Electrochromic Materials and Devices

Electrochromic materials can change their properties under the influence of an electrical voltage or current. Different classes of materials show this behavior such as transition metal oxides, conjugated polymers, metal-coordinated complexes and organic molecules. As the color change is persistent, the electric field needs only to be applied to initiate the switching, allowing for applications such as low-energy consumption displays, light-adapting mirrors in the automobile industry and smart windows for which the amount of transmitted light and heat can be controlled. The first part of this book describes the different classes and processing techniques of electrochromic materials. The second part highlights nanostructured electrochromic materials and device fabrication, and the third part focuses on the applications such as smart windows, adaptive camouflage, biomimicry, wearable displays and fashion. The last part rounds off the book by device case studies and environmental impact issues.

Table of Contents:
Preface XIX Acknowledgements XXI List of Contributors XXIII Part I ElectrochromicMaterials and Processing 1 1 ElectrochromicMetal Oxides: An Introduction to Materials and Devices 3 Claes-Göran Granqvist 1.1 Introduction 3 1.2 Some Notes on History and Early Applications 5 1.3 Overview of Electrochromic Oxides 6 1.3.1 RecentWork on Electrochromic Oxide Thin Films 7 1.3.2 Optical and Electronic Effects 9 1.3.3 Charge Transfer Absorption in Tungsten Oxide 11 1.3.4 Ionic Effects 14 1.3.5 On the Importance of Thin-Film Deposition Parameters 18 1.3.6 Electrochromism in Films of Mixed Oxide: TheW–Ni-Oxide System 21 1.4 Transparent Electrical Conductors and Electrolytes 23 1.4.1 Transparent Electrical Conductors: Oxide Films 25 1.4.2 Transparent Electrical Conductors: Metal-Based Films 26 1.4.3 Transparent Electrical Conductors: Nanowire-Based Coatings and Other Alternatives 27 1.4.4 Electrolytes: Some Examples 29 1.5 Towards Devices 30 1.5.1 Six Hurdles for Device Manufacturing 31 1.5.2 Practical Constructions of Electrochromic Devices 32 1.6 Conclusions 33 2 ElectrochromicMaterials Based on Prussian Blue and Other Metal Metallohexacyanates 41 David R. Rosseinsky and Roger J. Mortimer 2.1 The Electrochromism of Prussian Blue 41 2.1.1 Introduction 41 2.1.2 Electrodeposited PB Film and Comparisons with Bulk PB 42 2.1.3 PB Prepared from Direct Cell Reaction, with No Applied Potential 45 2.1.4 Layer-by-Layer Deposition of PB 46 2.1.5 PB on Graphene 46 2.1.6 Alternative Preparations of PB: PB from Colloid and Similar Origins 46 2.1.7 Alternative Electrolytes Including Polymeric for PB Electrochromism 47 2.2 Metal Metallohexacyanates akin to Prussian Blue 48 2.2.1 Ruthenium Purple RP 48 2.2.2 Vanadium Hexacyanoferrate 48 2.2.3 Nickel Hexacyanoferrate 48 2.3 Copper Hexacyanoferrate 49 2.3.1 Palladium Hexacyanoferrate 49 2.3.2 Indium Hexacyanoferrate and Gallium Hexacyanoferrate 49 2.3.3 Miscellaneous PB Analogues as Hexacyanoferrates 49 2.3.4 Mixed-Metal and Mixed-Ligand PB Analogues Listed 50 3 Electrochromic Materials and Devices Based on Viologens 57 Paul M. S. Monk, David R. Rosseinsky, and Roger J. Mortimer 3.1 Introduction, Naming and Previous Studies 57 3.2 Redox Chemistry of Bipyridilium Electrochromes 58 3.3 Physicochemical Considerations for Including