CIS CIGS based thin-film solar cells

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1、CIS/CIGSBASEDTHIN-FILMSOLARCELLSMark-DanielGerngroß,JuliaRevereyFacultyofEngineeringUniversityofKielABSTRACT:Thecompoundsemiconductorcopper-indium-gallium-diselenide(CIGS)asthebasismaterialsatisfiestherequirementsofthinfilmsolarcells.CIGSisadirectgapsemiconductorwithhighabsorptivity

2、.ThereforeCIGS-basedsolarcellscanbeproducedmonolithicallyinlargeareathinfilmtechniqueoncheapsubstrates.Theband-gapstructureisacomplexheterojunctionsystem.Thesesolarcellsshowhighefficiencyandverygoodstabilityinoutdoortests.Keywords:CIGS,CIS,thinfilmsolarcell1MATERIALPROPERTIES1.1Gene

3、ralmaterialpropertiesThecrystalstructureofCIS/CIGSisatetragonalchalcopyritestructure,whichisderivedfromthezincblendestructure.[1]Figure2:PseudobinarycutCu2Se-In2Se3ofternaryphasediagram[1]Theb-phase(CuIn3Se5)isadefectphasebuiltbyorderedarraysofdefectpairs(CuvacanciesVCu&InCuantisite

4、s).[1]Figure1:CrystalstructureofchalcopyriteCIGS[4]Thed-phaseisthehightemperaturephase.Itisconstructedbydisorderingthecationsub-lattice(Cu,In),Figure1showsthetetrahedralcoordinationoflatticewhichleadstothezincblendestructure.[1]elements-SeatomshavetwobondstoIn/GaandtwoTheCu2Sephasei

5、ssimilartotheb-phase,beingbondstoCuatoms.EachCuandIn/GaatomhasfourconstructedfromthechalcopyritestructurebyusingCubondstoSeatoms.[1]interstitialsandCuInantisites.[1]Theband-gapofCIGSiscontinuouslyadjustablefrom1.04eVforpureCISto1.68eVforpureCuGaSe2.2IMPURITIESANDDEFECTSAcharacterist

6、icpropertyofCIGSisthehighabsorptivity.About99%oftheincominglightwillbe2.1Impuritiesabsorbedwithinthefirstmicrometerofthematerial.[1]Thea-phaseishighlynarrowedbythea+bandtheTheMinority-carrierlifetime,electrondiffusiona+Cu2SeregionatRT.Bysubstitutionof20-30%ofInlengthandcharge-carrie

7、rmobilitiesarepropertiesthatbyGa,thea-phaseregioniswidenedandtheband-gapdependverymuchonthepreparationconditionsoftheoftheCIGSlayerisadjusted.TheratioofGa/(Ga+In)isthinfilms.Thereforeonlyapproximatedvaluescanbeimportantforthecellperformance.Theoptimalratioisprovided.Theminority-carr

8、ierlifetimeamountst