Advanced Concepts in Photovoltaics

[BOOK DESCRIPTION]

Photovoltaic systems enable the sun's energy to be converted directly into electricity using semiconductor solar cells. The ultimate goal of photovoltaic research and development is to reduce the cost of solar power to reach or even become lower than the cost of electricity generated from fossil and nuclear fuels. The power conversion efficiency and the cost per unit area of the phototvoltaic system are critical factors that determine the cost of photovoltaic electricity. Until recently, the power conversion efficiency of single-junction photovoltaic cells has been limited to approximately 33% - the socalled Shockley-Queisser limit. This book presents the latest developments in photovoltaics which seek to either reach or surpass the Shockley-Queisser limit, and to lower the cell cost per unit area.Progress toward this ultimate goal is presented for the three generations of photovoltaic cells: the 1st generation based on crystalline silicon semiconductors; the 2nd generation based on thin film silicon, compound semiconductors, amorphous silicon, and various mesoscopic structures; and the 3rd generation based on the unique properties of nanoscale materials, new inorganic and organic photoconversion materials, highly efficient multi-junction cells with low cost solar concentration, and novel photovoltaic processes. The extent to which photovoltaic materials and processes can meet the expectations of efficient and cost effective solar energy conversion to electricity is discussed. Written by an international team of expert contributors, and with researchers in academia, national research laboratories, and industry in mind, this book is a comprehensive guide to recent progress in photovoltaics and essential for any library or laboratory in the field.

[TABLE OF CONTENTS]

Chapter 1 Crystalline Silicon Solar Cells with     1  (29)
High Efficiency
          Stefan W. Glunz
    1.1 Introduction                               1  (1)
    1.2 Efficiency Limitations                     2  (5)
      1.2.1 Theoretical Limitations: The Auger     2  (3)
      Limit
      1.2.2 Practical Limitations                  5  (2)
    1.3 Screen-printed Al-BSF Solar Cells on       7  (4)
    p-type Silicon
      1.3.1 Standard A1-BSF Cell                   9  (1)
      1.3.2 Improved Al-BSF Formation by Boron     10 (1)
      Co-doping
      1.3.3 Improved Emitter                       10 (1)
    1.4 Solar Cells with Dielectric Rear           11 (3)
    Passivation on p-type Silicon
      1.4.1 Rear Passivation Layers                12 (1)
      1.4.2 Contacting Schemes                     13 (1)
      1.4.3 Lifetime Limitations in Boron-doped    13 (1)
      p-type Silicon
    1.5 Solar Cells on n-type Silicon              14 (6)
      1.5.1 n-type BSF Cell Structures             15 (2)
      1.5.2 n-type Cell Structures with            17 (1)
      Dielectric Rear Passivation
      1.5.3 Heterojunction Solar Cells             17 (2)
      1.5.4 Back-contacted Back-junction Solar     19 (1)
      Cells
      1.5.5 Back-contacted Back-junction Solar     20 (1)
      Cells with Passivated Contacts
    1.6 Conclusion                                 20 (1)
    Acknowledgements                               21 (1)
    References                                     21 (9)
Chapter 2 Tandem and Multiple junction Devices     30 (31)
Based on Thin-film Silicon Technology
          Christophe Ballif
          Mathieu Boccard
          Karin Soderstrom
          Gregory Bugnon
          Fanny Meillaud
          Nicolas Wyrsch
    2.1 Introduction                               30 (2)
    2.2 Material Properties                        32 (6)
      2.2.1 Hydrogenated Amorphous Silicon         32 (2)
      (a-Si:H) and its Alloys
      2.2.2 Hydrogenated Microcrystalline          34 (4)
      Silicon (ｵc-Si:H) and its Alloys
    2.3 Basis of Thin-film Silicon-based           38 (3)
    Multiple-junction Devices
      2.3.1 Solar Cells Based on Thin Films of     38 (1)
      Silicon
      2.3.2 Possible Multiple-junction Devices     38 (2)
      Based on Thin Films of Silicon
