metionedwww

2012WILEY-VCHVerlagGmbH&Co.
KGaA,Weinheim6335www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
comCOMMUNICATIONFromBinarytoTernarySolvent:MorphologyFine-tuningofD/ABlendsinPDPP3T-basedPolymerSolarCellsLongYe,ShaoqingZhang,WeiMa,*BenhuFan,XiaGuo,YeHuang,HaraldAde,andJianhuiHou*Inthepastdecade,greatsuccesseshavebeenachievedinbulkhetero-junction(BHJ)polymersolarcells(PSCs)inwhichdonor/acceptor(D/A)bi-continuousinterpenetratingnetworkscanbeformedresultinginahighpowerconversionefciency(PCE);insomerecentstudies,PCEsthatapproach8%haveevenbeenreported.
[1,2]Inadditiontotheintrinsicproper-tiesofactivelayermaterials,suchasbandgapsandmolecularenergylevels,morphologicalpropertiesoftheD/Ablendsincludingcrystallinityofpolymers,domainsize,materialsmiscibility,hierarchicalstructures,andmolecularorientationarealsoofgreatimportanceforthephotovoltaicperformanceofthedevices.
[3–8]Therefore,severalstrategiesincludingslowgrowth,[9]solventannealing,[10]thermalannealing,[11]selectionofsolvent[12]ormixedsolvent[13]havebeenappliedtomodifyorcontrolthemorphologyoftheD/Ablends.
Amongthese,binarysolventmixtureshavebeensuccessfullyusedinmor-phologycontrol.
Forexample,thedichlorobenzene(DCB)orchlorobenzene(CB)/1,8-diiodooctane(DIO)binarysolventsystemhasbeenwidelyappliedinPSCdevicefabricationproc-esses.
BymixingafewvolumepercentofDIOwiththehostsolvent(DCBorCB),theefcienciesofmanypolymerscanbeimproveddramatically.
[1,14]BesidesDIO,othersolvents,like1,8-octanedithiol(OT),[15]N-methyl-2-pyrrolidone(NMP),[13,16]1-chloronaphthalene(CN),[16,17]andchloroform(CF),[18,19]canalsobeused.
Accordingtotheseworks,itcanbeconcludedthatcrystallinity,aswellasdomainsizeintheblendscanbetunedeffectivelybyusingbinarysolventmixtures,andthusbinarysolventmixturesplayaveryimportantroleinhighperform-ancePSCs.
Conjugatedpolymerswithdiketopyrrolopyrrole(DPP)unitsarewidelyusedinorganicphotovoltaicstoobtainhighefcientultra-lowband-gapmaterialswithhighlyefcientphotovoltaicproperties.
[19–26]Asknown,photovoltaicperformanceofthePSCsbasedonDPP-containingpolymersisquitesensitivetomorphologyoftheD/Ablends.
Therefore,howtoselectasuitablesolventsystemtomakethesolutionoftheactivelayermaterialsisoneofthekeyissuesinmakinghighlyefcientPSCsbasedonDPP-containingPolymer/fullereneblends.
Forinstance,whenpureCFwasusedinprocessingtheblendofPDPP3T/PC71BM,[21]onlyamodestPCEwasobtained,byusingaCF/DIObinarysolvent,i.
e.
,addsmallamountofDIOasprocessingadditiveduringthesolutionprocessingoftheblend,thePCEofthePSCdevicecanbedramaticallyincreasedto5%.
However,consideringthatPDPP3Thasaverybroadabsorptionbandcoveringtherangefrom400to900nmbuttheoptimumshortcircuitcurrentdensity(JSC)reportedinpre-viousworkis11.
8mA/cm2only,thereshouldbemuchspaceforimprovingJSCandthusPCEofthedevice.
Comparedtobinarysolventmixtures,ternarysolventmix-turesattractedmuchlessattentionfromtheeldofPSCs,thoughtheyhavebeensuccessfullyusedinotherapplications,suchasliquidchromatography[27]and,electrochemistry,[28]etc.
Therefore,itisinterestingandalsomeaningfultoinvestigatetheutilityofternarysolventmixturestoPSCactivelayerfab-rication.
Herein,aDCB/CF/DIOternarysolventsystemwasemployedtooptimizethemorphologyandthustoimprovethephotovoltaicperformanceofthePDPP3T/PC71BMblendlms.
Sinceitisquitelaborioustodoafullscanforthreevariablesinonestudy,atwo-stepstrategywasadoptedforthepresentsolventinvestigationasthefollowings:1)tooptimizepho-tovoltaicperformanceofPDPP3T-basedPSCsbytuningthevolumeratioofthetwoingredients(DCBandCF)ofthebinarysolvent;2)tomakefurtherimprovementofphotovoltaicper-formancebyaddinganotheringredient(DIO)intothebinarysolventwiththeoptimalDCB/CFratioobtainedfromstep1.
