平面异质结钙钛矿太阳能电池

1、RESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedLETTEREfficientplanarheterojunctionperovskitesolarcellsbyvapourdepositionMingzhenLid,MichaelB.Joh

2、nston1&HenryJ.Snaith1RESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.

3、ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedManydifferentphotovoltaictechnologiesarcbeingdevelopedforlarge-scalesolarenergyconversion1-4.Thewafer-basedfirst-generationphotovoltaicdevices1havebeenfollowedbythin-filmsol

4、idsemiconductorabsorberlayerssandwichedbetweentwochargc-sclcctivccontacts5andnanostructured(ormesostructured)solarcellsthatrelyonadistributedheterojunctiontogeneratechargeandtotransportpositiveandnegativechargesinspatiallyseparatedphases46Althoughmanymaterialshavebeenusedinnanostructureddevices,theg

5、oalofattaininghigh-cfficiencrthin-filmsolarcellsinsuchawayhasyettobeachieved7.Organomctalhalideperovskiteshaverecentlyemergedasapromisingmaterialforhigh-cfficicncynanostructureddevices*111.Hereweshowthatnanostructuringisnotnecessarytoachievehighefficiencieswiththismaterial:asimpleplanarheterojunctio

6、nsolarcellincorporatingvapour-depositedperovskiteastheabsorbinglayercanhavesolar-to-elcctricalpowerconversionefficienciesofover15percent(asmeasuredundersimulatedfullsunlight).Thisdemonstratesthatperovskiteabsorberscanfunctionatthehighestefficienciesinsimplifieddevicearchitectures,withouttheneedforco

7、mplexnanostructures.Witliinasolarcelltherearcmanydiftcrentcomponentswithdiscreterolesandhavingdifferenttolerancesforpurityandoptoelectronicproperties.Thehybridinorganic-organicsolarcellconceptismaterialagnostic*inthatitaimstousetheoptimummaterialforeachindividualfunction.Anymaterialthatiseasytoproce

8、ss,iiicxpcnsiveandabundantcanbeused,withtheaimofdeliveringahigh-efficiencysolarcell.HybridsolarcellshavebeendemonstratedinJi-conjugatedpolymerblendscontainingsemiconductornanocrystalssuchasCdSc(ref.12),CuInS2(ref.13)andPbS(ref.14).Dye-sensitizedsolarcellsarchybridsolarcellscontainingamesostructuredi

9、norganicn-typeoxide(suchasTiO2)sensitizedwithanorganicormetalcomplexdyeandinfiltratedwithanorganicp-typehole-conductor4.Recently,organomctaltrihatideperovskiteabsorberswiththegeneralformula(RNH3)BX3(whereRisCnH2d+iXisthehalogenI,BrorCl,andBisPborSn)1havebeenusedinsteadofthedyeindye-sensitizedsolarce

10、llstodeliversolid-statesolarcellswithapowerconversionefficiencyofover10%(refs&11,16).Evolvingfromthedye-sensitizedsolarcells,wefoundthatreplacingthemesoporousTiO2withmesoporousA12O3resultedinasignificantimprovementinefficiency,deliveringanopen-circuitvoltageofover1.1Vinadevicewhichwetermameso-supers

11、tructuredsolarcell%Wereasonthatthisobservedenhancementinopen-circuitvoltageisduetoconfinementofthephoto-excitedelectronswithinthepcrovskitcphase,therebyincreasingthesplittingofthequasi-Fermilevelsforelectronsandholesunderillumination,whichisultimatelyresponsibleforgeneratingtheopen-circuitvoltage.Fu

12、rtherremovalofthethermalsinteringofthemesoporousA12O3layer,andbetteroptimizationofprocessing,hasledtomeso-supcrstructurcdsolarcellswithmorethan12%efficiencyInaddition,CH3NH3PbI3-AC1Xcanoperaterelativelyefficientlyasathin-filmabsorberinasolution-processedplanarheterojunctionsolarcellconfiguration,del