Bipyridilium Species in ECDs 61 3.3.1 Type-1 Viologen Electrochromes 61 3.3.2 Type-2 Viologen Electrochromes 61 3.3.3 Type-3 Viologen Electrochromes 68 3.4 Exemplar Bipyridilium ECDs 72 3.4.1 The Philips Device 72 3.4.2 The ICI Device 72 3.4.3 The IBM Device 74 3.4.4 The Gentex Device 74 3.4.5 The NTERA Device 76 3.4.6 The NanoChromics Cell 76 3.4.7 The Grätzel Device 78 3.5 Elaborations 78 3.5.1 The Use of Pulsed Potentials 79 3.5.2 Electropolychromism 79 3.5.3 Viologen Electrochemiluminescence 79 3.5.4 Viologens Incorporated within Paper 80 4 Electrochromic Devices Based on Metal Hexacyanometallate/Viologen Pairings 91 Kuo-Chuan Ho, Chih-Wei Hu, and Thomas S. Varley 4.1 Introduction 91 4.1.1 Overview of Prussian Blue and Viologen Electrochromic Devices 92 4.2 Hybrid (Solid-with-Solution) Electrochromic Devices 93 4.2.1 Prussian Blue and Heptyl Viologen Solid-with-Solution-Type ECD 93 4.2.1.1 Preparation and Characterisation of PBThin Film and HV(BF4)2 94 4.2.1.2 Redox Behaviours and Visible Spectra of the PB Film and HV(BF4)2 Solution 94 4.2.1.3 Operating Parameters and Properties of PHECD 95 4.2.1.4 Analogous Devices 96 4.2.2 PBThin Film and Viologen in Ionic Liquid–Based ECD 97 4.3 All-Solid Electrochromic Devices 97 4.3.1 Prussian Blue and Poly(butyl viologen) Thin-Film ECD 97 4.3.1.1 Preparation of Poly(butyl viologen)Thin Film 97 4.3.1.2 Electrochemical and Optical Properties of Poly(butyl viologen) Thin Films 98 4.3.1.3 Electrochromic Performance of PBV-PB ECD 99 4.3.2 Prussian Blue and Viologen Anchored TiO2-Based ECD 99 4.3.3 Polypyrrole-Prussian Blue Composite Film and Benzylviologen Polymer–Based Thin-Film-Type ECD 100 4.3.3.1 Preparation of PP-PBThin-Film 101 4.3.3.2 Performance of the PP-PB Thin-Film and pBPQ-Based Electrochromic Device 101 4.3.4 PBThin-Film and Viologen-Doped Poly(3,4-ethylenedioxythiopene) Polymer–Based ECD 102 4.3.5 Other Solid-State Viologens 103 4.4 Other Metal Hexacyanometallate-Viologen-Based ECDs 104 4.5 Prospects for Metal Hexacyanometallate-Viologen-Based ECDs 105 5 Conjugated Electrochromic Polymers: Structure-Driven Colour and Processing Control 113 Aubrey L. Dyer, Anna M. Österholm, D. Eric Shen, Keith E. Johnson, and John R. Reynolds 5.1 Introduction and Background 113 5.1.1 Source of Electrochromism in Conjugated Polymers 113 5.1.1.3 Steric Interactions 120 5.1.1.4 Fused Aromatics 122 5.2 Representative Systems 123 5.2.1 Coloured-to-Transmissive Polymers 123 5.2.2 Anodically Colouring 139 5.2.3 Inducing Multicoloured States in ECPs 143 5.3 Processability of Electrochromic Polymers 152 5.3.1 Electrochemical Polymerisation 152 5.3.2 Functionalisation of ECPs for Achieving Organic Solubility 156 5.3.3 Aqueous Processability and Compatibility 158 5.3.4 Methods for Patterning 165 5.4 Summary and Perspective 168 6 Electrochromism within Transition-Metal Coordination Complexes and Polymers 185 Yu-Wu Zhong 6.1 Electronic Transitions and Redox Properties of Transition-Metal Complexes 185 6.2 Electrochromism in Reductively Electropolymerised Films of Polypyridyl Complexes 187 6.3 Electrochromism in Oxidatively Electropolymerised Films of Transition-Metal Complexes 192 6.4 Electrochromism in Self-Assembled or Self-Adsorbed Multilayer Films of Transition-Metal Complexes 196 6.5 Electrochromism in Spin-Coated or Drop-CastThin Films of Transition-Metal Complexes 