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

Abstract

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...

Improved Photocurrent of a Poly (3,4-ethylenedioxythiophene)-ClO4–/TiO2 Thin Film-modified Counter Electrode for Dye-sensitized Solar Cells

“…To further elucidate the photocurrent behavior of the DSSC, electrochemical impedance spectroscopy EIS of the electrochemical cells with PEDOT-ClO 4 at a scan rate of 0.1 V s 1 from 0.5 V to 1.5 V using a potentiostat. The electrochemical cell comprised a PEDOTClO 4 /TiO 2 tf /FTO, PEDOT-ClO 4 /FTO, PEDOT-ClO 4 / TiO 2 pf /FTO, or Pt film WE; a Pt film CE prepared by sputter deposition; and an Ag/AgI reference electrode.…”

“…The photocurrent-voltage characteristics indicate that DSSCs with PEDOT-ClO 4 − /TiO 2 thin-film counter electrodes had a high photovoltaic conversion effi ciency similar to that of PEDOT-ClO 4 We evaluated the performance of the TiO 2 tf CE in comparison to a PEDOT-ClO 4 /TiO 2 particle film TiO 2 pf electrode using cyclic voltammetry and electrochemical impedance measurements and by assessing the performance of a solar cell with a transparent PEDOT-ClO 4 /TiO 2 tf electrode. In addition, we investigated the infl uence of refl ected light on the photocurrent using a modifi ed CE.…”

Inkjet-printed graphene electrodes for dye-sensitized solar cells

“…The lower R SH for the graphene CEs could be attributed to factors such as current leakage paths on the graphene based electrodes, while the higher R SE could arise from the lower conductivity (i.e. higher sheet resistance) of the graphene electrode (600 Ω/□) compared to that of the Pt based electrode (15 Ω/□), or to slower electro-kinetics in graphene than in Pt [82,83]. pulcherrima dye based cells (Gr and Pt CEs) could be attributed to a better intermolecular π-π* interactions in the dye arising from these carotenoids.…”

Electrochemical properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and carbon black composite as an electron injector into the electrolyte containing iodide redox couple

“…Also CB powder can be readily dispersed in a solvent so that printing process such as spray coating at low temperature is applicable [12]. Carbon materials form a porous layer with a large surface area between carbon nanostructures but still several tens of micrometers (10 mm to 25 mm) are required for carbon based electrodes to achieve comparable catalytic activity as the Pt electrode because the intrinsic electrocatalytic activity of carbon materials is lower than that of Pt [26]. Then the total internal resistance of the solar cell is increased, resulting in the reduction of fill factor and efficiency [27].…”