Refined optoelectronic properties of silicon nanowires for improving photovoltaic properties of crystalline solar cells a simulation study

TOPICAL REVIEW OPEN ACCESS Emerging inorganic solar cell efficiency tables version 2 To cite this article Andriy Zakutayev et al 2021 J. Phys. Energy 3 032003 View the article online for updates and enhancements. This content was downloaded from IP address 123.139.57.166 on 28/06/2021 at 1204 J. Phys. Energy 3 2021032003 https//doi.org/10.1088/2515-7655/abebca Journal of Physics Energy OPEN ACCESS RECEIVED 22October2020 REVISED 27January2021 ACCEPTED FOR PUBLICATION 3March2021 PUBLISHED 16April2021 Originalcontentfrom thisworkmaybeused underthetermsofthe CreativeCommons Attribution4.0licence . Anyfurtherdistribution ofthisworkmust maintainattributionto theauthorsandthetitle ofthework,journal citationandDOI. TOPICAL REVIEW Emerging inorganic solar cell efficiency tables version 2 Andriy Zakutayev 1, Jonathan D Major2 , Xiaojing Hao3 , Aron Walsh4 ,5, Jiang Tang6 , Teodor K Todorov 7 , Lydia H Wong 8and Edgardo Saucedo9 ,∗ 1 NationalRenewableEnergyLaboratoryNREL,Golden,CO80401,UnitedStatesofAmerica 2 StephensonInstituteforRenewableEnergy,DepartmentofPhysics,UniversityofLiverpoolUL,LiverpoolL697ZF,UnitedKingdom 3 AustralianCentreforAdvancedPhotovoltaics,SchoolofPhotovoltaicandRenewableEnergyEngineering,UniversityofNewSouth WalesUNSW,Sydney,NSW2052,Australia 4 DepartmentofMaterials,ImperialCollegeLondonICL,ExhibitionRoad,LondonSW72AZ,UnitedKingdom 5 YonseiUniversityYU,Seoul03722,RepublicofKorea 6 WuhanNationalLaboratoryforOptoelectronics,HuazhongUniversityofScienceandTechnologyHUST,430074Wuhan,People’s RepublicofChina 7 IBMThomasJ.WatsonResearchCenter,YorktownHeights,NewYork10598,UnitedStatesofAmerica 8 SchoolofMaterialsScience HZB, Ge rman y [32 ]. Spin co ating of 2-me tho xy ethanol base d sol utio n. Cu 2ZnS n0.78 Ge 0.22 Se 4 12.3 0.527 32.2 72.7 0.519 1.11 Glass/M o/CZT GT Se/CdS/ ZnO/AZ O/A g/AR C EQE, in-house AIST ,Jap an [33 ].C o-e vap orat ion and rea cti ve annealing . Li 0.06 Cu 0.94 2ZnS nS,S e4 11.6 0.531 33.7 64.8 0.285 1.13 Glass/S iO x/M o/LiCZT SS e/ CdS/ZnO/AZ O/N i/A l/MgF 2 EQE, in-house EMP A,S witz erland; Uni ver sidad Autnoma de Madr id, Sp ain; HZB, Ge rman y[ 34 ].Spin co ating of DMSO base dsol utio n. Cu 2Zn 0.95 Mn 0.05 SnS,S e4 8.9 0.418 33.7 63.3 0.34 1.06 Glass/M o/CMZT SS e/CdS/ ZnO/AZ O/N i/A l EQE Nankai Uni ver sity ,China; Nat ional Inst itut eo fM ate rial Scie nce, Jap an [35 ]. Spin co ating of 2-me tho xy ethanol base d sol utio n. Cu 2Zn 0.96 Mg 0.04 SnS,S e4 7.2 0.419 37.2 46.5 0.3 1.01 Glass/S iO x/M o/CZMT SS e/ CdS/i-ZnO/AZ O/N i/ Al/MgF2 Uni ver sidad Autnoma de Madr id, Sp ain [36 ].P recur sor sol utio np repar ed by dime thy lsulf oxid eDMSO. C ont inue d 7 J. Phys. Energy 3 2021032003 AZakutayevet al Tab le 2. C ont inue d. Mat erial Eff. VO C V JSC mA cm − 2 FF Ar ea cm 2 Eg eV De vic est ruc tur e Means of ver ificat ion Inst itu tio ns and