ThephotovoltaicresultsindicatethatphotovoltaicperformanceofthePDPP3T-basedPSCscanbeimprovedeffectivelybythistwo-stepoptimization.
Furthermore,themorphologicalevolu-tionoftheblendsduringthistwo-stepoptimizationprocesswasdemonstratedbyatomicforcemicroscopy(AFM),resonantsoftX-rayscattering(RSoXS)andgrazing-incidencewideangleX-rayscattering(GIWAXS)measurements.
Tothebestofourknowledge,thisworkdemonstratestherstsuccessfulexamplefortheapplicationofternarysolventmixtureinPSCdevicefabrication.
AsillustratedinFigure1b,aconventionalPSCdevicestructure,ITO/PEDOT:PSS(35nm)/PDPP3T:PC71BM/CaL.
Ye,S.
Zhang,B.
Fan,X.
Guo,Y.
Huang,Prof.
J.
HouStateKeyLaboratoryofPolymerPhysicsandChemistryBeijingNationalLaboratoryforMolecularSciencesInstituteofChemistryChineseAcademyofSciencesBeijing100190,P.
R.
ChinaE-mail:hjhzlz@iccas.
ac.
cnDr.
W.
Ma,Prof.
H.
AdeDepartmentofPhysicsNorthCarolinaStateUniversityRaleigh,NC27695,USAE-mail:wma5@ncsu.
eduL.
Ye,X.
GuoGraduateUniversityofChineseAcademyofSciencesBeijing100049,P.
R.
ChinaDOI:10.
1002/adma.
201202855Adv.
Mater.
2012,24,6335–63416336www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATION(20nm)/Al(80nm),wasusedinthiswork.
TheD/Aratio(PDPP3T/PC71BM,wt/wt)wasoptimizedbyusingDCBastheprocessingsolventpriortothestudyofmixedsolvents,andwefoundthattheoptimalD/Aratiois1:2,whichisconsistentwiththereportedwork.
[21]Then,binarysolventmixturesofDCBandCFwerechosenastheprocessingsolvents,anddifferentvolumeratios(DCB/CF,v/v),from1:4to4:1,werescanned.
J–VcurvesofthePSCdevicesfabricatedbyusingthebinarysol-ventsareshowninFigureS1a,andthephotovoltaicresultsofthePSCdevicesarelistedinTableS1.
Furthermore,thedataforDCB/DIO(95:5,v/v)arealsolistedinTableS1forreference.
ItcanbeseenthatthebestphotovoltaicperformancewithaPCEof5.
38%wasrecordedwithaopencircuitvoltage(VOC)of0.
68V,aJSCof11.
27mA/cm2andallfactor(FF)of70.
08%,whenDCB/CF4:1(v/v)wasusedinthebinarysolvents.
ThedesirableresultexceedsthehighestPCE(4.
7%)achievedbyCF/DIOco-solvent.
[21]Successively,DIOwasusedasthethirdingredientintheprocessingsolventmixtures.
Inordertogetaoptimumfor-mulaoftheternarysolventforachievinghighPCE,thecontentofDIOwasscanned.
DCBandCFmixturewitha4:1DCB/CFratio(v/v)wasusedasthehostsolventtomakeasolutionofPDPP3T/PC71BM,andthen1%,3%,5%or8%DIOwasaddedpriortospin-coatingprocess.
TheJ-Vcurvesofthedevicesfab-ricatedbyusingdifferentDIOratiosareplottedinFigureS1b,andthedetailedphotovoltaicresultsanddeviceparametersarelistedinTableS2.
TheJ-Vcurvesofthethreerepresenta-tivedevicesareshowninFigure2aandTable1,anditcanbeseenthatwhentheternarysolvent(DCB/CF/DIO)wasused,JSCofthedevicecanbeimprovedeffectivelywithslightlysac-ricingtheFF.
Therefore,thechampiondevicewasobtainedwhena5%DIOwasaddedduringthespin-coatingprocess,andtheoptimalcompositionoftheternarysolventisDCB/CF/DIO=76:19:5(v/v/v).
APCEof6.
71%wasrecordedfromthechampiondevice,whichisthehighestoneforDPP-basedBHJPSCs.
Thecorrespondingexternalquantumefciency(EQE)curvesofthethreedevicesmetionedaboveareshowninFigure2b.
TheEQEcurvesindicatethatthePSCdeviceshavebroadresponseinthewavelengthrangefrom300nmto900nm.
SincethepolymerPDPP3Tshowsweakabsorptioninshortwavelengthregion,theresponseofthedevicesintheregionfrom400nmto600nmshouldbeduetotheabsorptionofPCBMandtheresponseinlongwavelengthisascribedtothepolymer.
