Thin Film Solar Cells

Jef Poortmans and Vladimir Arkhipov are the authors of Thin Film Solar Cells: Fabrication, Characterization and Applications, published by Wiley.

• Series Preface xiiiPreface xv1 Epitaxial Thin Film Crystalline Silicon Solar Cells on Low Cost Silicon Carriers 1Jef Poortmans1.1 Introduction 11.2 Deposition Technologies 41.2.1 Thermally Assisted Chemical Vapor Deposition 51.2.2 Liquid Phase Epitaxy – Electrodeposition 61.2.3 Close Space Vapor Transport Technique 81.2.4 Ion Assisted Deposition 91.2.5 Low Energy Plasma Enhanced Chemical Vapor Deposition/Electron Cyclotron Resonance Chemical Vapor Deposition 101.3 Silicon Based Epitaxial Layer Structures for Increased Absorbance 111.3.1 Epitaxial Growth on Textured Substrates 111.3.2 Silicon–Germanium Alloys 121.3.3 Germanium–Silicon Structures 151.3.4 Epitaxial Layers on a Buried Backside Reflector 171.4 Epitaxial Solar Cell Results and Analysis 211.4.1 Laboratory Type Epitaxial Solar Cells 211.4.2 Industrial Epitaxial Solar Cells 221.4.3 Special Epitaxial Solar Cell Structures 241.5 High Throughput Silicon Deposition 241.5.1 Chemical Vapor Deposition Reactor Upscaling 251.5.2 Liquid Phase Epitaxy Reactor Upscaling 291.6 Conclusions 32References 322 Crystalline Silicon Thin Film Solar Cells on Foreign Substrates by High Temperature Deposition and Recrystallization 39Stefan Reber, Thomas Kieliba, Sandra Bau2.1 Motivation and Introduction to Solar Cell Concept 392.2 Substrate and Intermediate Layer 422.2.1 Substrate 422.2.2 Intermediate Layer 442.3 Zone Melting Recrystallization 482.3.1 Introduction 482.3.2 Zone Melting Recrystallization Film Growth 512.3.3 Features of Silicon Layers Recrystallized by Zone Melting Recrystallization 532.3.4 Development of Lamp Heated Zone Melting Recrystallization Processors 592.3.5 Zone Melting Recrystallization on Ceramic Substrates 642.4 Silicon Deposition 662.4.1 Requirements of Silicon Deposition for Photovoltaics 672.4.2 Some Basics on Thermal Silicon Atmospheric Pressure Chemical Vapor Deposition from Chlorosilanes 682.4.3 R&D Trends in Silicon Atmospheric Pressure Chemical Vapor Deposition for Photovoltaics 712.4.4 Silicon Chemical Vapor Deposition on Ceramic Substrates 732.5 Solar Cells on Foreign Substrates 752.5.1 Options for Solar Cell Fabrication 762.5.2 Solar Cells on Model Substrates 782.5.3 Solar Cells on Low Cost Substrates 822.6 Summary and Outlook 85Acknowledgments 87References 873 Thin Film Polycrystalline Silicon Solar Cells 97Guy Beaucarne, Abdellilah Slaoui3.1 Introduction 973.1.1 Definition 973.1.2 Why Polycrystalline Thin Film Silicon Solar Cells? 983.2 Potential of Polysilicon Solar Cells 983.2.1 Light Confinement 983.2.2 Diffusion Length 993.2.3 Modeling 1003.3 Substrates for Polysilicon Cells 1013.4 Film Formation 1033.4.1 Initial Step for Grain Size Enhancement 1033.4.2 Techniques for Active Layer Formation 1063.4.3 Defect Density and Activity 1123.5 Solar Cell and Module Processing 1153.5.1 Device Structure 1153.5.2 Junction Formation 1173.5.3 Defect Passivation 1183.5.4 Isolation and Interconnection 1183.6 Polysilicon Solar Cell Technologies 1203.6.1 Solid Phase Crystallization Heterojunction with Intrinsic Thin Layer Solar Cells 1203.6.2 Surface Texture and Enhanced Absorption with Back Reflector Solar Cells 1213.6.3 Crystalline Silicon on Glass Technology 1213.6.4 Other Research Efforts Around the World 1223.7 Conclusion 123References 1234 Advances in Microcrystalline Silicon Solar Cell Technologies 133Evelyne Vallat-Sauvain, Arvind Shah and Julien Bailat4.1 Introduction 1334.2 Microcrystalline Silicon: Material Fabrication