13、iveringaround5%efficiencywhennomesostructureisinvolved17.Thispreviousworkdemonstratesthattheperovskiteabsorberiscapableofoperatinginamuchsimplerplanararchitecture,butraisesthequestionofwhethermesostructureisessentialforthehigliestefficiencies,orwhetherthethin-filmplanarheterojunctionwillleadtoasuper

14、iortechnologyHcreasameansofcreatinguniformflatfilmsofthemixedhalideperovskiteCH3NH3PbI3_乂CJweusedual-sourcevapourdeposition.InFig.1weshowanillustrationofthevapour-depositionset-up,alongwithanillustrationofaplanarheterojunctionp-i-nsolarcell(seeFig.lc)Fromthebottom(thesidefromwhichthelightisincident)

15、,thedeviceisconstructedonfluorine-dopedtinoxide(FTO)-coatedglass,coatedwithacompactlayeroftypeTiO2thatactsastheelectron-selectivecontact.Theperovskitelayeristhendepositedonthen-typecompactlayer,followedbythep-typcholeconductor,227,7/-tctrakis-(N,N-di-p-methoxyphenylamine)9,9/-spirobifluorene(spiro-O

16、MeTAD),whichensurestheselectivecollectionofholesatthesilvercathode.Giventhatthepurposeofthisstudywastounderstandandoptimizethepropertiesofthevapour-depositedperovskiteabsorberlayer,thecompactTiO2andthespiro-OMeTADholetransporterweresolution-processed,asisusualinmeso-supcrstructurcdsolarcells17InFig.

17、lb,wecomparetheX-raydiffractionpatternoffilmsofCH3NH3PbI3_AC1Xcithervapour-depositedorsolution-castontocompactTiO2-coatedFTO-coatcdglass.Themaindiffractionpeaks,assignedtothe110,220and330peaksat14.12,28.44and,respectively,43.23areinidenticalpositionsforbothsolution-processedandvapour-depositedfilms,

18、indicatingthatbothtechniqueshaveproducedthesamemixedhalidcperovskitewithanorthorhombiccrystalstructure8Notably,lookingcloselyintheregionofthe(110)diffractionpeakat14.12；thereisonlyasmallsignatureofapeakat12.65(the(001)diffractionpeakforPbl2)andnomeasurablepeakat15.68(the(110)diffractionpeakforCH3NH3

19、PbCl3)indicatingahighlevelofphasepurity.AdiagramofthecrystalstructureisshowninFig.Id.ThemaindifferencebetweenCH3NH3Pbl3andthemixcd-halideperovskitepresentedhereisevidentinaslightcontractionofthecaxis.ThisisconsistentwiththeClatomsinthemixed-halideperov-skitcresidingintheapicalpositions,outofthePbLip

20、lane,asopposedtointheequatorialoctahedralsites,ashasbeentheoreticallypredicted.Wenowmakeacomparisonbetweenthetliin-filmtopologyandcross-sectionalstructureofdevicesfabricatedbyeithervapourdepositionorsolutionprocessing.Thetop-viewscanningelectronmicroscope(SEM)imagesinFig.2a,bhighlighttheconsiderable

21、differencesbetweenthefilmmorphologiesproducedbythetwodepositionprocesses.Thevapour-depositedfilmsarcextremelyuniform,withwhatappeartobecrystallinefeaturesonthelengthscaleofhundredsofnanometres.Incontrast,thesolution-processedfilmsappeartocoatthesubstrateonlypartially,withcrystallineplateletsonthelen

22、gthscaleoftensofmicrometres.Thevoidsbetweenthecrystalsinthesolution-processedfilmsappeartoextenddirectlytothecompactTiO2-coatedFTOcoatedglass.Thecross-sectionalimagesofthecompleteddevicesinFig.2c,drevealmoreinformationaboutthecrystalsize.Thevapour-depositedperovskitefilm(Fig.2c)isuniformandsimilarin

23、appearancetotheFTOlayer,albeitwithslightlylargercrystalfeatures.Thesolutioprocessedperovskitefilm(Fig.2d)isextremelysmoothintheSEMOrganicInorganicsourcesource11)(2?IlliSolution-processed)(330).flVapour-depositedA上*Illi1020304050602&)Figure1|Materialdepositionsystemandcharacterizationa、Dual-sourcethe