ThecomparisonamongthesethreeEQEcurvesrevealthat:a)inthedeviceproc-essedbypureDCB,PC71BMworksbetterthanthepolymer;b)inthedeviceprocessedbytheDCB/CFbinary-solvent,thequantumyieldfromthepolymerbecomesbetterwhilethatfromPC71BMdecreasesobviously;c)inthedeviceprocessedbytheternarysolvent,thequantumyieldinthewholeresponseregionisimprovedeffectively.
Addition-ally,forthedeviceprocessedfromtheter-narysolvent,theintegralcurrentdensitydeducedbyEQEcurveandtheglobalrefer-encespectrumyieldedaparticularlyhighJSCof15.
22mA/cm2.
ThedifferencebetweenmeasuredJSCandthecalculatedcurrentdensityvalueiswithin5%,indicatingthatthephotovoltaicmeasurementisreliable.
Grazing-IncidenceWideAngleX-rayscattering(GIWAXS)isusedtoprovidethestructuralinformationsuchascrystallitesize,intermoleculardistanceandcrystalliteorientationinblendFigure2.
J–V(a)andEQE(b)curvesofthePSCsprocessedfromDCB,DCB/CF(4:1,v/v)andDCB/CF/DIO(76:19:5,v/v/v).
-0.
20.
00.
20.
40.
60.
8-20-15-10-50510CurrentDensity(mA/cm2)Voltage(V)DCBDCB/CFDCB/CF/DIO(a)30040050060070080090010000102030405060EQE(%)Wavelength(nm)DCBDCB/CFDCB/CF/5%DIO(b)Figure1.
(a)MolecularstructuresofPDPP3Tand(b)devicestructurediagram.
Adv.
Mater.
2012,24,6335–63416337www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATIONnear1.
71,whichappearedforalltheblendlms.
Wenotedthatthe(010)π–πstackingpeaksaremorepronouncedinout-ofplanedirectionthanin-planedirection,whichindicatesthatoverallapreferentialface-oncrystalorientationwasformedinblendlms.
Theface-onorientationisconsideredtobedesirableforimprovedholetransport.
However,onlyminordif-ferencesbetweenthethreesamplesareobserved.
Furthermore,byperformingaScherreranalysisonout-ofplane(100)and(010)peaks,thesizeofcrystalandthesizeofπ–πstackswereobtained(seeTableS3).
NosignicantdifferencesofcrystalsizearedetectedamongblendlmsprocessedwithDCB,DCB/CFandDCB/CF/DIO(7.
5nm,7.
8nmand8.
5nm,respectively).
Forthesizeofπ–πstacks,smallersizeisfoundforDCBproc-essedlms(ca.
2.
0nm),butlittlevariationisobservedforDCB/CFandDCB/CF/DIO(ca.
4.
3nmand4.
5nm,respectively).
Thisobservationmirrorstheabovediscussionthatcystallinitycannotalwaysbereadilycorrelatedtothedeviceperformance.
Toinvestigatethenanoscaletopographynetworks,AFMisemployedtomeasurethesurfacemorphology.
TheheightandphaseimagesofthePDPP3T/PCBMblendspreparedbyusingsolventswithdifferentcompositionsareshowninFigure4,andthemorphologyevolutionoftheblendlmscanbewelldemon-strated.
Fromthecomparisonoftopographies(Figure4a,4band4c),themeansquaresurfaceroughness(Rq)ofthreeblendlmsare0.
86nm,2.
63nm,4.
09nmfortheblendlmsprocessedfrompureDCB,DCB/CF,DCB/CF/5%DIO,respectively.
Moredetailedcomparisonamongthephaseimagesofthelmsrevealsanotherfeature:althoughnanoscalephaseseparationcanbeobservedinthelmprocessedbypureDCB,theedgesofthedomainsareveryblurry(seeFigure4d),whileforthelmsprocessedbythelmsofBHJPSCs.
Figure3showstheout-of-plane(Figure3b)andin-plane(Figure3c)GIWAXSprolesofthePDPP3T/PC71BMblendlmsprocessedwithdifferentsolvents.
FromFigure3b,itisclearthatthe(h00)crystallinityofthelmproc-essedwithDCBwaslowandonlya(100)peakcanbeobserved.
WhenDCB/CFwasused,pronounced(100)and(200)reectionpeaksareobserved.
WhenDCB/CF/DIOwasemployed,threepronouncedreectionpeaks,(100),(200),and(300)canbeobservedclearly,indicatingthatlamellarstackingoftheblendlmsisfurtherimproved.
Asimilartrendcanalsobeobservedfromthein-planeGIWAXSprolesasshowninFigure3c.
However,itisnotthoughtthatchargegenerationandtrans-portoccursinthisdirectionofpolymercrystalandresultingwithimprovingdeviceperformance,althoughanenhancedpolymerlamellarstackingisindeedobserved.
The(010)π–πstackingpackingreectionpeaks,thedirectioncorrespondingtochargetransport,arerevealedinbothFigure3band3catqTable1.