Co mme nts Cu 2S nS 3 5.1 0.290 34.5 51.3 0.3 0.95 Glass/M o/CT S/CdS/ i-ZnO/AZ O/N i/A l EQE, in-house Rits ume ikan Uni ver sity ,Jap an [37 ]. Abso rbe rp repar ed by Spu tte ring of Cu-S nS2 co mp ound, and e-b eam evap orat ion of NaF . Cu 2ZnS n0.91 I0.09 S,S e4 7.19 0.393 32.12 56.96 0.21 1.075 Mo-f oil/CZTISS e/CdS/ i-ZnO/IT O/A g EQE, in house Fujian JIangx ia Uni ver sity ,Fuzho u,China [38 ].A bso rbe ris de posit ed on fle xib le Mo foil by spin co ating of pre cur sor sol utio n base do n1,2-e thane dithiol edtH2 and 1,2-e thy lene diamine en sol utio n. Cu 2ZnS nx Ga 1− xS,S e4 10.8 0.455 36.48 65.05 0.21 1.162 Glass/M o/CZT GSS e/CdS/ iZnO/IT O/A g/MgF 2 EQE, in house He nan Uni ver sity [31 ].W ith AR C; thin film isd ep osit ed by spin co ating of pre cur sor sol utio nbase do ne thy lendiamine and 1,2 ethane dithiol. Cu 2S n1− xGe xS 3 6.73 0.442 26.6 57.1 0.17 1.09 Glass/M o/CT GS/CdS/ ZnOGa/A l EQE, in-house To yota Ce ntr al Res ear ch PCp htalo cyanine. 11 J. Phys. Energy 3 2021032003 AZakutayevet al well-establishedsolarcelltechnologies.However,fortheemergingsolarcelltechnologiesthataredeveloping veryquickly,suchcertificationisnotalwayspractical,soonlyin-housemeasuredphotovoltaicPV efficienciesareoftenreported.Thus,itisimportanttoreviewherecommonbestpracticesforin-housesolar cellefficiencymeasurements.Themostbasicrequirementsforlab-basedsolarcellefficiencymeasurements include a usingtheairmass1.5spectrumAM1.5forterrestrialcellsbychoosingthehighest-qualitysolarsimu- latoravailable; b applyingone-sunofilluminationwithintensityof1000Wcm −2 byadjustingthecell/simulatordistance tomatchtheexpectedcurrentofthereferencecell; c controllingcelltemperatureduringthemeasurementto25 ◦Cusingactivecoolingorheating; d usingfour-pointprobegeometrytoremovetheeffectofprobe/cellcontactresistance. Inaddition,thereareseveralotherbestpracticestofollow. a Areasofthemeasuredsolarcellshavetobecarefullydefinedusingdeviceisolationand/orlightmasking; thisisparticularlyrelevanttoabsorberswithlargecarrierdiffusionlengths. b Currentdensity–voltagemeasurementshavetobeperformedinbothforwardandreversedirections, whichisespeciallyimportantforemergingabsorberswithtendencyforhysteresis. c EQEmeasurementhastobereportedtoassistwithspectralcorrection,andintegratedwiththeAM1.5 referencespectrumtoobtainthecurrent,tobecomparedtoreportedJsc. d Statisticalanalysisresults,includingthenumberofthesolarcellsmeasured,andthemeanvalueshaveto bementioned. e Short-timeevolutionofthereporteddeficiencyhastobeverifiedatthemaximumpowerpointorwith thephotocurrentatmaximumpowerpoint. f Long-timestabilityanalysisisencouraged,underlightandelectricalbias,withmeasuredtemperature andhumidity. g Formulti-junctionsolarcells,theilluminationbiasandvoltagebiasusedforeachcellhavetobereported. Finally,wereemphasizethatthesearejustguidelinesforin-housesolarcellmeasurements,whenexternal certificationisnotpractical.However,researchersworkingonemergingsolarcelltechnologiesarestrongly encouragedtostrivetowardsperfectionandconsidersubmissionoftheirdevicestooneofthe internationallyrecognizedinstitutions. 