Organic-Inorganic Halide Perovskite Photovoltaics : From Fundamentals to Device Architectures

This book covers fundamentals of organometal perovskite materials and their photovoltaics, including materials preparation and device fabrications. Special emphasis is given to halide perovskites. The opto-electronic properties of perovskite materials and recent progress in perovskite solar cells are described. In addition, comments on the issues to current and future challenges are mentioned. Preface 5 Contents 7 1 Molecular Motion and Dynamic Crystal Structures of Hybrid Halide Perovskites 9 1 Introduction 9 2 Perovskite 9 3 Average Crystal Structure 10 3.1 Orthorhombic Phase (T lessthan 165 K) 12 3.2 Tetragonal Phase (165–327 K) 13 3.3 Cubic Phase (T greaterthan 327 K) 13 3.4 From Methylammonium to Formamidinium 13 4 Molecular Motion 14 5 Ion Transport 17 6 Dielectric Response 19 7 Summary 21 Acknowledgements 22 References 22 2 First-Principles Modeling of Organohalide Thin Films and Interfaces 26 Abstract 26 1 Introduction 26 2 Tin and Lead Perovskites for Establishing a Reliable Computational Protocol 27 3 Importance of the Interfacial Chlorine in TiO2/Organohalide Perovskites Junction 29 4 PbI2-Modified TiO2/MAPbI3 Heterointerface Electronic Coupling 32 5 MAPbI3 Thin Films Deposited on Zinc Oxide—a Thermal Instability Survey 35 6 Defect Migration in MAPbI3 and Its Effect on the MAPbI3/TiO2 Interface 37 7 The MAPbI3/Water Heterogeneous Interface: Hints on Perovskite Degradation by Water 44 References 54 3 Maximum Efficiency and Open-Circuit Voltage of Perovskite Solar Cells 60 Abstract 60 1 Maximum Power-Conversion Efficiency of a Terrestrial Solar Cell 60 1.1 Thermodynamics and Black Body Radiation 60 1.2 Semiconductor-Based Photovoltaics 63 1.3 Radiative Limit of the Open-Circuit Voltage 66 1.4 Shockley–Queisser Limit 69 2 The Bandgap 69 2.1 Absorption Onset and Subgap Urbach Tail 69 2.2 Tuning of the Bandgap and Tandem Devices 71 3 Nonradiative Recombination 73 3.1 Quantum Efficiency of Electroluminescence 73 3.2 Identifying Recombination Mechanisms 75 3.3 Role of the Charge Transport Layers 80 Acknowledgments 81 References 81 4 Defect Physics of CH3NH3PbX3 (X = I, Br, Cl) Perovskites 85 Abstract 85 1 Introduction 86 2 Computational Details 87 3 Results and Discussions 89 3.1 General Trend of Defect Levels in CH3NH3PbX3 Perovskites 90 3.2 Calculated Transition Energies of Intrinsic Point Defects 91 3.3 Calculated Formation Energy of Intrinsic Point Defects 93 3.4 Calculated Surface States 96 3.5 Calculated Grain Boundary States 99 3.6 Doping Properties of CH3NH3PbI3 104 4 Conclusion 108 Acknowledgments 109 References 109 5 Ionic Conductivity of Organic–Inorganic Perovskites: Relevance for Long-Time and Low Frequency Behavior 112 Abstract 112 1 Introduction 112 1.1 Capacitive Anomalies in Perovskite Solar Cells 113 1.1.1 Hysteresis in i-V Sweep Curves 114 1.2 Evidences of Ionic Transport 114 1.2.1 Computational Studies on Defects and Transport 116 1.3 Experimental Elucidation of the Ionic and Electronic Transport Properties 117 2 Methods: D.C. Polarization and A.C. Impedance Spectroscopy 117 3 Electrical Transport Measurements on CH3NH3PbI3 121 3.1 Impedance Spectroscopy 122 3.2 Stoichiometry Polarization 123 3.3 Open-Circuit Voltage Measurements 124 3.4 Identification of the Species Determining the Ionic