200 6.6 Conclusion and Outlook 204 7 Organic Near-Infrared Electrochromic Materials 211 Bin Yao, Jie Zhang, and XinhuaWan 7.1 Introduction 211 7.2 Aromatic Quinones 212 7.3 Aromatic Imides 216 7.4 Anthraquinone Imides 218 7.5 Poly(triarylamine)s 221 7.6 Conjugated Polymers 228 7.7 Other NIR Electrochromic Materials 235 7.8 Conclusion 236 8 Metal Hydrides for Smart-Window Applications 241 Kazuki Yoshimura 8.1 Switchable-Mirror Thin Films 241 8.2 Optical Switching Property 242 8.3 Switching Durability 243 8.4 Colour in the Transparent State 244 8.5 Electrochromic Switchable Mirror 245 8.6 Smart-Window Application 246 Part II Nanostructured Electrochromic Materials and Device Fabrication 249 9 Nanostructures in Electrochromic Materials 251 Shanxin Xiong, Pooi See Lee, and Xuehong Lu 9.1 Introduction 251 9.1.1 Why Nanostructures? 251 9.1.2 Classification of Nanostructural Electrochromic Materials 252 9.1.3 Preparation Method 253 9.2 Nanostructures of Transition Metal Oxides (TMOs) 253 9.2.1 Introduction 253 9.2.2 Single TMO Systems 257 9.2.3 Binary TMO Systems 261 9.3 Nanostructures of Conjugated Polymers 262 9.3.1 Introduction 262 9.3.2 Polythiophene and Its Derivatives 263 9.3.3 Polyaniline 264 9.3.4 Polypyrrole 266 9.4 Nanostructures of Organic-Metal Complexes and Viologen 267 9.4.1 Introduction 267 9.4.2 Organic-Metal Complexes 267 9.4.3 Viologens 268 9.5 Electrochromic Nanocomposites and Nanohybrids 268 9.5.1 Introduction 268 9.5.2 Nanocomposites of Electrochromic Materials 269 9.5.3 Nanocomposites of Electrochromic/Non-Electrochromic Active Materials 274 9.6 Conclusions and Perspective 281 10 Advances in Polymer Electrolytes for Electrochromic Applications 289 Alice Lee-Sie Eh, Xuehong Lu, and Pooi See Lee 10.1 Introduction 289 10.2 Requirements of Polymer Electrolytes in Electrochromic Applications 290 10.3 Types of Polymer Electrolytes 291 10.3.1 Solid Polymer Electrolytes (SPEs) 292 10.3.2 Gel Polymer Electrolytes (GPEs) 292 10.3.3 Polyelectrolytes 293 10.3.4 Composite Polymer Electrolytes (CPEs) 294 10.4 Polymer Hosts of Interest in Electrochromic Devices 294 10.4.1 PEO/PEG-Based Polymer Electrolytes 295 10.4.2 PMMA-Based Polymer Electrolytes 296 10.4.3 PVDF-Based Polymer Electrolytes 297 10.4.4 Ionic Liquid–Based Polymer Electrolytes 300 10.4.5 Poly(propylene carbonate) (PPC)-Based Polymer Electrolytes 302 10.5 Recent Trends in Polymer Electrolytes 303 10.5.1 Flexible, Imprintable, Bendable and Shape-Conformable Polymer Electrolytes 303 10.5.2 Potentially 'Green' Biodegradable Polymer Electrolytes Using Naturally Available Polymer Host 303 10.6 Future Outlook 305 10.6.1 Recent Trends in Electrochromic Devices 305 10.6.2 Challenges in Creating Versatile Polymer Electrolytes for EC Devices 307 11 Gyroid-Structured Electrodes for Electrochromic and Supercapacitor Applications 311 Maik R.J. Scherer and Ullrich Steiner 11.1 Introduction to Nanostructured Electrochromic Electrodes 311 11.1.1 Three-Dimensional Nanostructuring Strategies 313 11.2 Polymer Self-Assembly and the Gyroid Nanomorphology 315 11.2.1 Copolymer Microphase Separation 315 11.2.2 Double-Gyroid 316 11.2.3 Synthesis of Mesoporous DG Templates 318 11.3 Gyroid-Structured Vanadium Pentoxide 320 11.3.1 Electrochemical Characterisation of V2O5 Electrodes 322 11.3.2 Electrochromic Displays Based on V2O5 Electrodes 322 11.3.3 