2.Efficiencytables Table1 presentsthelistofmaterialsthathavebeenidentifiedfortheauthorsascertifiedsolarcells,andare consideredasthehighestreportedconversionefficiencyintheirclassoftechnology.Thelastpartoftable1 collectsthetechnologiesthatbeingcertified,donotfulfilsomeofthecriteriausedforincludingtheminthe principalsection.Table2 containsthelistofmaterialsanddeviceperformancefornon-certifiedsolarcells. Thecombineddatafrombothtablesisplottedinfigure2 ,whereitisseparatedintothreecategoriesmetal pnictidese.g.ZnSnP2 ,chalcogenidese.g.PbS,andhalidese.g.BiI3 . 3.Newentries 3.1.Oxides Therehavebeennonewrecordsreportedforsolarcellswithoxideabsorbers,butseveralimportantadvances havebeenmade.ForCu2 OabsorberswithGa2 O3 bufferlayersgrownbychemicalvapourdeposition,the Vocof1.78Vhasbeenachievedalbeitwithsmallphotocurrentof2mAcm −2 [65 ].Thisdemonstratesthe abilityofCu2 Otoreach80of VocentitlementbasedonShockley–QueisserlimitEg 2.2eV,and achieveinthefuture13efficiencyforthickerabsorberlayersbasedonnumericalmodels[ 66 ].Alow damagemagnetronsputteringmethodforfabricationofZnOcontactstoCu2 Osolarcellshasbeenalso recentlydemonstrated[67 ].TheprogressinCu2 Oandotheroxidesolarcellshasbeensummarizedina recentroadmaparticle[67 ]andabookchapter[68 ]. Asofthemoreexoticoxideabsorberswithperovskitestructureandferroelectricproperties,upto4.2 efficiencyhasbeenreportedinmixed-phaseBiMnO3 andBiMn2 O5 thinfilmabsorbers[18 ].Thereported Vocof1.5V, Jscof7mAcm −2 andfillfactorof0.58havebeenreportedtable 2 .Thisreportcomesfromthe samegroupthatpublishedon3.3efficiencyinsinglelayersand8.1inmultilayersofBi 2 FeCrO6 6years ago[41 ].Neitheroftheseexcitingresultspublishedhighprofilejournalshavebeenreplicatedbyother 12 J. Phys. Energy 3 2021032003 AZakutayevet al Figure2. Efficiencya,Vocb,JsccandFFdofthemostrelevantthinfilminorganicPVtechnologies,fromtables1 and2 . TheirperformanceiscomparedtothefullShockley–QueisserSQlimitfortheAM1.5spectrumsolidgreylineand50ofthe SQlimitdashedgreyline. groups,whichissomewhatconcerning.TheprogressinBiFeO3 derivatives[69 ]andotherperovskitesas photoferroicmaterialshasbeenrecentlyreviewed[70 ]. 3.2.Chalcogenides Fivenewresultsarereportedinthepresentversionforchalcogenides,withtwonewresultsfromkesterite andantimonychalcogeniderespectively,andthreenewentriesfromkesterite.Thefirstnewresultis12.5 efficiencypureselenidekesteriteCu2 ZnSnSe4 solarcellfabricatedonglassshownintable1 .Thishighest efficiencypureselenideCZTSesolarcellalsodemonstratesthesmallestVoc-deficitgivenbyEg/q−Vocof anyreportedkesteritefamilydevices.Thereportedefficiencyimprovementisrealizedbyengineeringthe localchemicalenvironmenti.e.properchemicalcompositionandcompleteoxidationofSntoSn4 during thegrowthofkesteritethin-film,particularlyatthepointintimewhentheformationofkesteriteinitiates. Withthisdefectcontrolmethod,thereportedelectricalpropertiesi.e.mobility,carrierconcentrationof