太阳能电池(solar cells)

S.H.ZhengX.W.ChengH.ShenDate:2013.5.21contents1.Background2.Introduce3.Historyofsolarcells4.materialsofsolarcell5.fundamentalprinciple6.ProductionProcess7.classification8.Applicationsofsolarcell9.performancecomparisonofsolarcell10.Futureprospectsofsolarcell1.BackgroundWhyshouldwefocusonsolarcellsandmaterials?Sincethetwoindustrialrevolutions,fossilfuelssuchascoal,oil,naturalgashavebeenusedwildlyinsuccession.Whilethesearenon-renewableenergyandburningtoproducelargeamountsofcarbondioxidecausinggreenhouseeffect.背景1.Itisthemostabundantenergyofhumancanmakeuseof.2.Wherethereislight,thereissolarenergy.3.Itisakindofverycleanenergywithoutdamagetotheenvironment.whataboutsolarenergy?Thesolarcellisaimportantwayofsolarenergyutilization2.IntroductionAsolarcellisadevicethatconvertstheenergyofsunlightdirectlyintoelectricitybythephotovoltaiceffect.Photovoltaicsisthefieldoftechnologyandresearchrelatedtotheapplicationofsolarcellsinproducingelectricityforpracticaluse.Solarcelltechnologiesareanattractiveoptionforcleanandrenewableenergygenerationintheformofelectricity.Severaltechnologieshavebeendevelopedsince1950sandmanyofthemarenowreachedtoastageofcommercialization.Butphotovoltaicsolarelectricityisstillnoteconomicalincomparisontothegridpowerweusetoday.太阳能电池基本原理Materialsresearchstudies,aimedatfindingnewinexpensivesolarcellmaterialsandcombinationsofsemiconductorsandsemiconductor-metaljunctions.MethodicalresearchofcommonlyknownsolarcellssuchasSi,GaAs,Cu2S/CdS,etc.inordertoimproveefficienciesandfindnewcheapprocesses,bothinthehopetobringdownthecostofsolarenergytoacompetitiveevelwithclassicalenergysources.Twocategoriesofsolarcellresearch:3.HistoryofsolarcellIn1839FrenchphysicistA.E.Becquereldiscoveredthatlightcreatesabitofvoltagewhenitstrikesanelectrodecalledthephotovoltaiceffect.In1883thefirstsolarcellwasbuilt,byCharlesFritts,whocoatedthesemiconductorseleniumwithanextremelythinlayerofgoldtoformthejunctions.Thedevicewasonlyaround1%efficient.In1941thesiliconsolarcellwasinventedbyRussellOhl.ThoughtheefficiencyofOhl'scellwasonlyafractionbetterthantheseleniumcells,usingthelessexpensivesiliconasabasisforsolarcellswasasteptowardsgreaterefficiency.HistoryIn1954AmericansPearson,FullerandChapinbuiltanarrayofthinsiliconstrips,placedtheminthesunandturnedoutenergyatasix-percentefficiencyrate.Theircompany,BellLabs,builtanddeployedthefirstpracticalsolarbatteryjustoneyearlater,eventuallyachieving11-percentefficiency.Inthelate1950s,CherryandMandelorn,workingthroughtheU.S.SignalCorpslabs,helpeddevelopworkablesolarcellsfororbitalapplications.In1973theapplicationofsolarcelltransferedtothegeneralpurposeofthepeople'slivelihood.HistoryofsolarcellsMaterialsforsolarcellsinclude:•Silicon•GaAs/AlGaAs•CuInSe2(CIS)•CuGaInSe2(CGIS)•CdTeetc.AdvantagesofSilicon•Highertransferefficiency•Stability•Widespectrarange•Endurehighertemperature4.Materialsforsolarcell敏化纳米晶太阳能电池5.1Basicstructureofasolarcell·Aproperlydopedsemiconductorbaseb(eithern-orp-type)isthestartingmaterial.·Attheinterfacebetweenbandtaspacechargeregionwillbuildupwhichleadstoarectifiercharacteristic·Thetoporfrontlayertcanbeanoppositelydopedidenticalsemi-conductor(homo-junctioncell),achemicallydifferentsemiconductorwithalargergap(hetero-junctioncell),orathinmetalfilm,typically50-100Athick(Schottkybarrier).Inthelatterithasturnedouttobebeneficialtointroduceathininsulatingbarrierbetweenthesemiconductorandthemetaltoimprovetheopencircuitvoltageandthereforetheefficiency.敏化纳米晶太阳能电池N-typesiliconhasfreeelectrons.P-typesiliconhasfreeholes.WhenN-typeandP-typesiliconcomeintocontact,anelectricfieldformswithinthecell.Thesunilluminatesonthesemi-conductor'sp-njunctiontoformanewhole-electronpairs.Intheroleofthep-njunctionelectricfield,thelight-generatedholesflowtothep-typeregion,thephoto-generatedelectronflowtothenregion,connectedtothecircuittoformcurrent.敏化纳米晶太阳能电池5.2SolarcelloperationKeyaimistogeneratepowerby:Generatingalargeshortcircuitcurrent,IscGeneratealargeopen-circuitvoltage,VocMinimiseparasiticpowerlossmechanisms(particularlyseriesandshuntresistance).敏化纳米晶太阳能电池5.2.1ShortcircuitcurrentGenerationoflight-generatedcarries•Minimizereflection•Absorblightinsemiconductorandgeneratecarriers•Reflectionandabsorptiondependoncharacteristicsofsunlight,solarcellopticalpropertiesandsolarcellthickness.Theopticalpropertiesarekeyinachievinghighcurrent.Togenerateasmanycarrierspossibleweneedto:–Reducereflectionfromsilicon–Reducereflectionfrommetaltopsurface–IncreaseabsorptionoflightinsemiconductorCollectionoflightgeneratedminoritycarriers•Dependsonmaterialanddeviceparameters敏化纳米晶太阳能电池5.2.2OpencircuitvoltageIfcollectedlight-generatedcarriersarenotextractedfromthesolarcellbutinsteadremain,thenachargeseparationexists.Thechargeseparationreducestheelectricfieldinthedepletionregion,reducesthebarriertodiffusioncurrent,andcausesadiffusioncurrenttoflow.6.SolarPanelProductionProcess6.Productionprocess7.classificationClassificationbystructure•Homogeneoussectionsolarcells•Heterogeneoussectionsolarcells•SchottkysolarcellsClassif