PhotovoltaicresultsofPSCsprocessedbydifferentsolvents.
ProcessingSolventVOC[V]JSC[mA/cm2]FF[%]PCE[%]Rs[Ωcm2]μha)[cm2/(Vs)]PureDCB0.
6512.
5759.
984.
8710.
085.
2*104DCB/CF(4:1,v/v)0.
6811.
2770.
085.
385.
211.
4*103DCB/CF/DIO(76:19:5,v/v/v)0.
6615.
4165.
926.
715.
933.
9*103a)CalculatedbySCLCmethod.
Figure3.
2Dpattern(a),out-of-plane(b)andin-plane(c)GIWAXSdataofPDPP3T:PC71BMblendlmspreparedbyDCB,DCB/CF(4:1,v/v)andDCB/CF/DIO(76:19:5,v/v/v).
Adv.
Mater.
2012,24,6335–63416338www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATIONTherelativedomainpurityofanassumedtwo-phasesystemcanbeextractedbyintegratingscatteringprolesviatotalscatteringintensity(TSI)[30](seeSupportingInforma-tionfordetails).
Thepurerthedomainsare,thehighertheTSI.
RelativeTSIvaluesof0.
79,0.
93,and1areobtainedforDCB,binaryandternarysolvents,respectively.
ThedomainsbecomemorepurewhenDCBismixedwithCFandfurtherimprovementofrelativedomainpuritycanbeachievedbyaddingDIO.
binaryandternarysolvents,sharpandblurryedgesofthebrildomainscanbeobservedrespectively(seeFigure4eand4f).
Con-sideringthatthesurfacetextureneedstobeconsideredwithcareandmightnotreectthebulkmorphology,wewillshowbelowthoughthattheAFMobservationcorrelatetothesharpnessofthedomainboundariesinferredfromthePorodscalingexponentsobservedforscatteringfromthebulkmorphology.
Characterizationofthebulkmorphology,therelativedomainpurity,andinterfacialstructurecanbeachievedwithresonantsoftX-rayscattering(R-SoXS).
[29]Aphotonenergy284.
5eVwasutilizedtoprovidehighmaterialcontrastbetweenPDPP3TandPC71BM(seeFigureS3).
Figure5showstheR-SoXSdataforPDPP3T:PC71BMblendsprocessedwithDCB,DCB/CFandDCB/CF/DIOsolvents,alongwithatofthehighq-datatoapowerlawandabackgroundtoaccountforx-rayuorescence(Fordetails,seeSupportingInformation).
Wenotethattheloca-tionofthepeak,thescatteringintensitiesandthedistributionofR-SoXSpatternsareclearlysensitivetowhichprocessingsolventisused.
Thelocationofpeaksrepresentsthedominantdomainspacingofdonortodonororfromacceptortoacceptorphases.
Thescatteringprolesrepresentthedomainsizedis-tributionatlowandmediumq,i.
e.
structurefactor,whereasatveryhighq,thescalingoftheintensityrelatestothesharpnessoftheinterfaces(Porodregime).
Itwasobservedthatoverall,thebulkmorphologyexhibitslargerdomainsthanobservedwithAFM.
Specically,thePDPP3T/PC71BMblendlmsproc-essedbyDCBhadthecoarsestmorphologywithadominantdomainspacingof81nm.
Incontrast,whenthebinary(DCB/CF)andtheternary(DCB/CF/DIO)solventwereusedinthelmfabrication,thedominantdomainspacingwasreducedto71nm.
Notably,theDCBsamplehasthehighestscatteringintensityatlowqandadispersionofdomainssize,whereastheDCB/CF/DIOsampleshasthehighestintensityathighq,andtheDCB/CFsamplesthemostnarrowdispersionofsize.
Figure4.
AFMtopographyandphaseimages(2μm*2μm)ofPDPP3T/PC71BMblendlmsprocessedbyDCB(a,d),DCB/CF(4:1,v/v)(b,e),andDCB/CF/DIO(76:19:5,v/v/v)(c,f).
Figure5.
R-SoXSinformationofPDPP3T/PC71BMblendlmspreparedatvariousconditions:DCB,DCB/CF(4:1,v/v),DCB/CF/DIO(76:19:5,v/v/v).
Thepeaklocationsaremarkedbythearrows.
Thetotalscatteringintensityandthescalingexponentsathighqarealsoindicated.
Adv.
Mater.
2012,24,6335–63416339www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATIONawidedistributionofdomainssize,withthemostimpuredomainsandsomewhatroughinterfaces.
Thisleadstoahighexcitondissociationefciency,hencegoodJSC,butatacostofbi-molecularrecombinationandreductioninFF.
Generally,thePCBMdomainsareratherpureandimpurityofthedomainsisgenerallyduetoPCBMdispersedintheamorphousportionofthepolymer.
