Advances in thin-film solar cells

305 Pages·2018·10.083 MB·English

by  Dharmadasa, I. M

Advances in
Thin-Film Solar Cells
Second Edition

Advances in
Thin-Film Solar Cells
Second Edition
I. M. Dharmadasa
August14,2018 16:46 PSPBook-9inx6in 00-SolarCell-Prelims
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PanStanfordPublishingPte.Ltd.
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AdvancesinThin-FilmSolarCells(SecondEdition)
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ISBN978-981-4800-12-9(Hardcover)
ISBN978-0-429-00124-6(eBook)
August10,2018 14:9 PSPBook-9inx6in 00-SolarCell-Prelims
Contents
PrefacetotheSecondEdition xiii
ListofSymbolsandAbbreviations xvii
1 PhotovoltaicSolarEnergyConversion 1
1.1 Introduction 1
1.2 PhotovoltaicEffect 3
1.3 SolarEnergyMaterials 3
1.4 ElectronicDevicesUsedforSolarEnergyConversion 5
1.4.1 p–nJunctions 5
1.4.2 p–i–nJunctions 7
1.4.3 Hetero-junctions 8
1.4.4 n–nandp–pJunctions 9
1.4.5 Metal/Semiconductor(orSchottky)Contacts 10
1.4.6 Metal/Insulator/SemiconductorInterfaces 12
1.5 CharacteristicsofaSolarCell 14
1.5.1 I–V CharacteristicsofaSolarCellUnderDark
Conditions 14
1.5.2 I–V CharacteristicsofaSolarCellUnder
IlluminatedConditions 18
1.5.3 HowtoMaximiseV 20
oc
1.5.4 HowtoMaximise J 21
sc
1.5.5 HowtoMaximiseFF 22
1.6 Summary 22
Exercises 24
2 StatusReportonSolarEnergyTechnologies 27
2.1 Introduction 27
2.2 SiSolarCellTechnology 28
2.3 PVManufacturingCostBasedonSiTechnology 32
August10,2018 16:6 PSPBook-9inx6in 00-SolarCell-Prelims
vi Contents
2.4 PVTechnologyBasedonIII–VCompounds 34
2.5 DisruptiveTechnologyforPVDevelopment 35
2.6 EmergingLow-CostThin-FilmTechnologies 36
2.7 Next-GenerationSolarCells 37
2.8 Summary 39
Exercise 41
3 ElectrochemicalDepositionofSolarEnergyMaterials 43
3.1 Introduction 43
3.2 ElectrodepositionofSemiconductors 44
3.3 StrengthsandAdvantagesofElectrodeposition 45
3.3.1 Simplicity,Low-Cost,Scalability,and
Manufacturability 45
3.3.2 Self-PurificationandBuilt-InHydrogen
Passivation 47
3.3.3 ExtrinsicandIntrinsicDoping 48
3.3.4 AbilityinBandgapEngineering 49
3.3.5 OtherAdvantagesofElectrodeposition 49
3.4 ExperimentalEvidence 50
3.4.1 ObservationsinXRD 50
3.4.2 ObservationsinXRF 50
3.4.3 ObservationsinPECCellMeasurements 52
3.4.4 ObservationsinOpticalAbsorption
Measurements 56
3.4.5 ObservationsinPhotoluminescence 57
3.4.6 ImpurityControlinSemiconductors 59
3.5 IssuesinElectrodepositionofSemiconductors 60
3.6 SummaryofElectroplatedMaterialstoDate 63
3.7 ApplicationsinPVDevices 63
3.8 Summary 66
Exercises 69
4 BackgroundoftheCdTeSolarCellandtheNewDevice
Concept 71
4.1 Introduction 71
4.2 ThePreviousModelforaGlass/Conducting
Glass/CdS/CdTe/MetalSolarCell 73
August10,2018 14:9 PSPBook-9inx6in 00-SolarCell-Prelims
Contents vii
4.3 KeyObservationsThatLedtotheFormulationofa
NewModel 76
4.3.1 SurfaceModificationofCdTe 76
4.3.2 EffectsofSurfaceModificationonDefectLevels 76
4.3.3 EffectsofDefectLevelsonElectronicDevices 77
4.3.4 SimilarObservationsonThin-FilmCdS/CdTe
SolarCells 79
4.4 NewConceptforCdS/CdTeSolarCell 80
4.5 DescriptionofExperimentalResultsUsingthe
TwoModels 85
4.5.1 Current–Voltage(I–V)Characteristics 85
4.5.2 Capacitance–Voltage(C–V)Characteristics 86
4.5.3 ElectronBeam–InducedCurrent
Measurements 87
4.5.4 ObservationofDiscreteBarrierHeightsand
V Values 87
oc
