DSSC染料敏化太阳能电池英文.pptx
TheorySchematic of Graetzel Cell第1页/共17页The adsorbed dye molecule absorbs a photon forming an excited state.dye*The excited state of the dye can be thought of as an electron-hole pair(exciton).The excited dye transfers an electron to the semiconducting TiO2(electron injection).This separates the electron-hole pair leaving the hole on the dye.dye*+The hole is filled by an electron from an iodide ion.2dye*+3I-2dye+I3-Theory第2页/共17页Theory:Charge SeparationCharge must be rapidly separated to prevent back reaction.Dye sensitized solar cell,the excited dye transfers an electron to the TiO2 and a hole to the electrolyte.In the PN junction in Si solar cell has a built-in electric field that tears apart the electron-hole pair formed when a photon is absorbed in the junction.第3页/共17页ObjectiveLearn about the photovoltaic effect.Understand the Scherrer formula.第4页/共17页Procedure:TiO2 SuspensionBegin with 6g colloidal Degussa P25 TiO2Incrementaly add 1mL nitric or acetic acid solution(pH 3-4)nine times,while grinding in mortar and pestleAdd the 1mL addition of dilute acid solution only after previous mixing creates a uniform,lump-free pasteProcess takes about 30min and should be done in ventilated hoodLet equilibrate at room temperature for 15 minutes第5页/共17页Procedure:Deposition of TiO2 FilmAlign two conductive glass plates,placing one upside down while the one to be coated is right side upTape 1 mm wide strip along edges of both platesTape 4-5 mm strip along top of plate to be coatedUniformly apply TiO2 suspension to edge of plate5 microliters per square centimeterDistribute TiO2 over plate surface with stirring rodDry covered plate for 1 minute in covered petri dish第6页/共17页Procedure:Deposition of TiO2 FilmAnneal TiO2 film on conductive glassTube furnace at 450 oC30 minutesAllow conductive glass to cool to room temperature;will take overnightStore plate for later use第7页/共17页Procedure:Preparing Anthrocyanin DyeNatural dye obtained from green chlorophyllRed anthocyanin dyeCrush 5-6 blackberries,raspberries,etc.in 2 mL deionized H2O and filter(can use paper towel and squeeze filter)第8页/共17页Procedure:Staining TiO2 FilmSoak TiO2 plate for 10 minutes in anthocyanin dyeInsure no white TiO2 can be seen on either side of glass,if it is,soak in dye for five more minWash film in H2O then ethanol or isopropanolWipe away any residue with a kimwipe第9页/共17页Procedure:Carbon Coating the Counter ElectrodeApply light carbon film to second SnO2 coated glass plate on conductive sideSoft pencil lead,graphite rod,or exposure to candle flame第10页/共17页Procedure:Assembling the Solar CellPlace two binder clips on longer edges to hold plates together(DO NOT clip too tight)Place 2-3 drops of iodide electrolyte solution at one edge of platesAlternately open and close each side of solar cell to draw electrolyte solution in and wet TiO2 filmEnsure all of stained area is contacted by electrolyteRemove excess electrolyte from exposed areasFasten alligator clips to exposed sides of solar cell第11页/共17页Procedure:Measuring the Electrical OutputAttach the black(-)wire to the TiO2 coated glassAttach the red(+)wire to the counter electrodeMeasure open circuit voltage and short circuit current with the multimeter.For indoor measurements,can use halogen lampMake sure light enters from the TiO2 sideMeasure current-voltage using a 1 kohm potentiometerThe center tap and one lead of the potentiometer are both connected to the positive side of the currentConnect one multimeter across the solar cell,and one lead of another meter to the negative side and the other lead to the load第12页/共17页ResultsOpen circuit voltage:0.388 V第13页/共17页Analysis:PowerMaximum Power:21 mWActive Area:0.7 in2 Max.power per unit area:30 mW/in2第14页/共17页QuestionsApproximate TiO2 particle size:assume 25 nm diameterNumber of TiO2 units per nanoparticle:Volume of one nanoparticle=8.18*10-18 cm3Density of TiO2 4 g/cm3 Mass of one nanoparticle=3.27*10-17 gMolar mass of TiO2=79.87 g/mol moles of TiO2 in one nanoparticle=4.10*10-19 moles4.10*10-19 moles*6.022*1023 molecules/mole=2.48*105 TiO2 units per nanoparticleNanoparticle surface area per gram:Number of nanoparticles per gram=1/(3.27*10-17)=3.06*1016 nanoparticlesSurface area of one nanoparticle=1.96*10-15 m2Surface area per gram=3.06*1016 nanoparticles/gram*1.96*10-15 m2/nanoparticle=60.0 m2/gram第15页/共17页QuestionsFraction of atoms that reside on the surface:Surface area of one particle=1.96*10-11 cm2Approximate atoms per unit area=1015 atoms/cm2Atoms on surface=1.96*10-11 cm2*1015 atoms/cm2=1.96*104 atomsFraction of atoms on surface=(1.96*104)/(2.48*105)=0.079Way to improve experiment:Filter raspberry juice using a better filter system第16页/共17页感谢您的欣赏！第17页/共17页
