Semiconductor Materials for Solar Photovoltaic Cells (eBook)

Preface 6
Contents 10
About the Editors 12
Contributors 14
1 3D Geometries: Enabling Optimization Toward the Inherent Limits of Thin-Film Photovoltaics 16
1.1 Introduction 16
1.2 Broader Background 17
1.3 Conflicting Requirements 18
1.4 Optical Modeling and Simulation of 3D Geometries 19
1.5 Nano-/Micro-pillars 20
1.5.1 Advantages of NW Geometry 20
1.5.1.1 Broadband Absorption and Anti-reflection 21
1.5.1.2 Improvement in Charge Separation and Collection 23
1.5.2 Single-Nanowire/Micro-wire Devices 23
1.5.3 3D Absorber Solar Cells 25
1.5.3.1 Chalcogenide Absorbers 25
1.5.3.2 Si Micro- and Nanowires 26
1.5.3.3 Oxides 27
1.6 3D Structures for Light Management 27
1.6.1 Surface Texturing 28
1.6.1.1 Nanocones 28
1.6.1.2 Mei Resonators 29
1.6.2 Plasmonic Structures 30
1.6.2.1 Plasmonic Scattering 30
1.6.2.2 Near-Field Coupling 32
1.6.2.3 Surface Plasmon Polaritons 32
1.7 Back Contact Geometry Devices 33
1.7.1 Back Contact Manufacturing Approaches 34
1.7.2 Back Contact Heterojunction CdS/CdTe Devices 34
1.7.3 Laser Beam-Induced Current Mapping of Device Performance 35
1.8 Summary and Outlook 36
References 36
2 Earth-Abundant Cu2ZnSn(S,Se)4 (CZTSSe) Solar Cells 40
2.1 Introduction 40
2.2 Crystal Structure 42
2.3 Solar Cell Structure 43
2.4 Composition and Phase Diagram 44
2.5 Etching 46
2.6 Defects 47
2.7 Deposition Techniques 49
2.7.1 Vacuum-Based Deposition Methods 50
2.7.1.1 Evaporation 54
2.7.1.2 Sputtering 61
2.7.1.3 Pulsed Laser Deposition (PLD) 65
2.7.2 Non-vacuum Deposition Methods 68
2.7.2.1 Nanocrystal-Based Approach 69
2.7.2.2 Processing of Hydrazine-Based Solution-Particle 74
2.7.2.3 Open-Atmosphere Chemical Vapor Deposition (OACVD) 77
2.7.2.4 Electrodeposition 77
2.7.2.5 Monograin Layer Cell 79
References 81
3 Cu2ZnSnS4, Cu2ZnSnSe4, and Related Materials 90
3.1 History of Cu2ZnSnS4-Related Semiconductors 90
3.1.1 Theoretical Design of I2--II--IV--VI4 Semiconductors 90
3.1.2 Synthesis and Fabrication of Solar Cells 91
3.1.3 Characteristics of Cu2ZnSnS4-Based Solar Cells 93
3.2 Crystal Structure 94
3.2.1 II--VI to I--III--VI2 to I2--II--IV--VI4 Structure Mutation 94
3.2.2 Energetic Stability of Different Quaternary Structures 96
3.2.3 Partial Disorder in Kesterite Structure and Structural Confusion 98
3.3 Electronic Band Structure 99
3.3.1 Band Structure and Band Gap 99
3.3.2 Band Alignment 100
3.3.3 Band Gap Dependence of Cu2ZnSn(S,Se)4 and Cu2Zn(Ge,Sn)Se4 Alloys 102
3.4 Thermodynamic Stability and Secondary Phases 103
3.4.1 Stable Region in Chemical Potential Space 103
3.4.2 Structural Similarity of Secondary Phases 105
3.5 Defect Formation and Ionization 106
3.5.1 Defect Formation Energy 106
3.5.2 Transition Energy Levels 107
3.5.3 Defect and Carrier Concentration 110
3.6 Surfaces 111
3.6.1 Surface Reconstruction 111
3.6.2 Electronic States of Surfaces 112
Acknowledgements 114
References 114
4 ZnO Doping and Defect Engineering---A Review 119
4.1 Introduction 119
4.2 n-type Doping 121
4.2.1 Intrinsic n-type Conduction 121
4.2.2 Intentional n-type Doping 121
4.3 p-type Doping 121
4.3.1 Group I p-type Doping 122
4.3.2 Group V p-type Doping 124
4.3.2.1 Nitrogen Doping 124
4.3.2.2 Phosphorus Doping 130
4.3.2.3 Arsenic Doping 136
4.3.2.4 Antimony Doping 138
4.3.2.5 Bismuth Doping 140
4.3.3 Group IB p-type Doping 141
4.3.4 Codoping 142
4.3.4.1 Ga-N Codoping 142
4.3.4.2 Al--N Codoping 143
4.3.4.3 In--N Codoping 143
4.3.4.4 Other Codoping 143
4.3.4.5 Dual Acceptor Codoping 144
4.3.5 Intrinsic p-type ZnO 145
4.4 Conclusion 145
Acknowledgements 146
References 146
5 Hydrogen Production and Photodegradation at TiO2/Metal/CdS Sandwich Using UV--Visible Light 155
5.1 Introduction 155
5.2 Experimental Section 157
5.2.1 TiO2 Synthesis 157
5.2.2 Pt, Ag, and Au Deposition 158
5.2.3 CdS Deposition 158
5.2.4 Synthesis of CdS--Au--TiO2 Sandwich Nanorod Array 158
5.2.5 Techniques Used for the Characterization of the Composites 159
5.2.6 Film Preparation and Measurements 159
5.2.7 Photocatalytic Measurements 159
5.2.8 Actinometry Measurements 160