24、rmalevaporationsystemfordepositingtheperovskiteabsorbers;theorganicsourcewasmethylammoniumicxiideandtheinorganicsourcePbCLb*raydiffractionspectraofasolution-processedperovskitefilm(blue)andvapourdepositedperovskitefilm(red).Thebaselineisoffsetforeaseofcomparisonandtheintensityhasbeennormalized.cGene

25、ricstructureofaplanarheterojunctionp-i-nperovskitesolarcell,d、CrystalstructureoftheperovskiteabsorberadoptingtheperovskiteABX5form,whereAismethylammonium.BisPbandXisIorCl.image,consistentwithmuchlargercrystalgrainsizethanthefieldofview.Forbothofthesefilmsthecrystalsizesarelargerthanwearcabletodeterm

26、inefromthepeakwidthoftheX-raydiffractionspectra(about400nm),owingtomachinebroadening.Onzoomingout,thevapour-depositedfilminFig.2cremainsflat,havinganaveragefilmthicknessofapproximately330nm.Incontrast,thesolution-processedfilminFig.2fhasanundulatingnature,withfilmthicknessvaryingfrom50to410nm.Notabl

27、y,thiscross-sectionisstillwithinasingleplateletandsoevengreaterlong-rangeroughnessoccursowingtotheareaswheretheperovskiteabsorberiscompletelyabsent(athicknessvariationfrom0to465nmwasobservedinmultipleSEMimages).Thecurrent-dcnsity/voltagecurvesmeasuredundersimulatedAM1.5,101mWcm-2irradiance(simulated

28、siuilight)forthebest-performingvapour-depositedandsolution-processedplanarheterojunctionsolarcellsarcshowninFig.3Themostefficientvapour-depositedperoskitedevicehadashort-circuitphotocurrentof21.5mAcm-*2,anopen-circuitvoltageof1.07Vandafillfactorof0.6&yieldinganefficiencyof15.4%Inthesamebatch,thebest

29、solution-processedplanarheterojunctionperovskitesolarcellproducedashort-circuitphotocurrentof17.6mAcmJanopcn-circuitvoltageof0.84Vandafillfactorof0.5&yieldinganoverallefticicncyof8.6%.InTable1weshowtheextractedperformanceparametersforthesebest-performingcellsandtheaveragewithstandarddeviationofabatc

30、hof12vapourdepositedperovskitesolarcellsfabricatedinanidenticalmannertothebest-performingcell.Dual-sourcevapourdepositionresultsinsuperioruniformityoftliecoatedperovskitefilmsoverarangeoflcngtliscales,whichsubsequentlyresultsinsubstantiallyimprovedsolarcellperformance.Inoptimizingplanarheterojunctio

31、nperovskitesolarcells,perovskitefilmthicknessisakeyparameter.Ifthefilmistoothin,thenthatregionwillnotabsorbsufficientsunliglit.Ifthefilmistoothick,thereisasignificantchancethattheelectronandhole(orexciton)diffusionlengthwillbeshorterthanthefilmthickness,andthatthechargewillthereforenotbecollectedatt

32、hep-typeandn-typcheterojunctions.Furthermore,thecompleteabsenceofmaterialfromsonicregionsinthesolution-processedfilms(pinholes)willresultindirectcontactofthep-typespiro-OMcTADandtheTiO2compactlayer.Thisleadstoashuntingpaththatisprobablypartiallyresponsibleforthelowerfillfactorandopcn-circuitvoltagei

33、nthesolution-castplanarheterojunctiondevices17,19.Indeed,itisremarkablethatsuchinhomogeneousandundulatingsolution-castfilmscandeliverdeviceswithover8%efficiencyTheresultspresentedheredemonstratethatsolidperovskitelayerscanoperateextremelywellinasolarcell,andinessencesetalowerlimitof330nm(thefilmthic

34、kness)ontheelectronandholediffusionlengthinthisperovskiteabsorber.However,moreworkisrequiredtodeterminetheelectronandholediffusionlengthspreciselyandtounderstandtheprimaryexcitationandthemechanismsforfrce-chargcgenerationinthesematerials.Adistinctadvantageofvapourdepositionoversolutionprocessingisth