[30]ThiswouldbeconsistentwiththerelativebadEQEofthepolymerasshowninFigure2b.
TheadditionofCFtoDCBleadstoamarkedimprovementindomainpurityandreduceddomainsizewithsharperinterfaces.
Therefore,theholemobility(μh)oftheblendwasimprovedfrom5.
2*104to1.
4*103cm2/(V·s),andthisleadstothebestFF.
However,theoveralldomainsizeistoolargeforefcientchargesepara-tion,andtheJSCisnotmuchchangedrelativetoDCBalone.
WithDIOaddedtoDCB/CF,theoveralldomainsizeisnotchangingmuch,buttherougherinterfacesprovideashorteraveragedistancefromtheaveragelocationofthephotonabsorptionsitetothedonor/acceptorinterface.
ThisenhancesexcitondissociationandthusJSC.
Theslightlyincreasedpurityishowevernegatedbytheenhancedbi-molecularrecombina-tionattheroughinterfaceswithaconcomitantreductioninFF.
Consequently,theseriesresistance(Rs)decreasesfromtheini-tialvalueof10.
08to5.
21Ω·cm2andthenslightlyincreasesto5.
93Ω·cm2,whentheprocessingsolventsuccessivelychangefromsinglesolventtoternarysolvent.
Thiswouldbeanalo-goustothesituationobservedforPFB/F8BT.
[8]MonteCarlosimulationsandamoredetailedstudyofthescatteringscalingbehaviorforalargerrangeofsolventswouldbehelpfultofur-therelucidatetherelativeimportanceoftheinterface.
Presently,evenjusttherawdataclearlyindicatesthattheinterfacesareroughlyoftwotypesanddetailedcharacterizationisoutsidethescopeofthisrstreportoftheuseofternarysolventmixture.
Inconclusion,byincorporatingthreefunctionalsolventsasprocessingsolventforthersttime,weareabletocreateThescalingathighqisalsoratherinformative.
Twosituationsareobserved.
TheDCB/CFsampleexhibitscalingexponentof–4.
35,whichindicatesthattheinterfacesaresmoothandrathersharp,i.
e.
onlyslightlyinterdiffused(anidealsharpinterfacehasascalingexponentof–4).
[31,32]ThepureDCBsampleandtheDCB/CF/DIOsamplesshowexponentsofapproximately–3.
31,whileindicatesthattheinterfacesinthesesamplesaresomewhatroughandpossiblyfractalinnature,leadingtoaccessscatteringrelativetoperfectlysharpandsmoothinterface.
Theinterfacecharacter-isticsappeartobedrivenbyCFwhenCFisaddedtoDCB(seeFigureS4),theeffectofwhichisnegatedandtheinterfacestruc-turerevertsbacktothatofDCBwhentheDIOisadded.
Overall,threeparametershavebeenextractedfromtheR-SoXSdata:Thedominantdomainsizeanddomainsizedis-tribution,theoverallrelativedomainpurity,andthenatureofthedonor-acceptorinterface.
WewilldiscusstheseinrelationtotheJSCandFFinthecontextofexcitondissociationef-ciency,chargerecombinationandchargetransport.
Itisgener-allyassumedthatsmallerdomainsaremorefavorableforhighexcitondissociationefciency,astheexcitondiffusionlengthistypicallyonlyabout10nm.
[33–35]Also,roughinterfaceswithanincreaseininterfacialareaprovideimprovedexcitondissocia-tionefciency.
However,dependingonthelengthscaleofthisroughness,itmightalsoenhancebi-molecularrecombinationifthechargesarenottransportedefcientlytotheelectrodes.
ThiscompetingeffectwaspreviouslyinvestigatedinbilayermodelsystemsofPFB/F8BTbyYanetal.
[8]Inthatparticularcase,itwasfoundandsupportedbyMonteCarlosimulations,thatsharpinterfacesarebest,andtherecombinationoutweighstheincreaseinarea.
Lastly,domainpurityisimportantasimpuredomainsshouldleadtoenhancedbi-molecularrecom-binationandreducedchargetransport.
Thenthefollowingoverallpictureemerges,asillustratedinFigure6.
DCBleadstodomainsthatarethelargest,withFigure6.
MorphologyevolutionofthePDPP3T/PC71BMblendspreparedbydifferentsolvents.
Adv.
Mater.
2012,24,6335–63416340www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATIONTechnologyofChina,NSFC(Nos.
KGCX2-YW-399+9-1,S2012GR0224,51173189).
R-SoXSandGIWAXSmeasurementsandanalysisbyDr.
WeiMaandProf.
HaraldAdearesupportedbytheUSDepartmentofEnergy,OfceofScience,BasicEnergyScience,DivisionofMaterialsScienceandEngineeringundercontractDE-FG02-98ER45737.
X-raydataisacquiredattheAdvancedLightSource,whichissupportedbythetheDirector,OfceofScience,OfceofBasicEnergySciences,oftheU.