      2.3.3 Matching Considerations                40 (1)
      2.3.4 Combining Light Management and         40 (1)
      High-quality Absorber Layers
    2.4 State of the Art                           41 (1)
    2.5 Current Limitations and Prospective        42 (9)
    Concepts
      2.5.1 Increasing Light Absorption in the     43 (5)
      Absorber
      2.5.2 Improvements in Silicon Materials      48 (3)
    2.6 Conclusions and Perspectives               51 (1)
    References                                     51 (10)
Chapter 3 Thin-film CdTe Photovoltaic Solar        61 (26)
Cell Devices
          Timothy Gessert
          Brian McCandless
          Chris Ferekides
    3.1 Introduction                               61 (9)
      3.1.1 History of CdTe Photovoltaic Devices   62 (3)
      3.1.2 Layer-specific Process Description     65 (5)
      for Superstrate CdTe Devices
    3.2 Important and Under-reported Processes     70 (11)
      3.2.1 Buffer Layers                          70 (2)
      3.2.2 Incorporation of Cu                    72 (2)
      3.2.3 Defects and Defect Modeling            74 (5)
      3.2.4 Junction Formation and Location        79 (2)
    3.3 Conclusions                                81 (1)
    Acknowledgements                               81 (1)
    References                                     81 (6)
Chapter 4 III-V Multi Junction Solar Cells         87 (31)
          Simon P. Philipps
          Andreas W. Bett
    4.1 Introduction                               87 (4)
    4.2 On the Efficiency of III-V                 91 (4)
    Multi-junction Solar Cells
      4.2.1 Photovoltaic Cells and                 91 (2)
      Monochromatic Light: A Perfect Match
      4.2.2 Towards a Match with the Solar         93 (2)
      Spectrum: Stacking Photovoltaic Cells
    4.3 The Technological Toolbox to Fabricate     95 (9)
    III-V Multi-junction Solar Cells
      4.3.1 Epitaxial Growth Methods               96 (2)
      4.3.2 Substrates                             98 (1)
      4.3.3 Epitaxial Growth Concepts              99 (2)
      4.3.4 Materials                              101(2)
      4.3.5 Post-growth Technological Processing   103(1)
    4.4 Some Members of the III-V                  104(4)
    Multi-junction Solar Cell Family
      4.4.1 Upright Metamorphic Devices on Ge      104(1)
      Substrates
      4.4.2 Inverted Metamorphic Multi-junction    105(1)
      Solar Cells
      4.4.3 III-V on Si                            106(2)
      4.4.4 Wafer-bonded Multi-junction Solar      108(1)
      Cells
      4.4.5 Lattice-matched Growth of more than    108(1)
      Three Junctions
    4.5 Conclusion                                 108(1)
    Acknowledgements                               109(1)
    References                                     109(9)
Chapter 5 Thin-film Photovoltaics Based on         118(68)
Earth-abundant Materials
          Diego Colombara
          Phillip Dale
          Laurence Peter
          Jonathan Scragg
          Susanne Siebentritt
    5.1 Introduction                               118(4)
      5.1.1 Future Requirements for                118(1)
      Photovoltaics: 2050 Scenarios
      5.1.2 Resource Implications for Thin-film    119(1)
      Photovoltaics
      5.1.3 Earth-abundant Absorbers               120(2)
      5.1.4 The Scope of the Chapter               122(1)
    5.2 Kesterite: a Case Study                    122(14)
      5.2.1 Iso-electronic Substitution: An        122(6)
      Introduction to Cu2ZnSnS(Se)4
      5.2.2 A Comparison of Phase Equilibria in    128(3)
      the Cu-In-Se and Cu-Zn-Sn-Se Systems
      5.2.3 Electronic Properties                  131(5)
    5.3 Preparative Routes to Earth-abundant       136(14)
    Absorber Films
      5.3.1 Thermodynamic Considerations           137(5)
      5.3.2 Kinetic Considerations                 142(2)
      5.3.3 Preparative Methods                    144(5)
      5.3.4 Summary                                149(1)
    5.4 Device Fabrication and Characterization    150(1)
    5.5 Other Earth-abundant Materials             151(18)
      5.5.1 Phase Equilibria Considerations        152(1)