5.3 Results 160
5.3.1 Surface and Photoelectrochemical Characterization 160
5.3.1.1 Scanning Electron Microscopy 160
5.3.1.2 XRD and EDS Analyses 162
5.3.1.3 Diffuse Reflectance 163
5.3.1.4 Transmission Electron Microscopy (TEM) 164
5.3.1.5 Photoelectrochemical Analysis 165
5.3.2 Photocatalytic Hydrogen Generation 166
5.3.2.1 Photocatalytic Hydrogen Generation with Polysulfide as the Sacrificial Agent 166
Effects of PGM in IH-TiO2/M/CdS (M = Pt, Ag, Au) Photocatalysis 166
Comparison of the Pt-Based Catalysts on Photocatalytic Hydrogen Evolution in DI Water 167
Comparison of the Pt-Based Catalysts on Photocatalytic Hydrogen Evolution in Aqueous Na2S/Na2SO3 168
5.3.2.2 Photocatalytic Hydrogen Generation with Methyl Orange as the Sacrificial Agent 169
Need for Replacing Stabilizers with Pollutants 169
Photocatalytic Hydrogen Generation in the Presence of MO 169
Estimation of the Kinetic Parameters 170
5.3.3 CdS--Au--TiO2 Sandwich Nanorod Array Enhanced with Au Nanoparticle as Electron Relay and Plasmonic Photosensitizer 172
5.3.4 Dual Role of Au Nanoparticle 174
5.4 Discussions 175
5.4.1 Pt, Au, and Ag Noble Metal Ad-Atoms 175
5.4.2 Mechanism of the Photocatalytic Hydrogen Generation 176
5.4.3 Comparison of the Photocatalytic Hydrogen Generation with Other Reported Systems 176
5.4.4 Photocatalytic Hydrogen Generation with CdS--Au--TiO2 177
5.5 Conclusion 178
Acknowledgements 178
References 179
6 Organic Photovoltaics 182
6.1 Introduction to Organic Photovoltaics 182
6.2 OPV Materials 186
6.2.1 Solution-Processable OPV Materials 186
6.2.1.1 Solution-Processable Electron Donors 186
6.2.1.2 Solution-Processable Electron Acceptors 192
6.2.2 Vacuum-Deposited Materials 194
6.3 Materials Structure in OPV 196
6.3.1 Order: Local and Long Range 197
6.3.2 Nanoscale Structure 199
6.4 The Outlook for OPV 200
References 202
7 Nanophase Engineering of Organic Semiconductor-Based Solar Cells 210
7.1 Introduction 210
7.2 Synthesis of Conjugated Molecules for High-Efficiency Organic Photovoltaics 212
7.2.1 Donors 213
7.2.2 Acceptors 214
7.3 Optimizing Film Morphology and Phase Separation in Polymer Photovoltaics 216
7.3.1 Thermal Annealing 216
7.3.2 Solvent Annealing 218
7.3.3 Processing Additives 219
7.3.4 Compatibilizers 222
7.3.5 Layer-by-Layer Processing for Optimized Film Morphology and Reduced Charge Recombination 225
7.3.6 Isotopic Effects of Deuteration on Film Morphology, Phase Separation, and Optoelectronic Properties of Conducting Polymers 226
7.4 Tailoring the Structure and Orientation of Conjugated Molecular at Interface for High-Performance Photovoltaics 230
7.4.1 Interfacial Control at the Interfaces Between the Active Layer and Electrodes 230
7.4.2 Interfacial Control at the Interfaces Between the Donor and the Acceptor 231
7.4.3 Understanding Substrate-Assisted Alignment and Assembly of Conjugated Molecules for Organic Photovoltaics 234
7.5 Summary 236
Acknowledgement 237
References 237
8 Solar Cell Characterization 242
8.1 Introduction 242
8.2 I--V Curves: Features and Uses 243
8.3 Solar Simulator Performance 245
8.4 Spectral Irradiance Measurements 247
8.5 Spectral Response Measurements of Solar Cells 248
8.6 Spectral Mismatch Factor 252
8.7 Measuring I--V Curves 253
8.8 Additional Remarks 256
8.9 Summary 257
References 257
9 Applications 259
9.1 Introduction 259
9.2 Early Applications in Space Engineering 261
9.3 Terrestrial Application 262
9.3.1 PV Power Stations 262
9.3.2 Conventional BIPV 263
9.3.3 Hybrid BIPV 263
9.3.4 Semitransparent Solar Panel 266
9.4 Power Source for Electrical Facilities 267
9.4.1 Solar Vehicles 267
9.4.2 Solar Power for Other Electrical Device/Equipment 268
9.5 Solar Cell Efficiency, Life, and Cost 269
9.5.1 Laboratory Efficiency Versus Production Efficiency 270
9.5.2 Efficiency Versus Temperature 270
9.5.3 Service Life 271
9.5.4 Cost 272
9.6 Solar Industry and Market 272
9.6.1 Solar Industry 273
9.6.2 Solar Market 275
9.6.2.1 PV Market Growth 275
9.6.3 PV Market Driver 282
9.7 Summary 283
Acknowledgements 283
References 284
Index 288