kesteriteareimprovedandthedetrimentalintrinsicdefectsaresuppressed.Oneofthreenewentriesfor kesteriteintable2 isthemagnesium-alloyedkesterite.TheintroductionofsmallamountofMgintokesterite resultsinthe7.2efficiencyCu 2 Zn0.96 Mg0.04 SnS,Se4 solarcells.SuchsmallamountMgcanleadtothe changeinlatticeconstantandcarrierconcentrationofkesterite,whichseemstoplayasimilarroletoalkaline Lithium.NotablesubstitutionofgroupIIIelementsofInandGainCu2 ZnSnS,Se4 werealsoreportedto improvetheefficiencyeventhoughthereasonsforimprovementsarenotthoroughlyinvestigated[31 ]. Cd-substitutedCZTSisrecentlyreportedwithanewrecordof12.6[ 30 ]byengineeringthecharge extractionlayers.Wealsonotethatasignificantnumbersofgroupshavereportedefficienciesexceeding12 [8 ,30 ,71 ]andclosingthegapwithworldrecordefficiencyreportedbyIBMin2013[ 6 ].Mostofthese reports,however,havenotcompletelyeliminatedtheoriginofthedeepdefectswhicharewidelybelievedto causebandtailingandthesignificantVocdeficitinthisclassofmaterials.Recenttheoreticalanalysisand experimentalevidenceseemtoindicatethatamajorcontributiontothebandtailsisfromthedeep 2Cu Zn SnZndefectclusters[72 ,73 ].ThelatestexperimentalevidenceisdemonstratedintheCu2 CdZnS4 CCTSwhereCdsubstitutionofZninCu-poorCCTSsuppressthedeleterious2Cu Zn SnZndefectclusters andsignificantlyreducesbandgapfluctuations[21 ].ThisworksetsanewefficiencyrecordinCu2 CdZnS4 with7.96,whichisthehighestefficiencyamongthenovelcompoundsderivedfromCu–Zn–S/Se. 13 J. Phys. Energy 3 2021032003 AZakutayevet al Anothertwonewentriesintable2 arefromsimplechalcogenides,i.e.5.1efficiencyCu 2 SnS3 and6.73 efficiencyGe-alloyedCu2 SnS3 .NotablethatSn/GegradientisrealizedinthelatterCu2 Sn1 −xGexS3 CTGS. 3.3.Pnictides TherehavebeenseveralrecentreportsonZnSnP2 basedsolarcells[74 ].Thehighest3.4efficiencyreported todateisforZnSnP2 singlecrystalabsorberswithCd,ZnSbufferlayers[17 ],withJscof12mAcm −2 ,Voc of0.47andafillfactorof0.59table 2 .ThinfilmZnSnP2 solarcellwithCdSbufferlayerspreparedby phosphidationofZn/Snstackshadmuchlowerefficiencies0.02[ 75 ]comparedtocrystalbased ZnSnP2/CdSsolarcells2[ 76 ].All-phosphideZnSnP2 singlecrystaldeviceswithCdSnP2 bufferlayers showedclearrectificationbehaviourbutnophotoresponse[77 ]. 3.4.Halides ThenumberofpublishedpapersreportinghalidematerialsforPVmainlyperovskitehalides,areincreasing quickly,andinconsequenceseveralprogresseshavebeenreported.Mostofthehighefficiencyabsorbers becomesfromtheCs–Pbperovskitehalidefamily,andhaveshown1–3recordefficiencyimprovementin thelastyear.Someoftheseprogressesarerelatedtotheuseofadditivesforthebestcontrolofgrowth procedureandcrystallizationprocess. CsPbI3 therecordefficiencyhasimproveduptoanimpressive19.03.Wang et al[47 ]demonstrated thattheuseofDMAIisveryeffectivetomanipulatethecrystallizationprocessofCsPbI3 ,confirmingthatthe DMAIadditivewouldnotalloyintothecrystallatticeofCsPbI3 perovskite.Furthermore,theuseof phenyltrimethylammoniumchloridepassivatedCsPbI3 inorganicperovskite,allowingfortheimpressive