      5.5.2 Phase Stability Considerations         153(4)
      5.5.3 Opto-electronic Considerations         157(2)
      5.5.4 Application of Criteria of Earth       159(10)
      Abundance, Thermodynamics, and
      Opto-electronic Properties to Other
      Potential Absorber Materials
    5.6 Summary and Outlook                        169(1)
    Acknowledgements                               169(1)
    References                                     170(16)
Chapter 6 Chemistry of Sensitizers for             186(56)
Dye-sensitized Solar Cells
          Peng Gao
          Michael Grutzel
          M.D.K. Nazeeruddin
    6.1 Introduction                               186(6)
    6.2 Ruthenium Sensitizers                      192(12)
      6.2.1 High Molar Extinction Coefficient      195(1)
      Sensitizers
      6.2.2 Panchromatic Ruthenium Sensitizers     195(5)
      6.2.3 Cyclometallated NCS-free Ruthenium     200(1)
      Sensitizers
      6.2.4 Cyclometallated NCS-free Ruthenium     201(3)
      Dyes with a Com/Con Redox Shuttle
    6.3 Metal-free Organic Sensitizers             204(13)
      6.3.1 Organic Sensitizers and their          206(2)
      Cobalt Electrolyte Compatibility
      6.3.2 Size Effect of the Donor Groups in     208(1)
      the Cobalt Electrolyte Compatibility of
      Dyes
      6.3.3 Towards Cobalt Electrolyte             209(4)
      Compatible Panchromatic Organic Dyes
      6.3.4 Donor-Chromophore-Acceptor-based       213(3)
      Asymmetric Diketopyrrolopyrrole
      Sensitizers
      6.3.5 Ullazine-based Sensitizers             216(1)
    6.4 Porphyrin Sensitizers                      217(6)
      6.4.1 Towards High Efficiency and Cobalt     219(2)
      Compatible meso-Porphyrin Sensitizers
      6.4.2 Towards Panchromatic, High             221(2)
      Efficiency and Cobalt Compatible
      meso-Porphyrin Sensitizers
    6.5 Perovskite Sensitizers for Solid-state     223(6)
    Solar Cells
      6.5.1 One-step Precursor Solution            225(1)
      Deposition
      6.5.2 Two-step Sequential Deposition         225(2)
      Method
      6.5.3 Dual-source Vapour Deposition          227(2)
    6.6 Conclusion                                 229(1)
    Acknowledgements                               230(1)
    References                                     231(11)
Chapter 7 Perovskite Solar Cells                   242(16)
          Nam-Gyu Park
    7.1 Introduction                               242(2)
    7.2 Synthesis of Organolead Halide             244(1)
    Perovskite
    7.3 Crystal Structure and Related Properties   244(2)
    7.4 Opto-electronic Properties                 246(3)
    7.5 Perovskite Solar Cell Fabrication          249(1)
    7.6 Device Structures and Performances         250(5)
      7.6.1 CH3NH3Pbi3-based Perovskite Solar      250(2)
      Cells
      7.6.2 Mixed Halide and Non-iodide            252(2)
      Perovskite Solar Cells
      7.6.3 Planar Heterojunction Without          254(1)
      Mesoporous Oxide Layers
    7.7 Summary                                    255(1)
    Acknowledgements                               255(1)
    References                                     255(3)
Chapter 8 All-oxide Photovoltaics                  258(29)
          Sven Ridde
          Arie Zaban
    8.1 Introduction to All-oxide Photovoltaics    258(1)
    8.2 Solar Cell Design Rules                    259(5)
      8.2.1 Light Absorption                       259(2)
      8.2.2 Charge Transport                       261(1)
      8.2.3 Selective Contacts                     262(1)
      8.2.4 Optimized Energy Levels at             263(1)
      Interfaces
    8.3 Metal Oxides for All-oxide Photovoltaics   264(5)
      8.3.1 Electronic Properties                  264(2)
      8.3.2 Metal Oxide Light Absorber             266(1)
      8.3.3 Wide Bandgap Metal Oxides              267(2)
    8.4 Cu2O-based Photovoltaics                   269(8)
      8.4.1 Cu2O Synthesis                         269(2)
      8.4.2 Electronic and Optical Properties      271(1)
      of Cu2O
      8.4.3 Cu2O Schottky Junction Cells           272(2)
      8.4.4 Cu2O-based Heterojunction Cells        274(2)