35、eabilitytopreparelayeredmulti-stackthinfilmsoverlargeareas.Vapourdepositionisamaturetechniqueusedintheglazingindustry,theliquid-crystaldisplayindustryandthethin-tilmsolarcellindustry,amongothers.Vapourdepositioncanleadtofulloptimizationofelectroniccontactatinterfacesthroughnniltilayerswithcontrolled

36、levelsofdoping20,asisdoneinthecrystallinesiliconheterojunctionwithtliinintrinsiclayer*solarcell21andinthin-tilmsolarcells：Additionally,organiclight-emittingdiodes22,23haveprovedtobecommerciallysound,withdeviceswithextremelythinmultilayerstacksfabricatedbyvapourRESEARCHLETTERdoi:10.1038/naturel2509de

37、partmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER201

38、3IVOLSOIINATUREI39S2013MacmillanPublishersLimited.Allrightsreserved396|NATURE1VOLSOII19SEPTEMBER20132013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI

39、39S2013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedaVapour-depositedSolutioreprocessedeFigure2|Th

40、in-filmtopologycharacterizationa.b,SEMtopviewsofavapour-depositedperovskitefilm(a)andasolutioprocessedperovskitefilm(b).cd、Cross-sectionalSEMimagesunderhighmagnificationofcompletesolarcellsconstructedfromavapour-depositedperovskitefilm(c)andasolution-processedperovskitefilm(d).e、fCross-sectionalSEMi

41、magesunderlowermagnificationofcompletedsolarcellsconstructedfromavapourdepositedperovskitefilm(e)andasolution-processedperovskitefilm(f)RESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013Macmi

42、llanPublishersLimited.Allrightsreserveddcposition.Smallmolecularorganicphotovoltaicshavealsobeenabletocompetedirectlywithsolution-processedorganicphotovoltaicsdespitemuchlowerlevelsofresearchanddevelopment,becausewithFigure3|Solarcellperformance.Current-density/voltagecurvesofthebest-perfonningsolut

43、ionprocessed(bluelines,triangles)andvapour-deposited(redlines,circles)planarheterojunctionperovskitesolarcellsmeasuredundersimulatedAM1.5sunlightof101mWcm2irradiance(solidlines)andinthedark(dashedlines).Thecurvesareforthebest-performingcellsmeasuredandtheirreproducibilityisshowninTable1.vapourdeposi

44、tionthecharge-collectioninterfacescanbecarefullytuncdandmulti-junctionarchitecturesarcmorestraightforwardtorealize24.Aninterestingpossibilityforthecurrentvapour-depositedperovskitetechnologyistouseitasatopcelFinahybridtandemjunctionwithcitlicrcrystallinesiliconorcopperindiumgallium(di)s-elenide.Alth

45、oughultimatelyanall-perovskite*multi-junctioncellshouldberealizable,theperovskitecellshavenowachievedaperformancctliatissufficienttoincreasetheabsoluteefficiencyofhigh-efficicncycrystallinesiliconandcopperindiumgallium(di)selcnidesolarcells25.Additionally,becausevapourdepositionoftheperovskitelayers

46、isentirelycompatiblewithconventionalprocessingmctliodsforsilicon-wafer-basedandthin-filmsolarcells,theinfrastructurecouldalreadybeinplacetoscaleupthistechnologyWehavebuiltvapour-depositedorganometaltrihalidcperovskitesolarcellsbasedonaplanarheterojunctionthin-filmarchitecturethathaveasolar-toclcclri

47、calpowerconversionefficiencyofover15%withanopen-circuitvoltageof1.07V.Theperovskiteabsorbersseemtobeversatilematerialsforincorporationintohighlyefticicntsolarcells,giventhelow-tcmpcratureprocessingtheyrequire,theoptionofusingeithersolutionprocessingorvapourdepositionorboth,thesimplifieddevicearchite

48、ctureandtheavailabilityofmanyothermetalandorganicsaltsthatcouldformaperovskitestructure.WhethervapourdepositionemergesasthepreferredrouteformanufactureorsimplyrepresentsabenchmarkmethodforfabricatingextremelyuniformRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.Clarendon