S.
DepartmentofEnergyunderContractNo.
DE-AC02-05CH11231.
Received:July14,2012Revised:August12,2012Publishedonline:September19,2012efcientBHJPSCdeviceswithPDPP3T:PC71BMasactivelayer.
ThePCEofthedevicepreparedbyoptimalconditionreached6.
71%,whichisaremarkableresultforthePSCbasedonDPP-basedpolymers.
Furthermore,themorphologyofthePDPP3T/PC71BMblendlmwassuccessfullyoptimizedbytheapplicationofaDCB/CF/DIO(76:19:5,v/v/v)ternarysol-ventsystemforsolutionprocessingandthereforethePCEofPDPP3T/PCBM-basedPSCdevicescanbeimprovedeffectively.
ByusingAFM,R-SoXSandGIWAXSmeasurements,theevo-lutionofthemorphologyfromthepuresolvent(DCB)tothebinarymixedsolvent(DCB/CF)andthentoternarymixedsol-vent(DCB/CF/DIO)iswelldemonstrated.
Theadvantageofter-narymixedsolventstreatmentisthecombinationoftwostepstuningofmorphology,andhencelong-rangeorderedstructurewithfavorabledomainsizeandgooddomainpurityaswellastherougherdomaininterfacesinthePDPP3T:PC71BMblendcanberealized.
Moreimportantly,thismethodcouldpaveapathtotheopti-mizationofotherhighperformancephotovoltaicmaterials.
FurtheradvancesinefciencycanbeexpectedforthePDPP3T/PCBMsystemwhenthedomainsizecanbefurtherreducedupontheexcitondiffusionlengthof10–20nm.
Thebeststrategyappearstobeuseofathirdco-solventthatpreservestheFF,sharpnessofinterface,andpurityoftheDCB/CFsol-ventmixture,butleadstosmallerdomainstoachievehigherJSC.
EventhoughDIOproducedthebestresults,othersolventadditivesneedtobeexplored.
ExperimentalSectionMaterials:PDPP3T(Mn=780K,PDI=3.
25,GPCmethodbyusingchloroformaseluentat45°C)waspurchasedfromSolarmerMaterialIncandPC71BMwaspurchasedfromNano-CInc.
TheultradrysolventsusedindevicefabricationprocesswerepurchasedfromAlfaAesar.
Theotherchemicalsarecommerciallyavailableproductsandwereusedwithoutanyfurtherpurication.
Measurements:GIWAXS,R-SoXS,andreferencespectroscopymeasurementswereperformedatbeamline7.
3.
3.
,[36]beamline11.
0.
1.
2.
,[37]andbeamline5.
3.
2.
2,respectivelyattheAdvancedLightSource,LawrenceBerkeleyNationalLaboratory,Berkeley,CA.
MorphologywasperformedonaNanoscopeV(Vecco)AtomForceMicroscopyinthetappingmode.
IPCEmeasurementswereperformedatSolarCellSpectralResponseMeasurementSystemQE-R3011(EnliTechnololyCo.
,Ltd.
).
TheJ-Vcurvesweremeasuredunderanilluminationof100mW·cm2AM1.
5GusingaXES-70S1(SAN-EIElectricCo.
,Ltd.
)solarsimulator(AAAgrade,70mm*70mmphoto-beamsize).
2*2cmMonocrystallinesiliconreferencecell(SRC-1000-TC-QZ)waspurchasedfromVLSIStandardsInc.
SupportingInformationSupportingInformationisavailablefromtheWileyOnlineLibraryorfromtheauthor.
AcknowledgementsTheauthorswouldliketoacknowledgethenancialsupportfromNationalhightechnologyresearchanddevelopmentprogram863(2011AA050523),ChineseAcademyofSciences,MinistryofScienceand[1]a)Y.
Huang,X.
Guo,F.
Liu,L.
J.
Huo,Y.
N.
Chen,T.
P.
Russell,C.
C.
Han,Y.
F.
Li,J.
H.
Hou,Adv.
Mater.
2012,24,3383;b)C.
M.
Amb,S.
Chen,K.
R.
Graham,J.
Subbiah,C.
E.
Small,F.
So,J.
R.
Reynolds,J.
Am.
Chem.
Soc.
2011,133,10062;c)S.
C.
Price,A.
C.
Stuart,L.
Q.
Yang,H.
X.
Zhou,W.
You,J.
Am.
Chem.
Soc.
2011,133,4625;d)T.
Y.
Chu,J.
P.
Lu,S.
Beaupre,Y.
G.
Zhang,J.
R.
Pouliot,S.
Wakim,J.
Y.
Zhou,M.
Leclerc,Z.
Li,J.
F.
Ding,Y.
Tao,J.
Am.
Chem.
Soc.
2011,133,4250;e)L.
J.