      8.4.5 Cu2O Homojunction Cells                276(1)
      8.4.6 Nano-structured Cu2O-based             276(1)
      Photovoltaic Cells
    8.5 Further Metal Oxide-based Photovoltaics    277(2)
      8.5.1 ZnO-Fe2O3 Heterojunction Solar Cells   277(1)
      8.5.2 Bi2O3 Solar Cells                      277(1)
      8.5.3 Ferro-electric BiFeO3 Solar Cells      278(1)
    8.6 Combinatorial Material Science for         279(2)
    Novel Metal Oxides
      8.6.1 Density Functional Theory              279(1)
      8.6.2 Combinatorial Material and Device      280(1)
      Fabrication
    References                                     281(6)
Chapter 9 Active Layer Limitations and             287(37)
Non-geminate Recombination in Polymer-Fullerene
Bulk Heterojunction Solar Cells
          Tracey M. Clarke
          Guanran Zhang
          Attila J. Mozer
    9.1 Introduction                               287(12)
    9.2 Active Layer Limitations                   299(2)
    9.3 Charge Transport and Recombination         301(8)
    9.4 Non-Langevin Bimolecular Recombination     309(5)
    9.5 Mechanism of Reduced Recombination         314(4)
    9.6 Summary and Outlook                        318(1)
    References                                     319(5)
Chapter 10 Singlet Fission and                     324(21)
1,3-Diphenylisobenzofuran as a Model Chromophore
          Justin C. Johnson
          Josef Michl
    10.1 Introduction                              324(6)
      10.1.1 Singlet Fission                       324(3)
      10.1.2 Singlet Fission Chromophores          327(1)
      10.1.3 Chromophore Coupling                  328(2)
    10.2 1,3-Diphenylisobenzofuran (1)             330(11)
      10.2.1 The Chromophore 1                     330(1)
      10.2.2 Polycrystalline Layers of 1           331(4)
      10.2.3 Covalent Dimers of 1                  335(6)
    10.3 Current and Future Activities             341(1)
    Acknowledgements                               342(1)
    References                                     342(3)
Chapter 11 Quantum Confined Semiconductors for     345(34)
Enhancing Solar Photoconversion through
Multiple Exciton Generation
          Matthew C. Beard
          Alexander H. Ip
          Joseph M. Luther
          Edward H. Sargent
          Arthur J. Nozik
    11.1 Introduction to Colloidal Quantum Dots    345(7)
      11.1.1 Tuning of Electronic Properties       345(2)
      11.1.2 Competition Between MEG and           347(3)
      Hot-carrier Cooling via Phonon Emission
      11.1.3 Benefits to Solar Photoconversion     350(2)
    11.2 Nanocrystal Synthesis and Physical        352(9)
    Properties
      11.2.1 Solution Phase Synthesis              352(2)
      11.2.2 Shape and Composition Control         354(4)
      11.2.3 Measuring Multiple Exciton            358(3)
      Generation
    11.3 Quantum Dot Solar Cells                   361(9)
      11.3.1 Quantum Dot Films                     361(3)
      11.3.2 Quantum Dot Material Selection        364(1)
      11.3.3 p-n Heterojunction Quantum Dot        365(3)
      Solar Cells
      11.3.4 Quantum Junction Solar Cells          368(1)
      11.3.5 Multiple Exciton Generation in a      368(1)
      Quantum Dot Solar Cell
      11.3.6 Multi-junction Solar Cells            369(1)
    11.4 Conclusions and Future Directions         370(2)
    Acknowledgements                               372(1)
    References                                     372(7)
Chapter 12 Hot Carrier Solar Cells                 379(46)
          Gavin Conibeer
          Jean-Fran輟is Guillemoles
          Feng Yu
          Hugo Levard
    12.1 Introduction to Hot Carrier cells         379(1)
    12.2 Modelling of Hot Carrier Solar Cells      380(14)
      12.2.1 Thermodynamic Analysis for the Hot    380(1)
      Carrier Cell
      12.2.2 Models for Ideal Hot Carrier Cells    381(2)
      12.2.3 Detailed Balance Models and Limit     383(3)
      of Efficiency
      12.2.4 The Mechanisms of Carrier             386(1)
      Thermalization
      12.2.5 Modelling of Hot Carrier Solar        387(1)
      Cell Efficiency
      12.2.6 Modelling of Non-ideal ESCs           388(3)