Conductivity 126 4 Chemical Diffusion Coefficient and Chemical Capacitance 128 4.1 Stoichiometric Polarization and Large Apparent Dielectric Constant 130 4.2 Hysteresis During i-V Sweep 132 4.3 Electrical Circuit Mimicking the Material Behavior 134 5 Concluding Remarks 136 References 137 6 Ion Migration in Hybrid Perovskite Solar Cells 141 1 Introduction 141 2 Ion Migrations in Solid State Materials 144 3 Ion Migration in Organolead Trihalide Perovskite Films 146 3.1 What Is (Are) the Moving Ion(s) in OTP Films 146 3.2 Mobile Ions Formation and Their Migration Channels in Solid Perovskite Film 151 4 Impact of the Ion Migration on Photovoltaic Efficiency and Stability 154 5 Suppressing Ion Migration for Stable OTP Solar Cells 159 6 Conclusions 161 References 162 7 Impedance Characteristics of Hybrid Organometal Halide Perovskite Solar Cells 167 Abstract 167 1 Introduction 167 2 Capacitive Charging and Hysteresis 170 3 Ferroelectric Properties 177 4 Nature of Capacitances in Perovskite Solar Cells: The Dark Capacitances 178 5 Capacitance–Voltage, Doping, Defects and Energy Level Diagram 182 6 Transient Photovoltage and Photocurrent 186 6.1 Open-Circuit Voltage Decay 187 6.2 Transient Current and Charging 189 6.3 Small Perturbation Illumination Methods: Transient Photovoltage and Charge Extraction 191 7 Reactivity and Degradation at Electrodes 193 8 The Light Capacitances 197 9 Conclusion 199 References 199 8 Charge Transport in Organometal Halide Perovskites 204 1 Introduction 204 2 Theoretical Studies on Charge Transport in Hybrid Perovskites 206 3 Charge Carrier Diffusion Length in Hybrid Perovskites 209 4 Charge Carrier Mobility in FET and LED Devices 211 5 The Role of Ion Drift, Polarization, and Traps 214 6 Polaronic Charge Carriers 218 7 Transport in Emerging Perovskite Materials 219 8 Summary and Conclusions 223 References 224 9 APbI3 (A = CH3NH3 and HC(NH2)2) Perovskite Solar Cells: From Sensitization to Planar Heterojunction 226 Abstract 226 1 Introduction 226 2 Optical Properties and Band Structure of CH3NH3PbI3 230 3 Sensitized Perovskite Dots in Liquid Electrolyte 234 3.1 Effect of Precursor Concentration on Photocurrent 234 3.2 Bandgap Tuning by Ethylammonium Cation 234 4 The First Version of Solid-State CH3NH3PbI3 Perovskite Solar Cell 236 5 Controlled Method for Preparing Perovskite Films 239 6 Perovskite Solar Cells Based on Formamidinium Lead Iodide 242 6.1 Adduct Approach for Preparation of HC(NH2)2PbI3 Perovskite Film 242 6.2 Photovoltaic Performance of HC(NH2)2PbI3-Based Perovskite Solar Cell 245 6.3 Stability of HC(NH2)2PbI3 Perovskite 249 7 Summary 253 Acknowledgments 253 References 253 10 Hysteresis Characteristics and Device Stability 257 1 Introduction 257 2 Parameters Affecting Hysteresis 258 2.1 Device Structure and Process Parameters 259 2.2 Measurement and Prior-Measurement Conditions 261 3 Mechanism of Origin to Hysteresis 267 3.1 Ferroelectric Property of Perovskite 268 3.2 Interfacial Carrier Dynamics 270 3.3 Ion Migration 272 3.4 Trap States 275 4 Hysteresis, Stable Power Output and Stability 277 5 Conclusions 281 References 283 11 Perovskite Solar Cells for the Generation of Fuels from Sunlight 287 1 General Introduction 287 1.1 Energy Demand, Global Warming, and the Need for Storage 287 1.2 Solar Fuel Generation and Utilization 288 1.3 Fundamental Principles of Solar-to-Fuels (STF) Conversion 289 1.4 Advantages of Perovskite as Light Harvesters for Solar Fuel Generation 290 2 Perovskite Photovoltaic (PV)-Driven Water Splitting 291 2.1 One Cell-Driven Water Splitting 291 2.2 Water Splitting Driven by Two in Series Connected Perovskite Cells 292 2.3 Two Absorber Tandems Under Serial Illumination for Standalone Water Splitting 294 2.4 Ideal Two Absorber System 298 3 CO2 Reduction 301 3.1 Perovskite PV-Driven CO Generation from CO2 302 4 Discussion and Perspective 304 4.1 System Design and Engineering 304 4.2 Stability Issue and Solution 304 4.3 Perspective 305 References 305 12 Inverted Planar Structure of Perovskite Solar Cells 308 Abstract 308 1 Introduction 308 2 Planar Structure 309 3 Inverted Planar Structure 311 3.1 Film Growth for Improving Efficiency of Inverted Planar Solar Cells 313 3.2 Interface Engineering Hole Transport Layer 314 3.3 Interface Engineering of Electron Transport Layer 316 3.4 Stability of Inverted Structure 317 3.5 Effect of Electron Transport Layer on Stability 318 3.6 Effect of Hole Transport Layer on Stability 320 3.7 Perovskite Materials Stability 320 3.8 Hysteresis in Inverted Planar Solar Cells 320 4 Conclusions and Future Outlooks 322 Acknowledgement 323 References 323 13 Flexible Perovskite Solar Cell 326 Abstract 326 1 Introduction 326 2 Physical Properties of Perovskite Materials for Flexible Devices 328 2.1 Advantages of Perovskite Materials for Plastic Solar Cells 328 2.2 Mechanical Tolerance of Flexible Perovskite Solar Cells 329 3 Recent Progress in Flexible Perovskite Solar Cells 331 3.1 Flexible Perovskite Solar Cells Based on n-i-p Structure 331 3.2 Flexible Perovskite Solar Cells Based on p-i-n Structure 334 3.3 Metal Substrate-Based Flexible Perovskite Solar Cells 335 4 Emerging Technologies for the Commercialization of Flexible Perovskite Solar Cells 336 4.1 Fiber-Shaped Perovskite Solar Cells 336 4.2 Ultralight Flexible Perovskite Solar Cells 337 5 Summary 340 References 340 14 Inorganic Hole-Transporting Materials for Perovskite Solar Cell 343 1 Introduction 343 2 CuI and CuSCN 349 3 Cu2O and CuO 355 4 NiO 356 5 Molybdenum Oxides (MoOx) 358 6 Carbon Materials 359 7 Conclusion 361 References 361 Front Matter....Pages i-viii Molecular Motion and Dynamic Crystal Structures of Hybrid Halide Perovskites....Pages 1-17 First-Principles Modeling of Organohalide Thin Films and Interfaces....Pages 19-52 Maximum Efficiency and Open-Circuit Voltage of Perovskite Solar Cells....Pages 53-77 Defect Physics of CH3NH3PbX3 (X = I, Br, Cl) Perovskites....Pages 79-105 Ionic Conductivity of Organic–Inorganic Perovskites: Relevance for Long-Time and Low Frequency Behavior....Pages 107-135 Ion Migration in Hybrid Perovskite Solar Cells....Pages 137-162 Impedance Characteristics of Hybrid Organometal Halide Perovskite Solar Cells....Pages 163-199 Charge Transport in Organometal Halide Perovskites....Pages 201-222 APbI3 (A = CH3NH3 and HC(NH2)2) Perovskite Solar Cells: From Sensitization to Planar Heterojunction....Pages 223-253 Hysteresis Characteristics and Device Stability....Pages 255-284 Perovskite Solar Cells for the Generation of Fuels from Sunlight....Pages 285-305 Inverted Planar Structure of Perovskite Solar Cells....Pages 307-324 Flexible Perovskite Solar Cell....Pages 325-341 Inorganic Hole-Transporting Materials for Perovskite Solar Cell....Pages 343-366