Huo,S.
Q.
Zhang,X.
Guo,F.
Xu,Y.
F.
Li,J.
H.
Hou,Angew.
Chem.
Int.
Ed.
2011,50,9697.
[2]a)Z.
C.
He,C.
M.
Zhong,X.
Huang,W.
Y.
Wong,H.
B.
Wu,L.
W.
Chen,S.
J.
Su,Y.
Cao,Adv.
Mater.
2011,23,4636;b)L.
T.
Dou,J.
B.
You,J.
Yang,C.
C.
Chen,Y.
J.
He,S.
Murase,T.
Moriarty,K.
Emery,G.
Li,Y.
Yang,Nat.
Photo.
2012,6,180;c)X.
H.
Li,W.
C.
H.
Choy,L.
J.
Huo,F.
X.
Xie,W.
E.
I.
Sha,B.
F.
Ding,X.
Guo,Y.
F.
Li,J.
H.
Hou,J.
B.
You,Y.
Yang,Adv.
Mater.
2012,24,3046;d)C.
E.
Small,S.
Chen,J.
Subbiah,C.
M.
Amb,S.
W.
Tsang,T.
H.
Lai,J.
R.
Reynold,F.
So,Nat.
Photo.
2012,6,115.
[3]L.
M.
Chen,Z.
R.
Hong,G.
Li,Y.
Yang,Adv.
Mater.
2009,21,1434.
[4]B.
A.
Collins,J.
Tumbleston,H.
Ade,J.
Phys.
Chem.
Lett.
2011,2,3135.
[5]B.
A.
Collins,E.
Gann,L.
Guignard,X.
X.
He,C.
R.
McNeill,H.
Ade,J.
Phys.
Chem.
Lett.
2010,1,3160.
[6]B.
A.
Collins,J.
E.
Cochran,H.
Yan,E.
Gann,C.
Hub,R.
Fink,C.
Wang,T.
Schuettfort,C.
R.
McNeill,M.
L.
Chabinyc,H.
Ade,Nat.
Mater.
2012,11,536.
[7]W.
Chen,T.
Xu,F.
He,W.
Wang,C.
Wang,J.
Strzalka,Y.
Liu,J.
G.
Wen,D.
J.
Miller,J.
H.
Chen,K.
L.
Hong,L.
P.
Yu,S.
B.
Darling,NanoLett.
2011,11,3707.
[8]H.
P.
Yan,S.
Swaraj,C.
Wang,I.
Hwang,N.
C.
Greenham,C.
Groves,H.
Ade,C.
R.
McNeill,Adv.
Funct.
Mater.
2010,20,4329.
[9]G.
Li,V.
Shrotriya,J.
S.
Huang,Y.
Yao,T.
Moriarty,K.
Emery,Y.
Yang,Nat.
Mater.
2005,4,864.
[10]G.
Li,Y.
Yao,H.
Yang,V.
Shrotriya,G.
Yang,Y.
Yang,Adv.
Funct.
Mater.
2007,17,1636.
[11]a)F.
Padinger,R.
S.
Rittberger,N.
S.
Sariciftci,Adv.
Funct.
Mater.
2003,13,85;b)W.
L.
Ma,C.
Y.
Yang,X.
Gong,K.
Lee,A.
J.
Heeger,Adv.
Funct.
Mater.
2005,15,1617.
[12]S.
E.
Shaheen,C.
J.
Brabec,N.
S.
Sariciftci,F.
Padinger,T.
Fromherz,J.
C.
Hummelen,Appl.
Phys.
Lett.
2001,78,841.
[13]Y.
Yao,J.
H.
Hou,Z.
Xu,G.
Li,Y.
Yang,Adv.
Funct.
Mater.
2008,18,1783.
[14]J.
K.
Lee,W.
L.
Ma,C.
J.
Brabec,J.
Yuen,J.
S.
Moon,J.
Y.
Kim,K.
Lee,G.
C.
Bazan,A.
J.
Heeger,J.
Am.
Chem.
Soc.
2008,130,3619.
[15]J.
Peet,J.
Y.
Kim,N.
E.
Coates,W.
L.
Ma,D.
Moses,A.
J.
Heeger,G.
C.
Bazan,Nat.
Mater.
2007,6,497.
[16]X.
Guo,C.
H.
Cui,M.
J.
Zhang,L.
J.
Huo,Y.
Huang,J.
H.
Hou,Y.
F.
Li,EnergyEnviron.
Sci.
2012,5,7943.
[17]C.
V.
Hoven,X.
D.
Dang,R.
C.
Cofn,J.
Peet,T.
Q.
Nguyen,G.
C.
Bazan,Adv.
Mater.
2010,22,E63.
[18]F.
L.
Zhang,K.
G.
Jespersen,C.
Bjorstrom,M.
Svensson,M.
R.
Andersson,V.
Sundstrom,K.