      12.2.7 Monte Carlo Modelling of Real         391(3)
      Material Systems
      12.2.8 Summary of Modelling Section          394(1)
    12.3 Hot Carrier Absorbers: Slowing of         394(6)
    Carrier Cooling
      12.3.1 Electron-Phonon Interactions          395(1)
      12.3.2 Phonon Decay Mechanisms               396(1)
      12.3.3 Nanostructures for the Absorber       397(2)
      12.3.4 Hot Carrier Cell Absorber             399(1)
      Requisite Properties
    12.4 Hot Carrier Absorber: Choice of           400(14)
    Materials
      12.4.1 Analogues of InN                      400(3)
      12.4.2 Modelling Phonon Properties in        403(6)
      Group IV and III-V compounds
      12.4.3 Phonon Modulation in Quantum Dot      409(5)
      Nanostructure Arrays for Absorbers
    12.5 Contacting Hot Carrier Cells              414(5)
      12.5.1 Modelling Optimized Materials for     414(3)
      Energy Selective Contacts
      12.5.2 Triple Barrier Resonant Tunnelling    417(1)
      Structures for Carrier Selection and
      Rectification
      12.5.3 Optical Coupling for Hot Carrier      418(1)
      Cells
    12.6 Summary and Conclusion                    419(2)
    References                                     421(4)
Chapter 13 Intermediate Band Solar Cells           425(30)
          Yoshitaka Okada
          Tomah Sogabe
          Yasushi Shoji
    13.1 Introduction                              425(3)
    13.2 Numerical Analysis of QD-IB Solar Cell    428(3)
    Characteristics
    13.3 Fabrication of QD-IB Solar Cells          431(18)
      13.3.1 Growth and Properties of              431(6)
      High-density InAs QD Arrays on High-index
      Substrate
      13.3.2 InAs/GaAs QD-IB Solar Cells           437(4)
      Fabricated on High-index Substrate
      13.3.3 Growth and Properties of              441(3)
      InAs/GaAsSb QDs with Type-II Band
      Alignment
      13.3.4 InAs/GaAsSb QD-IB Solar Cells with    444(4)
      Type-II Band Alignment
      13.3.5 Characteristics of QD-IB Solar        448(1)
      Cells under Concentrated Sunlight
    13.4 Conclusion and Future Research            449(2)
    Acknowledgements                               451(1)
    References                                     452(3)
Chapter 14 Spectral Conversion for Thin Film       455(34)
Solar Cells and Luminescent Solar Concentrators
          Wilfried van Sark
          Jessica de Wild
          Zachar Krumer
          Celso de Mello Donegci
          Ruud Schropp
    14.1 Introduction                              456(3)
      14.1.1 Spectral Conversion                   456(2)
      14.1.2 This Chapter                          458(1)
    14.2 Up-conversion for Thin Film Silicon       459(10)
      14.2.1 Introduction                          459(2)
      14.2.2 Up-conversion Results                 461(8)
    14.3 Luminescent Solar Concentrators           469(14)
      14.3.1 Operating Principles                  470(1)
      14.3.2 Efficiency                            471(2)
      14.3.3 Alternative Luminescent Species       473(3)
      14.3.4 Re-absorption                         476(7)
    14.4 Conclusion and Outlook                    483(1)
    Acknowledgements                               484(1)
    References                                     484(5)
Chapter 15 Triplet-triplet Annihilation            489(17)
Up-conversion
          Timothy W. Schmidt
          Murad J.Y. Tayebjee
    15.1 Introduction                              489(1)
    15.2 The Limiting Efficiency of a Single       490(2)
    Threshold Solar Cell
      15.2.1 Photon Ratchet Model                  490(2)
    15.3 Up-conversion                             492(3)
      15.3.1 Summary                               495(1)
    15.4 Triplet-triplet Annihilation              495(4)
      15.4.1 Typical TTA Up-conversion             496(1)
      Combinations
      15.4.2 Efficiency Considerations             497(2)
    15.5 Application to Photovoltaics              499(1)
    15.6 Measurement                               500(2)
    15.7 The Figure of Merit                       502(1)
