太阳能电池效率提高

SERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).1Advanced surface passivation for silicon wafer solar cellsDrLINFen,DrBramHOEXSolarEnergyResearchInstituteofSingapore(SERIS)WorkshopforSolarCellTesting&FailureAnalysis高效太阳能电池片技术检测和失效分析技术专题研讨会19October2011,Shanghai,ChinaSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).2OutlineIntroductionSurfacepassivationmechanismsSurfacepassivationonc-SiIndustriallyrelevantAl2O3depositiontechniquesApplicationofsurfacepassivationinc-SisolarcellsConclusionsSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).3Introductionp-typec-Sin+ARcoatingAlfrontcontactAlbackcontactBackpassivationHoleElectronIn a good c‐Si solar cell, the entire volume of the cell is electronically activeThus, recombination in the bulk and at bothsurfaces must be minimizedThe electronic quality of the sample is described by its effective carrier lifetimeτeffτfrontτBulkτbackΔnbulkSeff, frontSeff, backbackfrontbulkeffττττ1111++=SERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).4Introduction(cont’d)10100100010121416182022105cm/s1000cm/sFutureTodaySolarcellefficiency(%)Solarcellthickness(μm)10cm/sp-typec-Sin+ARcoatingAlfrontcontactAlbackcontactBackpassivationHoleElectronSeff, backSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).5OutlineIntroductionSurfacepassivationmechanismsSurfacepassivationonc-SiIndustriallyrelevantAl2O3depositiontechniquesApplicationofsurfacepassivationinc-SisolarcellsConclusionsSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).6Fundamentalsofsurfacepassivation__++InterfaceDitSiCBVB__++SiCBVBInterfaceQf++++++ChemicalpassivationChemicalpassivationFieldeffectpassivationFieldeffectpassivationReductionofrecombinationcentersDitReductionofonespeciesnsorpsSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).7•InterfacialoxideispresentbetweenAl2O3andc-Sisubstrate•InterfacialoxidequalityimprovesafterannealandformationofSi-Hisdetected→Chemicalpassivation!01000200030004000AbsorbanceWavenumber(cm-1)Si-OAl-OSi-OC-X/O-HSi-HO-HC-HAsdepositedAfterannealDifferential(x10)2x10-2ChemicalpassivationB.Hoexetal.,J.Appl.Phys.104,113703(2008)SERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).8FieldeffectpassivationSurfacepassivationworksviabothaccumulationandinversionWhenthesurfaceisininversion:•Cross-overofelectronandholedensity•Increasedrecombinationinspacechargeregion(SCR)0100200300400101103105107109101110131015101710192Ωcmp-Si,inthedarkAccumulationCarrierdensity(cm-3)DistancefromFront(nm)ElectronsHoles010020030040010110310510710910111013101510171019ElectronsHolesCarrierdensity(cm-3)DistancefromFront(nm)Inversion2Ωcmp-Si,inthedarkSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).9FieldeffectpassivationMeasure SeffDeposit additional charge on surfaceQeffective= Qf+ Qsurface-10-505101001011021031041/Qeff2NormalizedSeffQeff(1012cm-2)1/Qeff2B.Hoexetal.,J.Appl.Phys.104,113703(2008)051015201101001000QeffectivepositiveSeff(cm/s)Qsurface(1012cm-2)QeffectivenegativeQfin26nmAl2O3film-1.3x1013cm-2SiSERISisaresearchinstituteattheNationalUniversityofSingapore(NUS).SERISissponsoredbytheNationalUniversityofSingapore(NUS)andSingapore’sNationalResearchFoundation(NRF)throughtheSingaporeEconomicDevelopmentBoard(EDB).10-10-505101001011021031041/Qf2NormalizedSeffQf(1012cm-2)1/Qf210810910101011101210131014101510-1100101102103104105106NopassivationNormalizedSeffDit(eV-1cm-2)BestpossibleInterface recombination scales linear with DitInterface recombination scales with 1/Qf2for high positiveand negativeQfMost known interface passivation techniques employ bothfield‐effect and chemical passivatio