Electrochromic V2O5 Supercapacitors 324 11.4 Gyroid-Structured Nickel Oxide 326 11.4.1 Electrochromic Displays Based on NiO Electrodes 328 11.5 Concluding Remarks 329 12 Layer-by-Layer Assembly of ElectrochromicMaterials: On the Efficient Method for Immobilisation of Nanomaterials 337 Susana I. Córdoba de Torresi, Jose R. Martins Neto, Marcio Vidotti, and Fritz Huguenin 12.1 Introduction to the Layer-by-Layer Deposition Technique 337 12.2 Layer-by-Layer Assembly in Electrochromic Materials 337 12.2.1 Layer-by-Layer Assembly of Conjugated Conducting Polymers 338 12.2.2 Layer-by-Layer Assembly of Intervalence Charge Transfer Coloration Materials 340 12.3 Layer-by-Layer Assembly of Metal Oxides 342 12.3.1 Tungsten Oxide 344 12.3.2 Hexaniobate 346 12.3.3 Vanadium Oxide 346 12.3.4 Titanium Oxide 348 12.3.5 Nickel Hydroxide 349 12.4 Layer-by-Layer and Electrophoretic Deposition for Nanoparticles Immobilisation 351 12.4.1 Comparing Layer-by-Layer and Electrophoretic Deposition 351 13 Plasmonic Electrochromism of Metal Oxide Nanocrystals 363 Anna Llordes, Evan L. Runnerstrom, Sebastien D. Lounis, and Delia J.Milliron 13.1 Introduction to Plasmonic Electrochromic Nanocrystals 363 13.2 History of Electrochromism in Metal and Semiconductor Nanocrystals 368 13.3 Doped Metal Oxide Colloidal Nanocrystals as Plasmonic Electrochromic Materials 377 13.3.1 Colloidal Synthesis of Doped Metal Oxide Nanocrystals 377 13.3.2 Plasmonic Electrochromic Electrodes Based on Colloidal ITO and AZO Nanocrystals 379 13.3.3 Design Principles for Nanocrystal-Based Plasmonic Electrochromics 382 13.4 Advanced Electrochromic Electrodes Constructed from Colloidal Plasmonic NCs 383 13.4.1 NIR-Selective Mesoporous Architectured Electrodes Based on Plasmonic Colloidal Nanocrystals 384 13.4.2 Dual-Band Nanocrystal-in-Glass Composite Electrodes Based on Plasmonic Colloidal Nanocrystals and Conventional Electrochromic Materials 385 13.4.3 Other Advanced Composite Electrochromic Electrodes Obtained from Non-Colloidal Approaches 391 13.5 Conclusions and Outlook 393 Part III Applications of Electrochromic Materials 399 14 Solution-Phase Electrochromic Devices and Systems 401 Harlan J. Byker 14.1 Introduction 401 14.2 Early History of Solution-Phase EC 402 14.3 The World’s Most Widely Used Electrochromic Material 405 14.4 Commercialisation of EC Devices 406 14.5 Reversibility and Stability in Solution-Phase EC Systems 409 14.6 Thickened and Gelled Solution-Phase Systems 411 14.7 Nernst Equilibrium, Disproportionation and Stability 413 14.8 Closing Remarks 415 15 Electrochromic SmartWindows for Dynamic Daylight and Solar Energy Control in Buildings 419 Bjørn Petter Jelle 15.1 Introduction 419 15.2 Solar Radiation 421 15.3 Solar Radiation throughWindow Panes and Glass Structures 421 15.4 Solar Radiation Modulation by Electrochromic Windows 425 15.5 Experimental 427 15.5.1 Glass Samples and Window Pane Configurations 427 15.5.2 UV-VIS-NIR Spectrophotometry 428 15.5.3 Emissivity Determination by Specular IR Reflectance 428 15.5.4 Emissivity Determination by Heat Flow Meter 428 15.5.5 Emissivity Determination by Hemispherical Reflectance 429 15.5.6 Actual Emissivity Determinations inThis Study 430 15.6 Measurement and Calculation Method of Solar Radiation Glazing Factors 430 15.6.1 Ultraviolet Solar Transmittance 430 15.6.2 Visible Solar