states in the band gap ͑traps͒. In this paper we provide a full solution of the relaxation of carriers in traps of such distribution, as a function of frequency and steady-state Fermi level. This includes in a unified treatment both the quasistatic limit, in which the traps modify time constants such as the trap-limited mobility, and the power-law relaxation at high frequency due to detrapping kinetics. We also analyze the combination of trapping with diffusion transport and recombination dynamics in photovoltaic devices. The different features of impedance and capacitance spectra are interpreted and also the analysis of the spectra in order to derive the main material parameters.

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“…[24][25][26][27][28] The latter is a great advantage in new generation solid state DSCs where the recombination rate is higher and pore filling can be problematic. 29,30 Even though some of these constructs suffer from a significantly lower surface area and, thus, reduced light harvesting, they do offer a direct charge extraction pathway which results in higher electron lifetime and a lower recombination rate. 31,32 Here, we present a material assembly route for a double layer DSC, integrating a high surface mesoporous underlayer with an optically active 3D photonic crystal (PC) overlayer.…”

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confidence: 99%

Dye-Sensitized Solar Cell Based on a Three-Dimensional Photonic Crystal

et al. 2010

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We present a material assembly route for the manufacture of dye-sensitized solar cells, coupling a high-surface mesoporous layer to a three-dimensional photonic crystal (PC). Material synthesis aided by self-assembly on two length scales provided electrical and pore connectivity at the mesoporous and the microporous level. This construct allows effective dye sensitization, electrolyte infiltration, and charge collection from both the mesoporous and the PC layers, opening up additional parameter space for effective light management by harvesting PC-induced resonances.KEYWORDS Photonic crystal, self-assembly, photovoltaics, dye-sensitized solar cell E ver since the pioneering work of O'Regan and Grät-zel, dye-sensitized solar cells (DSCs) have attracted great interest as a promising technology for future sustainable energy generation. 1 In DSCs, charge carrier generation takes place in a chemisorbed monolayer of photoactive dye which is sandwiched between a semiconductor oxide, usually mesoscopic anatase, and an electrolyte acting as electron and hole conducting materials, respectively. Using state-of-the-art ruthenium-based inorganic dyes, efficiencies higher than 11% have been reported. [2][3][4] DSCs are generally made from cheap and nontoxic components and can be designed in a variety of different colors and transparencies, which distinguishes them as an ideal photovoltaic concept for integrated architecture. It therefore seems only a matter of time before large scale production will follow. 5 In general, improvements in the overall power conversion efficiency have been centered on increasing the photovoltage through manipulation of the oxide, improving the photocurrent with new dyes, and increasing stability by better encapsulation. 5 While record-holding liquid electrolyte DSCs already achieve maximum quantum efficiency (photon-toelectron conversion) in the spectral range around 520 nm, light harvesting in the red and near-infrared (at the tail of the absorption spectra) is still relatively low. In solid-state devices, light absorption is generally limited by the film thickness, as thick mesoporous films prove difficult to infiltrate. 6 One way to successfully enhance light harvesting is the introduction of optical elements, such as highly scattering layers. These consist of large particles, that increase the photon path length in the cell. 7,8 This ubiquitous approach has the unfortunate effect of rendering the DSC opaque thus depriving it of one of its main advantages over competing technologies. As a result, photonic band gap materials in the form of 3D inverted TiO 2 opal or porous bragg stacks have been applied to DSCs to enhance light harvesting in specific partsofthespectrumwhileretainingthecelltransparency. 9-12 Several theoretical approaches report a variety of possible effects, including the localization of heavy photons near the edges of a photonic bandgap, 13 Bragg diffraction in a periodic lattice, 14 multiple scattering at disordered regions in the photonic crystal (PC), 15 and the for...

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Advances in Liquid‐Electrolyte and Solid‐State Dye‐Sensitized Solar Cells

Cited by 595 publications

References 130 publications

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

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

Beyond the quasistatic approximation: Impedance and capacitance of an exponential distribution of traps

Dye-Sensitized Solar Cell Based on a Three-Dimensional Photonic Crystal

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