efficiencyimprovement,althoughthereisadebateifDMAandDMAIcansitattheA-sitesoftheperovskite structureandthesematerialsarenon-fullyinorganic. CsPbBr3 althoughmoremodest,CsPbBr3 hasachievedanewrecordof10.91.Todoso,Tong et al [46 ]developedagrowthprocedureinducedbyphasetransitionthatmakesthegrainsizeofperovskitefilms moreuniform,andalsolowersthesurfacepotentialbarrierthatexistsbetweenthecrystalsandgrain boundaries. CsPbBrI2 andCsPbIBr2 inthefirstcaseonlylimitedefficiencyimprovementhasbeenreportedinthe lastmonths,achieving16.79efficiencyrecordwithandimpressive Vocof1.32V.Thisimprovementwas againrelatedtopassivationeffectandn-typedopingbyintroducingCaCl2 ,observingalsothatthe crystallinityoftheCsPbI2 Brperovskitefilmwasenhanced,andthetrapdensitywassuppressedthroughthe useofCaCl2 treatment[48 ].Inthesecondcase,arecordefficiencyof11.10hasbeenreportedwithan improvedVocof1.21V,butwithalargeenhancementoftheFFupto74.82[ 49 ].Thishasbeenpossible thankstotheintroductionofaLewisbasePEGasadditiveobservingsuppressednon-radiative electron–holerecombinationandafavourableenergybandstructure. Otherhalideperovskitesdonotreportimportantprogressesintermsofconversionefficiencyinthelast months. 3.5.Mixed-anion Startingfromthissecondeditionoftheefficiencytables,weareincludinganewclassofPVabsorbersbased onmixedantimonyand/orbismuthchalcogenide-halides.SpecialmentionmeritstheworkofNeoandSeok [55 ],whereusingafastvapourprocesstheydevelopedSbSIandSbSI-interlayeredSb2 S3 solarcells, demonstratingaTiO2 /Sb2 S3 /SbSI/HTMdevicewithaconversionefficiencyof6.08.Efficienciesbetween 1and4havebeenalsoreportedforSbSI,Sb,BiSIandBiSIsystems,demonstratingthelargepotential ofthesemixedchalcogenide-halidecompoundsandtheincreasedinterestthatthescientificcommunityis puttinginsuchmaterialsforsolarcellsapplications. 4.LatestprogressesinselectedtopicQ-1DabsorbersforPV Traditionally,absorbermaterialsforPVsarelimitedtosemiconductorswiththree-dimensional3Dcrystal structurei.e.GaAs,CdTeandCuIn,GaSe2 thusenjoyingthenearlyisotropicfilmgrowthandcarrier transport.Recently,thepreviouslyabandonedlow-dimensionalabsorbermaterialshaveattractedwide attentionbecauseoftheirsimpleandEarth-abundantcomposition,andperformanceimprovement [4 ,60 ,78 ].Specifically,theQ-1Dbinaryantimony-basedchalcogenideSb 2 S3 ,Sb2 Se3 andSb2 S,Se3 alloy solarcellsarenontoxicandstable,andhaveachievedimpressivepowerconversionefficiencyof7–10 [4 ,12 ,79 ].Q-1DSb-basedchalcogenidesaremadeupofcovalentlybonded[Sb 4 Se6 ]n ribbons,andthese ribbonsarestackedviaweakVanderWaalsforcealonga-andb-axis[80 ].Basedondeviceconfiguration, Q-1DSb-basedchalcogenidesolarcellscanbedividedintosensitizedsolarcellsandplanarsuperstrateand 14 J. Phys. Energy 3 2021032003 AZakutayevet al substratedevices.Next,wewillbrieflyreviewthemainefficiencyimprovementofQ-1Dsolarcellsineach configuration Sensitized-typesolarcell.Attheearlyage,Sb-basedchalcogenidesensitized-typesolarcellswasledby SeokgroupfromKoreaResearchInstituteofChemic