Magnusson,E.
Moons,A.
Yartsev,O.
Inganas,Adv.
Funct.
Mater.
2006,16,667.
Adv.
Mater.
2012,24,6335–63416341www.
advmat.
dewww.
MaterialsViews.
comwileyonlinelibrary.
com2012WILEY-VCHVerlagGmbH&Co.
KGaA,WeinheimCOMMUNICATION[28]D.
Peramunage,D.
M.
Pasquariello,K.
M.
Abraham,J.
Electrochem.
Soc.
1995,142,1789.
[29]a)S.
Swaraj,C.
Wang,H.
Yan,B.
Watts,J.
Luning,C.
R.
McNeill,H.
Ade,NanoLett.
2010,10,2863;b)H.
Yan,B.
A.
Collins,E.
Gann,C.
Wang,H.
Ade,C.
R.
McNeill,ACSNano2012,6,677.
[30]B.
A.
Collins,Z.
Li,J.
Tumbleston,E.
Gann,C.
R.
McNeill,H.
Ade,Adv.
Energy.
Mater.
2012,DOI:10.
1002/aenm.
201200377.
[31]H.
Brumberger,ModernAspectsofSmall-AngleScattering.
KluwerAcademicPublishers,Dordrecht,1995,45,463.
[32]G.
Porod,ColloidPolym.
Sci.
1952,125,108–122.
[33]C.
Deibel,V.
Dyakonov,IEEEJ.
SelectedTopicsQuantumElectron.
2010,16,1517–1527.
[34]R.
R.
Lunt,N.
C.
Giebink,A.
A.
Belak,J.
B.
Benziger,S.
R.
Forrest,J.
Appl.
Phys.
2009,105,053711.
[35]P.
E.
Shaw,A.
Ruseckas,I.
D.
W.
Samuel,Adv.
Mater.
2008,20,3516.
[36]A.
Hexemer,W.
Bras,J.
Glossinger,E.
Schaible,E.
Gann,R.
Kirian,A.
MacDowell,M.
Church,B.
Rude,H.
Padmore,J.
Phys.
Conf.
Ser.
2010,247,012007.
[37]E.
Gann,A.
Young,B.
A.
Collins,H.
Yan,J.
Nasiatka,H.
A.
Padmore,H.
Ade,A.
Hexemer,C.
Wang,Rev.
Sci.
Instrum.
2012,83,045110.
[19]F.
Liu,Y.
Gu,C.
Wang,W.
Zhao,D.
Chen,A.
L.
Briseno,T.
P.
Russell,Adv.
Mater.
2012,24,3947.
[20]M.
M.
Wienk,M.
Turbiez,J.
Gilot,R.
A.
J.
Janssen,Adv.
Mater.
2008,20,2556.
[21]J.
C.
Bijleveld,A.
P.
Zoombelt,S.
G.
J.
Mathijssen,M.
M.
Wienk,M.
Turbiez,D.
M.
deLeeuw,R.
A.
J.
Janssen,J.
Am.
Chem.
Soc.
2009,131,16616.
[22]J.
C.
Bijleveld,V.
S.
Gevaerts,D.
DiNuzzo,M.
Turbiez,S.
G.
J.
Math-ijssen,D.
M.
deLeeuw,M.
M.
Wienk,R.
A.
J.
Janssen,Adv.
Mater.
2010,22,E242.
[23]C.
H.
Woo,P.
M.
Beaujuge,T.
W.
Holcombe,O.
P.
Lee,J.
M.
J.
Fréchet,J.
Am.
Chem.
Soc.
2010,132,15547.
[24]H.
Bronstein,Z.
Y.
Chen,R.
S.
Ashraf,W.
M.
Zhang,J.
P.
Du,J.
R.
Durrant,P.
S.
Tuladhar,K.
Song,S.
E.
Watkins,Y.
Geerts,M.
M.
Wienk,R.
A.
J.
Janssen,T.
Anthopoulos,H.
Sirringhaus,M.
Heeney,I.
McCulloch,J.
Am.
Chem.
Soc.
2011,133,3272.
[25]A.
T.
Yiu,P.
M.
Beaujuge,O.
P.
Lee,C.
H.
Woo,M.
F.
Toney,J.
M.
Fréchet,J.
Am.
Chem.
Soc.
2012,134,2180.
[26]L.
T.
Dou,J.
Gao,E.
Richard,J.
B.
You,C.
C.
Chen,K.
C.
Cha,Y.
J.
He,G.
Li,Y.
Yang,J.
Am.
Chem.
Soc.
2012,134,10071.
[27]a)G.
Jones,J.
Chromatogr.
1980,221,27;b)J.
A.
Martinez-Pontevedra,L.
Pensado,M.
C.
Casais,R.
Cela,Anal.
Chim.
Acta.
2004,515,127.
Adv.
Mater.
2012,24,6335–6341