49、Laboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimi

50、ted.Allrightsreserved19SEPTEMBER2013|VOL501|NATURE|3972013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.Allrightsres

51、ervedTable11SolarcellperformanceparametersCurrentdensity(mAcm今Open-circuitvoltage(V)FillfactorEfficiency(%)Vapour-deposited21.51.070.6715.4Vapour-deposited(averages.d.)50.030.620.0512.32.0Solutioreprocessed17.60.840.588.6Solarcellperformanceparametersareextractedfromthecurrent-voltagecurve

52、spresentadinFig.3.Theaverageandstandarddeviation(s.d)valuesofabatchof12identicallyprocessedplanarheterojunctionvapour-depositedCHNHsPb-Qperovshtesolarcellsarealsoshown.RESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBE

53、R2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.AllrightsreservedRESEARCHLETTERdoi:10.1038/naturel2509departmentofPhysics.UniversityofOxford.ClarendonLaboratory.ParksRoad.Oxford0X13PU.UK.19SEPTEMBER2013IVOLSOIINATUREI39S2013MacmillanPublishersLimited.Allrightsreservedfilms(thatwillultimatelybe

54、matchedbysolutionprocessing)remainstobeseenFinally,akeytargetforthephotovoltaicscommunityhasbeentofindawider-bandgaphighlycfticienttopcell；toenablethenextstepinimprovingtheperformanceofcrystallinesiliconandexistingsecond-generationthin-filmsolarcells.Thisperovskitetechnologyisnowcompatiblewiththesef

55、irst-andsecondgcncraliontechnologies,andishencelikelytobeadoptedbytheconventionalphotovoltaicscommunityandindustryTherefore,itmayfinditswayrapidlyintoutility-scalepowergeneration.METHODSSUMMARYTheperovskiteabsorberwasdepositedbyadualsounzeevaporationsystem(KurtJ.LeskerMiniSpectros)withceramiccrucibl

56、es(organiclight-emittingdiodesources)inanitrogentilledglovebox.Ihevapour-depositedperovskitedeviceswerefabricatedonFTO-coatedglass.AcompactlayerofTiO2wasdepositedontheFTO-coatedglassbyspin-coating(solution-processing)itwithamildlyacidicsolutionoftitaniumisopropoxideinethanolGreen.M.A.Siliconphotovol

57、taicmodules:abriefhistoryofthefirst50years.Prog.PhotovoltRes.Appl.13,447-455(2005).Graetzel.M.,Janssen.R.A.J.,Mitzi.D.B.&Sargent.E.H.Materialsinterfaceengineeringforsolution-processedphotovoltaics.Nature488.304-312(2012).Chopra.K.L.Paulson,P.D.&Dutta,V.Thin-filmsolarcells:anoverview.Prog.PhotovoltRe

58、s.Appl.12,69-92(2004).ORegan.B.&Gratzel.M.Alow-cost,high-efficiencysolarcellbasedondye-sensitizedcolloidalTi02films.Nature353,737-740(1991).Halls,J.J.M.etal.Efficientphotodiodesfrominterpenetratingpolymernetworks.Nature376,498-500(1995).Yu.G.Hummelen,J.C.,Wudl.F.&Heeger.A.J.Polymerphotovoltaiccells:

59、enhancedefficienciesviaanetworkofinternaldonor-acceptorheterojunotions.Sc/ence270.1789-1791(1995).Green.M.A.Emery.K“Hishikawa,Y.Warta.W.&Dunlop.E.D.Solarcellefficiencytables(version40).Prog.PhotovoltRes.Appl.20.606-614(2012).andsubsequentlytheperovskiteabsorberwasdepositedonthecompactTiO2-coatedFTOs

60、ubstrateMethylammoniumiodide(CH3NH3I)andleadchloride(PbCL)weretheorganicandinorganicprecursorsalts,evaporatedsimultaneouslyfromseparatesourcesat10snibarwithanasdepositedmolarratioof4:1、basedonthereadingofthesensorsabovethecrucibles.Adarkreddish-browncolourwasobservedimmediatelyafterevaporation.Annea