Transmittance 431 15.6.3 Solar Transmittance 431 15.6.4 Solar Material Protection Factor (SMPF) 432 15.6.5 Solar Skin Protection Factor (SSPF) 433 15.6.6 External Visible Solar Reflectance 434 15.6.7 Internal Visible Solar Reflectance 434 15.6.8 Solar Reflectance 435 15.6.9 Solar Absorbance 436 15.6.10 Emissivity 436 15.6.11 Solar Factor (SF) 440 15.6.12 Colour Rendering Factor (CRF) 449 15.6.13 Additional Heat Transfer 451 15.6.14 Number of Glass Layers in a Window Pane 452 15.6.15 General Calculation Procedures 452 15.7 Spectroscopic Measurement and Calculation of Solar Radiation Glazing Factors 452 15.7.1 Spectroscopic Data for Float Glass and Low Emittance Glass 453 15.7.2 Spectroscopic Data for Dark Silver Coated Glass 455 15.7.3 Spectroscopic Data for Electrochromic Windows 456 15.7.4 Solar Radiation Glazing Factors for Float Glass, Low Emittance Glass, Dark Silver Coated Glass and Two-Layer and Three-Layer Window Pane Configurations 461 15.7.5 Solar Radiation Glazing Factors for Electrochromic Windows 465 15.7.6 Miscellaneous Other Electrochromic Properties 470 15.8 Commercial Electrochromic Windows and the Path Ahead 475 15.9 Increased Application of Solar Radiation Glazing Factors 476 15.10 Conclusions 476 15.A Appendix: Tables for Calculation of Solar Radiation Glazing Factors 477 15.B Appendix: Tables for Calculation ofThermal Conductance 488 16 Fabric Electrochromic Displays for Adaptive Camouflage, Biomimicry, Wearable Displays and Fashion 503 Michael T. Otley,Michael A. Invernale, and Gregory A. Sotzing 16.1 Introduction 503 16.1.1 Colour-Changing Technologies Background 504 16.1.2 Previous Work 505 16.1.3 Conductivity Trends of PEDOT-PSS Impregnated Fabric and the Effect of Conductivity on Electrochromic Textile 510 16.1.4 The Effects of Coloured-Based Fabric on Electrochromic Textile 513 16.1.5 Other Electrochromic Fabric 514 16.2 Non-Electrochromic Colour-Changing Fabric 517 16.2.1 Thermochromic Fabric 517 16.2.2 Photochromic Fabric 517 16.2.3 LED and LCD Technology 518 16.3 Conclusion 519 Part IV Device Case Studies, Environmental Impact Issues and Elaborations 525 17 Electrochromic Foil: A Case Study 527 Claes-Göran Granqvist 17.1 Introduction 527 17.2 Device Design and Optical Properties of Electrochromic Foil 528 17.3 Comments on Lifetime and Durability 532 17.4 Electrolyte Functionalisation by Nanoparticles 538 17.5 Comments and Conclusion 541 18 Life Cycle Analysis (LCA) of Electrochromic SmartWindows 545 Uwe Posset and Matthias Harsch 18.1 Life Cycle Analysis 545 18.2 Application of LCA to Electrochromic SmartWindows 549 18.3 LCA of Novel Plastic-Film-Based Electrochromic Devices 560 18.4 LCA for EC Target Applications 564 18.4.1 Automotive Sunroof Case 564 18.4.2 Appliance Example:Window Case for a House-Hold Oven 566 18.4.3 Aircraft CabinWindow Case 567 18.5 Conclusion 568 19 Electrochromic Glazing in Buildings: A Case Study 571 John Mardaljevic, Ruth KellyWaskett, and Birgit Painter 19.1 Introduction 571 19.1.1 Daylight in Buildings 572 19.1.2 The Importance of View 572 19.2 Variable Transmission Glazing for Use in Buildings 573 19.2.1 Chromogenic Glass 573 19.2.2 VTG Performance Characteristics 574 19.2.3 EC Product Details and Practicalities 577 19.2.4 Operational Factors 578 19.2.5 Zoning of EC Glazing 580 19.2.6 Performance Prediction Using Building Simulation