dye sensitized solar cells presentation
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DESCRIPTIONspecial discussion over a solar cell model
Counter electrodeAtul kumar12307005
Gratzel Cell Photo-electrochemical CellArtificial photosynthesis
Dye-sensitized solar cells: Components Granular TiO2 forming a nanoporous structure.
A dye, which is a light sensitive substance spread on the TiO2 surface.
A redox couple (I-/I3-), located in the space between the dye and the cathode.
Fto coated front glass and counter electrode coated back substrateTiO2Electrolyte
Dye-sensitized solar cells: Operation Dye electrons are excited by solar energy absorption.
They are injected into the conduction band of TiO2.
Get to counter-electrode (cathode) through the external circuit.
: Redox regeneration at the counter-electrode (oxidation).
: Dye regeneration reaction (reduction).
Potential used for external work:Red=I-Ox =I3-Ionic Liquid
Nanocrystalline Solar Cell: MaterialsMaterials:F-SnO2glass slidesIodine and triIodide electrolyteColloidal Titanium Dioxide PowderRuthenium n3 dye.Counter electrode
Counter electrodeThe counter electrode is one of the most important components of dssc, sinceIt has the function of reducing the oxidized mediator species Transferring the electrons from load to electrolyte/Collecting the holes from the hole transporting material. Sufficiently corrosion-resistant to electrolyte. In equivalent circuit of dssc the counter electrode constant phase element, charge transfer resistance of counter electrode.
the choice of the counter electrode depends as platinum is a precious metal
Carbon-based materials, and other platinum-free catalytic layers, deposited over different substrates, such as metal foils and plastic sheets are tried. .
Carbon counter electrode dssc
Method for deposition of counter electrodePt was electrodeposited from a solution containing 10 mM H2PtCl6 and 0.5 M KCl in a three-electrode cell withindium tin oxide (ITO) glass working electrode,Pt mesh auxiliary electrode, Ag/AgCl reference electrode.
Technique used to deposit the pt using Chronopotentiometry
ChronopotentiometryChronopotentiometry (CP) is the most basic constant current experiment where step current is applied across an electrochemical cell.The galvanostat uses a three electrode configuration. The basis of controlled current experiments is that a redox (electron transfer) reaction that must occur at the surface of the working electrode in order to support the applied current applications of this is constant current electrolysis such as electrodeposition
Pt deposition10mM H2PtCl6.6H2o,10mM KCl are taken in 20 ml H2O to from a solution for electrodeposition of Pt .
pt deposition for 600s using chronopotentiometry pt deposition for 300s using chronopotentiometry
Pt deposition for 150s using chronopotentiometry
Counter electrode characterization:CVApplication of a reversing linear sweep
If an electro active species is present we obtain a Faradaic current, summed to the background charging current
I = IC+If
Counter electrodeGood catalytic activity for triiodide to iodide conversionLow resistancePtAuCarbon WO2Nb2O5Cobalt
CVE = (Epa + Epc)/2 DEp = Epa - Epc = 59mV/n
The deposited pt are checked for the catalytic activity by cv in the solution of 10mM LiI, 1mM I, 0.1mM LiClO4 in 25 ml acetonitrile
Counter electrode characterizationCv of pt deposited (600s)Cv of pt deposited (600s)
Cv of aluminium doped zno coated glass substrate
Carbon counter electrode We also prepared carbon counter electrode by depositing carbon on tco glass we prepared two carbon glass plate by depositng carbon for 10 second dark and 2 second light deposit.and took cv for checking catalytic activity of carbon coted counter electrode.
Cv Carbon thick deposition for 10 second Cv Carbon thin deposition for 2 second
Fabrication of dsscProcedure:Add 1 gram of TiO2 (in 1 ml H2O) of a drop of acetic acid (ph3-4) in a mortar and pestle.Grinding for 30 minutes will produce a lump free paste.1 drop of a surfactant is then added (mercapta propanoic acid).
Semiconductor electrodeSupport for dye adsorptionWide bandgap semiconductor High surface areaGood electron conductivityLow recombinationNanoparticlesNanotubesDouble layerZnO
Way towards higher efficiencyBetter light absorberSolid electrolyte Cheaper Counter electrode materialSuitable electrode Simple and cheap TCO materialHigher efficiency to be suitable for production in large scale
Coating the CellAfter testing to determine which side is conductive, one of the glass slides is then masked off 1-2 mm on THREE sides with masking tape. This is to form a mold.A couple of drops if the titanium dioxide suspension is then added and distributed across the area of the mold with a glass rod.The slide is then set aside to dry for one minute.
After the first slide has dried the tape can be removed.The titanium dioxide layer needs to be heat sintered and this can be done by using a hot air gun that can reach a temperature of at least 450 degrees Celsius.This heating process should last 30 minutes.
Dye Absorption and Coating the Counter ElectrodeAllow the heat sintered slide to cool to room temperature.Once the slide has cooled, place the slide face down in the filtered dye and allow the dye to be absorbed for 5 or more minutes.While the first slide is soaking, determine which side of the second slide is conducting.Place the second slide over an open flame and move back and forth.This will coat the second slide with a carbon catalyst layer
Assembling the Solar CellAfter the first slide had absorbed the dye, it is quickly rinsed with ethanol to remove any water. It is then blotted dry with tissue paper.Quickly, the two slides are placed in an offset manner together so that the layers are touching. Binder clips can be used to keep the two slides together.One drop of a liquid iodide/iodine solution is then added between the slides. Capillary action will stain the entire inside of the slides
Preparation of Electrolyte SolutionElectrolyte solutionMeasure out 25-ml of acetonitrile.Weigh out 0.317-g of I2 or 0.05mM, add it to the acetonitirle and stir.Weigh out 1.6731 g of LiI 0.5mM and add it to the same.Stir and sore in a dark container with a tight lid.0.3mM N3 dye was taken and added to 10ml ethanol. N3 - RuL(NCS) (L=2,2-bipyridyl-4,4-dicarboxylic acid)
Electrochimica Acta 51 (2006) 38143819 Electrodeposited Pt for cost-efficient and flexible dye-sensitized solar cells Seok-Soon Kim, Yoon-Chae Nah, Yong-Young Noh, Jang Jo, Dong-Yu KimDye-sensitized solar cells Michael GrtzelLaboratory for Photonics and Interfaces, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland Journal of Photochemistry and Photobiology C: Photochemistry Reviews 4 (2003) 145153Takechi, K., Muszynski, R., Kamat, PV. Fabrication procedure of dye-sensitized solar cells (http://www.nd.edu/~pkamat/pdf/solarcell.pdf) B. ORegan, M. Grtzel, Nature 335 (1991) 737; M. Grtzel, Nature 414 (2001) 338344.http://chemwiki.ucdavis.edu/Analytical_Chemistry/Instrumental_Analysis/Cyclic_Voltammetryhttp://www.basinc.com/mans/EC_epsilon/Techniques/CPot/cp.html