and Characterization 1344.2.1 Microcrystalline Silicon Deposition Techniques 1344.2.2 Undoped Microcrystalline Layers 1374.2.3 Doped Layers 1474.3 Microcrystalline Silicon Solar Cells 1484.3.1 Light Management Issues 1494.3.2 Single Junction Microcrystalline Silicon Solar Cells 1544.3.3 Tandem Amorphous/Microcrystalline Silicon Solar Cells: The Micromorph Concept 1594.4 Conclusions 163References 1655 Advanced Amorphous Silicon Solar Cell Technologies 173Miro Zeman5.1 Introduction 1735.2 Overview of Amorphous Silicon Solar Cell Technology Development and Current Issues 1745.2.1 1970s 1745.2.2 1980s 1745.2.3 1990s 1745.2.4 After 2000 1755.2.5 Current Technology Issues 1755.3 Hydrogenated Amorphous Silicon 1775.3.1 Atomic Structure 1775.3.2 Density of States 1795.3.3 Models for the Density of States and Recombination–Generation Statistics 1805.3.4 Optical Properties 1815.3.5 Electrical Properties 1835.3.6 Determination of Density of States 1875.3.7 Metastability 1905.3.8 Hydrogenated Amorphous Silicon from Hydrogen Diluted Silane 1925.3.9 Doping of Hydrogenated Amorphous Silicon 1945.3.10 Alloying of Hydrogenated Amorphous Silicon 1965.4 Deposition of Hydrogenated Amorphous Silicon 1975.4.1 Radio Frequency Plasma Enhanced Chemical Vapor Deposition 1985.4.2 Direct Plasma Enhanced Chemical Vapor Deposition Techniques 2005.4.3 Remote Plasma Enhanced Chemical Vapor Deposition Techniques 2025.4.4 Hotwire Chemical Vapor Deposition 2035.5 Amorphous Silicon Solar Cells 2045.5.1 Hydrogenated Amorphous Silicon Solar Cell Structure 2045.5.2 Hydrogenated Amorphous Silicon Solar Cell Configurations 2075.5.3 Design Approaches for Highly Efficient Solar Cells 2085.5.4 Light Trapping and Transparent Conductive Oxides 2095.5.5 Degradation of Hydrogenated Amorphous Silicon Solar Cells 2115.5.6 Multijunction Hydrogenated Amorphous Silicon Solar Cells 2125.6 Performance and Fabrication of Hydrogenated Amorphous Silicon Based Modules 2195.6.1 Energy Yield 2215.6.2 Fabrication of Hydrogenated Amorphous Silicon Based Modules 2235.6.3 Plasma enhanced Chemical Vapor Deposition Systems 2235.7 Applications 2275.8 Outlook 229Acknowledgments 230References 2306 Chalcopyrite Based Solar Cells 237Reiner Klenk, Martha Ch. Lux-Steiner6.1 Introduction 2376.2 Potential of Chalcopyrite Photovoltaic Modules 2376.3 Technology for the Preparation of Chalcopyrite Solar Cells and Modules 2396.3.1 Absorber 2406.3.2 Contacts 2446.4 Characterization and Modeling 2476.4.1 Cell Concept 2486.4.2 Carrier Density and Transport 2506.4.3 Loss Mechanisms 2516.5 Scaling Up and Production 2546.5.1 Cost Estimations 2576.5.2 Module Performance 2586.5.3 Sustainability 2596.6 Developing Future Chalcopyrite Technology 2606.6.1 Lightweight and Flexible Substrates 2606.6.2 Cadmium Free Cells 2616.6.3 Indium Free Absorbers 2636.6.4 Novel Back Contacts 2636.6.5 Bifacial Cells and Superstrate Cells 2636.6.6 Nonvacuum Processing 2646.6.7 Wide Gap and Tandem Cells 265References 2667 Cadmium Telluride Thin Film Solar Cells: Characterization, Fabrication and Modeling 277Marc Burgelman7.1 Introduction 2777.2 Materials and Cell Concepts for Cadmium Telluride Based Solar Cells 2787.2.1 Optical Properties of Cadmium Telluride 2797.2.2 Electrical Properties of Cadmium Telluride 2817.2.3 The Buffer Material: Cadmium Sulfide 2837.2.4 Window Materials for Cadmium Telluride Based Solar Cells 2857.3 Research Areas and Trends in Cadmium Telluride Solar Cells 2867.3.1 The Activation Treatment of Cadmium Telluride 2867.3.2 The Back Contact Structure 2887.3.3 Environmental Issues 2907.3.4 Other Research Areas and Trends 2917.4 Fabrication