Tools 582 19.2.7 Occupant-Based Studies 583 19.3 Case Study:The De Montfort EC Office Installation 584 19.3.1 Background 584 19.3.2 Installation of the EC Glazing 585 19.3.3 Subjective Data Collection 587 19.3.4 Measurement of Physical Quantities 587 19.3.5 The Daylight Illumination Spectrum with EC Glazing 588 19.4 Summary 591 20 Photoelectrochromic Materials and Devices 593 Kuo-Chuan Ho, Hsin-Wei Chen, and Chih-Yu Hsu 20.1 Introduction 593 20.2 Structure Design of the PECDs 594 20.2.1 Separated-Type PECD (Type I):The Dye-Sensitised TiO2 Layer is Separated from the Electrochromic Layer 594 20.2.1.1 Inorganic Materials as EC Layers 599 20.2.1.2 Conjugated Conducting Polymer Materials as EC Layers 604 20.2.2 Combined-Type PECD (Type II):The Dye-Sensitised TiO2 Layer is Combined with the Electrochromic Layer 610 20.2.3 Non-Symmetric-Type PECDs (Type III): The Active Area of the Dye-Sensitised TiO2 Layer is Non-Symmetric to the Electrochromic Layer 613 20.2.4 Parallel-Type PECDs: Where the Dye-Sensitised TiO2 Layer is Parallel and Separated with the Electrochromic Layer. The Electrolytes for Both Layers are Different forTheir Optimal Performance 616 20.2.5 Prospects 619 Appendix Definitions of Electrochromic Materials and Device Performance Parameters 623 Roger J. Mortimer, Paul M. S. Monk, and David R. Rosseinsky A.1 Contrast Ratio CR 623 A.2 Response Time τ 624 A.3 Write–Erase Efficiency 624 A.4 Cycle Life 624 A.5 Coloration Efficiency η 625 Index 627

About the Author :
Paul M. S. Monk received his PhD in the electrochemistry of novel electrochromic viologen species at Exeter University in 1989. A postdoctoral research fellow position (1989-91) at the University of Aberdeen, in Scotland, was followed by lecturing positions in Physical Chemistry at Manchester Polytechnic (1991-2) then Manchester Metropolitan University (1992-2007). He is currently employed as a Vicar in an inner-city parish in Oldham, Greater Manchester, UK. Roger J. Mortimer was Professor in Physical Chemistry at Loughborough University between 2006 and his untimely death in 2015. He graduated from Imperial College London with a PhD in heterogeneous catalysis at sold-liquid interfaces. After a postdoctoral research fellowship (1980-81) and visiting associate in chemistry (1988) at the California Institute of Technology, he became demonstrator and a Research Assistant at Exeter University. Lecturing positions in Physical Chemistry ensued at Anglia Ruskin University (1984-87) and Analytical Chemistry at Sheffield Hallam University (1987-89), followed by his appointment as a Lecturer in Physical Chemistry at Loughborough University in 1989. David R. Rosseinsky is an Emeritus Professor and Honorary Research Fellow in Physics at Exeter University, having been Reader in Physical Chemistry there from 1979-1998. After Rhodes University he pursued studies leading to PhD then DSc on charge transfer interactions at Manchester University. Following a sojourn at the University of Pennsylvania, from 1959 he became a lecturer at the University of the Witwatersrand in Johannesburg and in 1961, lecturer at Exeter University. With his ex research-student H Kellawi (by then Prof at Damascus University, on sabbatical), they studied Prussian blue and other electrochromic systems, extended in an invited appointment to SIMTech, Singapore, 2000-2002.