Dye Solar Cells on ITO-PET Substrate with TiO[sub 2] Recombination Blocking Layers

Miettunen, Kati; Halme, Janne; Vahermaa, Paula; Saukkonen, Tapio; Toivola, Minna; Lund, Peter

doi:10.1149/1.3138129

Cited by 57 publications

(86 citation statements)

References 26 publications

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“…In the case of thermal Pt cells, the high frequency peak corresponds to the charge transfer at the counter electrode and the low frequency peak to the charge transfer at the photoelectrode [12][13][14][15]. Contrary to that in the case of porous carbon electrodes, the response of the charge transfer at the counter electrode is actually at low frequencies, around 1 Hz [9].…”

Section: Electrochemical Performancementioning

confidence: 99%

“…Contrary to that in the case of porous carbon electrodes, the response of the charge transfer at the counter electrode is actually at low frequencies, around 1 Hz [9]. The photoelectrode response is at the same frequencies [12][13][14][15], which causes an overlap of these responses. In other words, the charge transfer resistance Rct at the carbon gel counter electrode and the recombination resistance at the photoelectrode RPE form 8 together the large low frequency semicircle (42 Ωcm 2 ) in Figure 5a.…”

Section: Electrochemical Performancementioning

confidence: 99%

Section: Electrochemical Performancementioning

confidence: 99%

“…That resistance might be caused by the contact resistance between the carbon catalyst layer and ITO-PEN (c.f. resistance between ITO-PEN and TiO2 which typically also appears at high frequencies [14,16]), or alternatively, the carbon gel catalyst layer is formed of a few different materials causing some contact resistance between them.Both the ITO-PEN and FTO-glass had similar sheet resistance (15 Ω/sq). As the cells with the carbon gel counter electrode had almost same series resistance as Pt counter electrode ( Figure 5), this suggests that the carbon gel catalyst layer did not significantly contribute to the sheet resistance.…”

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confidence: 99%

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A carbon gel catalyst layer for the roll-to-roll production of dye solar cells

Miettunen

Toivola

Hashmi

et al. 2011

Carbon

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Carbon gel catalyst layers were used in dye solar cells. These layers were prepared on flexible plastic substrates at low temperatures (130 °C). The carbon gel, demonstrated excellent flexibility which is an important feature for roll-to-roll production and special applications of dye solar cells.The use of these low cost and highly flexible catalyst layers resulted in good photovoltaic performance; only 10 % lower than dye solar cells with rigid glass-based counter electrodes prepared with thermal platinization at ~400 °C temperature. 3 IntroductionNanostructured dye solar cells (DSC) [1] represent a potentially cheap photovoltaics option due to simple manufacturing methods and cheap materials. Traditionally DSC have been prepared on glass substrates equipped with transparent conducting oxide (TCO). Although glass is a good option in terms of performance and stability [2,3], its high cost [4] and preparation limited to batch production motivate to find alternatives. A key issue in the commercialization of the DSC is to use roll-to-roll mass production methods to enable cost-effective solutions. Firstly, flexible substrates such as plastics are needed for roll-to-roll production. Secondly, flexibility of the electrode on top of the substrate is required. For instance Miyasaka et al. have demonstrated flexible photoelectrodes that give good cell efficiency (5.8 %) [5].In this work the focus is on counter electrodes. The main task of a counter electrode is to efficiently return the charge from the counter electrode back to electrolyte. Low charge transfer resistances are reached with Pt catalyst layers which are commonly prepared with a high temperature treatment at 400 °C [6]. To lower the cost, the use of carbon has been introduced [7]. The structures of DSC with Pt and porous carbon catalyst layers are show in Figure 1. To compensate the high charge transfer resistance of carbon, the carbon film is thick, usually around 10-20 μm, in order to have large surface area for the catalyst reaction [7]. To create good bonding between the particles which is needed to get high conductivity in the catalyst film, the layer is normally sintered is heat treated at high temperatures (~450 °C) [7].When flexible plastic substrates are used, low temperature methods (<150 °C) are required. Instead of sintering, low temperature pressing has been employed to get good connection between the particles [8,9]. These low temperature layers have provided low charge transfer resistance 0.5-2Ωcm 2 [9]. There have, however, been problems with the flaking of the catalyst layer and the related 4 poor flexibility [9]. Good flexibility of the counter electrode catalyst layer is, however, essential for roll to roll mass production and also important for special applications.In this work we gelatinize carbon paste and combined it to the previously developed pressing method to produce good adhesion between the particles and achieve sufficient flexibility for roll-toroll production. The inspiration for this work came from our previous stud...

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Section: Electrochemical Performancementioning

confidence: 99%

Section: Electrochemical Performancementioning

confidence: 99%

Section: Electrochemical Performancementioning

confidence: 99%

mentioning

confidence: 99%

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A carbon gel catalyst layer for the roll-to-roll production of dye solar cells

Miettunen

Toivola

Hashmi

et al. 2011

Carbon

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“…This is usually adequate with the exception that at low light intensities current leakage from the substrate to the electrolyte is typically signicant [9,10,11] and therefore needs also to be taken into account. There are also a series of other back reactions, such as recombination via oxidized dye, which importance needs to be evaluated on the basis of the employed materials, but with common dyes such as N719 can be assumed negligible.…”

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confidence: 99%

Two-Dimensional Time-Dependent Numerical Modeling of Edge Effects in Dye Solar Cells

et al. 2011

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A two-dimensional transient model of dye solar cells (DSC) describing the electrochemical reactions in the cell has been prepared. The model includes the relevant components of DSCs: the photoelectrode, the electrolyte, and the counter electrode. The solved variables are potential and the concentrations of the dierent ion species, which can be used to determine e.g. the current-voltage characteristics of the cell. The largest benet of this model is its 2D features which enable the study of lateral inhomogeneity. Using the model, a new phenomenon was described: lateral current density distribution caused by a small dierence in the size between photoelectrode and counter electrode, typical to laboratory test cells, causes tri-iodide to move from the edge region to the active area of the cell. This process takes relatively long time (8 min) and can be important for performance characterization and design of DSCs.

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