of Cadmium Telluride Cells and Modules 2947.4.1 Deposition Methods for Cadmium Telluride Based Solar Cells 2947.4.2 Design of Series Integrated Cadmium Telluride Modules 2967.4.3 Production of Cadmium Telluride Solar Modules 2977.5 Advanced Characterization and Modeling of Cadmium Telluride Solar Cells 2987.5.1 Characterization and Modeling: Introduction 2987.5.2 Characterization Methods for Cadmium Telluride Materials and Cells 2987.5.3 Modeling of Thin Film Cadmium Telluride Solar Cells 3037.6 Conclusions 314Acknowledgments 314References 3148 Charge Carrier Photogeneration in Doped and Blended Organic Semiconductors 325Vladimir I. Arkhipov, Heinz Bässler8.1 Introduction 3258.2 Exciton Dissociation in Neat and Homogeneously Doped Random Organic Semiconductors 3268.2.1 Intrinsic Photogeneration in Conjugated Polymers 3268.2.2 Sensitized Photogeneration of Charge Carriers in Homogenously Doped Conjugated Polymers 3288.2.3 Photogeneration of Charge Carriers at a Donor–Acceptor Interface 3358.3 Models of Exciton Dissociation in Homogeneously Doped Conjugated Polymers and in Polymer Based Donor/Acceptor Blends 3498.3.1 The Onsager–Braun Model 3498.3.2 Exciton Dissociation in Conjugated Polymers Homogeneously Doped with Electron Scavengers 3518.3.3 Exciton Dissociation at a Polymer Donor/Acceptor Interface 3538.4 Conclusions 357References 3589 Nanocrystalline Injection Solar Cells 363Michael Grätzel9.1 Introduction 3639.2 Band Diagram and Operational Principle of the Dye Sensitized Solar Cell 3649.3 The Importance of the Nanostructure 3659.3.1 Light Harvesting by a Sensitizer Monolayer Adsorbed on a Mesoscopic Semiconductor Film 3669.3.2 Enhanced Red and Near Infrared Response by Light Containment 3689.3.3 Light Induced Charge Separation and Conversion of Photons to Electric Current 3699.3.4 Charge Carrier Collection 3719.3.5 Quantum Dot Sensitizers 3749.4 Photovoltaic Performance of the Dye Sensitized Solar Cell 3759.4.1 Photocurrent Action Spectra 3759.4.2 Overall Conversion Efficiency Under Global AM1.5 Standard Reporting Conditions 3769.4.3 Increasing the Open Circuit Photovoltage 3779.5 Development of New Sensitizers and Redox Systems 3789.6 Solid State Dye Sensitized Solar Cells 3799.7 Dye Sensitized Solar Cell Stability 3799.7.1 Criteria for Long Term Stability of the Dye 3799.7.2 Kinetic Measurements 3809.7.3 Recent Experimental Results on Dye Sensitized Solar Cell Stability 3819.7.4 First Large Scale Field Tests and Commercial Developments 3829.8 Future Prospects 384Acknowledgments 384References 38410 Charge Transport and Recombination in Donor–Acceptor Bulk Heterojunction Solar Cells 387A. J. Mozer, N. S. Sariciftci10.1 Introduction 38710.2 Development of Bulk Heterojunction Solar Cells 38810.3 Bulk Heterojunction Solar Cells 39110.3.1 Operational Principles 39110.3.2 Nanomorphology–Property Relations 39410.3.3 Improving the Photon Harvesting 39710.4 Charge Carrier Mobility and Recombination 39910.4.1 Measurement Techniques 39910.4.2 Charge Transport in Conjugated Polymers 40110.4.3 Charge Transport and Recombination in Bulk Heterojunction Solar Cells 41210.5 Summary 421Acknowledgments 421References 42211 The Terawatt Challenge for Thin Film Photovoltaics 427Ken Zweibel11.1 Prologue 42711.2 ‘The Only Big Number Out There – 125 000 TW’ (Quote, Nate Lewis, 2004) 42811.3 Low Cost and the Idea of Thin Films 43111.4 A Bottom Up Analysis of Thin Film Module Costs 43111.4.1 Approach 43211.4.2 Results 43511.5 Other Aspects of the ‘Terawatt Challenge’ 45511.6 Risks and Perspective 458Acknowledgments 459Appendix 11.1 459Appendix 11.2 460References 460Index 463