4.5.5 AThin-FilmCdTeSolarCellDeviceWithouta
CdSLayer 88
4.5.6 ResultsfromElectricalContactingWork 89
4.5.7 DopingofCdSandCdTeLayers 90
4.5.8 FurtherExperimentalEvidencetoConfirmthe
TrueStructureoftheDevice 91
4.6 PredictionsfortheFurtherDevelopmentofCdS/CdTe
SolarCellsandLatestObservations 94
4.6.1 DopingofWindowandAbsorberMaterials
withn-Dopants 94
4.6.2 ImprovementstoBackContactUsing
MIS-TypeStructures 99
4.6.3 AMulti-layerGradedBandgapApproach 102
4.6.4 DealingwithDefects 103
4.6.5 ProgressduringthePeriod2011–2016 105
4.7 Summary 107
Exercises 111
5 ExtensionoftheNewModeltoCIGSThin-FilmSolarCells 115
5.1 Introduction 115
5.2 SummaryofAccumulatedKnowledgeon
CIGS-BasedMaterials 116
August10,2018 14:9 PSPBook-9inx6in 00-SolarCell-Prelims
viii Contents
5.2.1 DifferentGrowthTechniques 116
5.2.2 Structural,Optical,andElectricalProperties 116
5.2.3 OrderedDefectCompoundLayer 117
5.2.4 LatestDevelopmentsinMaterialsGrowth 117
5.3 SummaryofAccumulatedKnowledgeon
CIGS-BasedSolarCells 118
5.3.1 ConventionalDeviceStructure 118
5.3.2 FrequentlyUsedEnergyBandDiagram 119
5.4 CurrentViewsofthePhysicsBehindCIGSSolarCells 121
5.4.1 p-CIGS/n-CdSHetero-junction 121
5.4.2 p-CIGS/n-CIGSHomo-junction 121
5.4.3 p-CIGS/n-ODCHetero-junction 122
5.5 ReportedDevicePerformance 122
5.6 RecentWorkonMetal/p-CIGSInterfaces 124
5.7 DeeperUnderstandingofMo/CIGS/CdS/i-ZnO/
n-ZnO:Al/Metal-GridSolarCells 126
5.7.1 TypeICIGS-BasedSolarCell 126
5.7.2 TypeIICIGS-BasedSolarCell 130
5.8 DiscussiononFurtherImprovementsofCIGS
SolarCells 132
5.8.1 OptimisationofGrowth,Doping,and
BandgapEngineering 133
5.8.2 DefectLevelIdentificationandEngineering 133
5.8.3 GrowthofCIGSwithControlledOrientation 134
5.8.4 ReplacementofMoUsingTCOforTandem
andDouble-FacedSolarCells 134
5.8.5 FurtherImprovementsoftheDevice
Structure 135
5.9 Conclusions 136
5.10 Summary 138
6 EffectiveHarvestingofPhotons 143
6.1 Introduction 143
6.2 TandemSolarCells 144
6.2.1 ConnectioninSeries 145
6.2.2 ConnectioninParallel 146
6.3 ComparisonoftheTwoConnectingMethods 148
6.3.1 DisadvantagesofSeriesConnections 148
6.3.2 AdvantagesofParallelConnections 149
August10,2018 16:6 PSPBook-9inx6in 00-SolarCell-Prelims
Contents ix
6.4 Conclusions 151
6.5 Summary 152
Exercise 154
7 Multi-layerGradedBandgapSolarCells 155
7.1 Introduction 155
7.1.1 IncorporationoftheImpurityPVEffect 156
7.1.2 IncorporationofImpactIonisation 157
7.2 SummaryofGrowthandProcessDetailsofthe
DeviceStructure 157
7.3 ExperimentalResultsofFullyProcessedDevices 158
7.3.1 ElectricalPropertiesUnderDarkConditions 159
7.3.2 ElectricalPropertiesUnderAM1.5
Illumination 161
7.3.3 IPCEMeasurements 163
7.3.4 EBICMeasurements 164
7.3.5 SIMSProfiling 166
7.3.6 OptimisationofSiDopingConcentration 167
7.4 Discussions 171
7.5 Summary 173
Exercise 175
8 SolarCellsActiveinCompleteDarkness 177
8.1 Introduction 177
8.2 SummaryofExperimentalResults 177
8.3 SearchforExperimentalEvidenceoftheImpurity
PVEffect 179
8.4 ResponsivityMeasurements 180
8.5 I–V MeasurementsUnderDarkConditions 181
8.5.1 I–V asaFunctionofLightIntensity 181
8.5.2 I–V MeasurementsUnderCompleteDarkness 182
8.6 Discussion 184
8.7 Conclusions 186
8.8 Summary 186
Exercise 188
9 EffectsofDefectsonPhotovoltaicSolarCellCharacteristics 189
9.1 Introduction 189
9.2 VariationsofI–V CharacteristicsofMetal/n-CdTe
Interfaces 190