    15.8 Prospects                                 503(1)
    References                                     504(2)
Chapter 16 Quantum Rectennas for Photovoltaics     506(41)
          Feng Yu
          Garret Moddel
          Richard Corkish
    16.1 Introduction                              506(1)
    16.2 History of Quantum Antennas for           507(5)
    Photovoltaics Research
      16.2.1 Optical and Infrared Rectennas        507(4)
      16.2.2 Wireless Power Transmission           511(1)
      16.2.3 Radio-powered Devices                 512(1)
      16.2.4 Radio Astronomy                       512(1)
    16.3 Research Problems Concerning Rectennas    512(14)
    for Photovoltaics
      16.3.1 Fundamental Problems                  512(8)
      16.3.2 Practical Problems                    520(6)
    16.4 Thermodynamics of Rectennas               526(5)
      16.4.1 Broadband Antenna Modeled as a        527(2)
      Resistor
      16.4.2 Energetics of Thermal Rectification   529(2)
    16.5 Quantum Rectification                     531(3)
    16.6 Broadband Rectification Efficiency        534(2)
    Limit
    16.7 High-frequency Rectifiers                 536(6)
      16.7.1 MIM/MIIM Rectifiers                   536(1)
      16.7.2 New Concepts for High Frequency       537(5)
    16.8 Summary and Conclusions                   542(1)
    Acknowledgements                               543(1)
    References                                     543(4)
Chapter 17 Real World Efficiency Limits: the       547(20)
Shockley-Queisser Model as a Starting Point
          Pabitra K. Nayak
          David Cahen
    17.1 Introduction                              547(2)
    17.2 Efficiency of Different                   549(14)
    Single-junction Cells and Performance
    Analysis Based on Empirical Criteria
      17.2.1 Possibilities for Technological       551(2)
      Progress
      17.2.2 Current Efficiency (JSC/JSC,max,      553(3)
      JMP/JSC,max and JMP/JSC)
      17.2.3 Photon Energy Loss: Present Status    556(7)
      of Single-junction Solar Cells
    17.3 Fill Factor and Disorder                  563(1)
    17.4 Conclusion and Outlook                    564(1)
    Acknowledgements                               564(1)
    References                                     564(3)
Chapter 18 Grid Parity and its Implications for    567(29)
Energy Policy and Regulation
          Muriel Watt
          Iain MacGill
    18.1 Introduction                              567(4)
      18.1.1 Photovoltaics' Early Promise and      567(1)
      Progress
      18.1.2 Photovoltaics Goes Mainstream         568(2)
      18.1.3 Where next for Photovoltaics          570(1)
    18.2 What is Photovoltaics Grid Parity?        571(5)
      18.2.1 Issues Around 'Grid Parity'           573(3)
    18.3 Past and Projected Photovoltaics and      576(5)
    Grid Cost Trajectories
      18.3.1 Photovoltaics Costs                   576(1)
      18.3.2 Grid Costs                            577(1)
      18.3.3 Implications for Residential          578(2)
      Photovoltaics Systems
      18.3.4 Implications for Utility-scale        580(1)
      Photovoltaics in Wholesale Energy Markets
    18.4 The Broader Context of Photovoltaics      581(2)
    Deployment
      18.4.1 Technology                            582(1)
      18.4.2 Market Access                         582(1)
      18.4.3 Social Acceptance                     583(1)
    18.5 A Changing Context for Photovoltaics      583(6)
    Policy Support
      18.5.1 The Rationale for Photovoltaics       583(1)
      Policy Support
      18.5.2 Photovoltaics Specific Policy         584(4)
      Approaches to Date
      18.5.3 Broader Policy Settings               588(1)
    18.6 Implications of Photovoltaics 'Grid       589(3)
    Parity' for Energy Markets
      18.6.1 Implications of High Photovoltaics    589(1)
      Penetration on Other Stakeholders
      18.6.2 Emerging Issues and Responses         590(2)
    18.7 Conclusion: Photovoltaics as Part of a    592(1)
    Broader Transformation
    References                                     593(3)
Subject Index                                      596