Electrochromism and Electrochromic Devices

Electrochromic materials, both organic and inorganic, have widespread applications in light-attenuation, displays and analysis. Written in an accessible manner, this book provides a comprehensive treatment of all types of electrochromic systems and their many applications. Coverage develops from electrochromic scope and history to new searching presentations of optical quantification and theoretical mechanistic models. Non-electrode electrochromism and photo-electrochromism are summarised, with updated comprehensive reviews of electrochromic oxides (tungsten-trioxide particularly), metal co-ordination complexes and metal-cyanometallates, viologens and other organics; and more recent exotics such as fullerenes, hydrides, and conjugated electroactive polymers are also covered. The book concludes by examining device construction and durability. With an extensive bibliography, recent advances in the field, modern applications and a step-by-step development from simple examples to sophisticated theories, this book is ideal for researchers in materials science, polymer science, electrical engineering, physics, chemistry, bioscience and (applied) optoelectronics. Half-title......Page 3 Title......Page 5 Copyright......Page 6 Contents......Page 7 Preface......Page 11 References......Page 13 Acknowledgements......Page 14 Symbols and units......Page 16 Abbreviations and acronyms......Page 19 1.1 Electrode reactions and colour: electrochromism......Page 25 1.2 Non-redox electrochromism......Page 27 1.3 Previous reviews of electrochromism and electrochromic work......Page 30 1.4.1 Electrochrome type......Page 31 1.4.2 Contrast ratio CR......Page 33 1.4.3 Response time τ......Page 34 1.4.4 Write–erase efficiency......Page 35 1.4.5 Cycle life......Page 36 1.4.6 Power consumption......Page 37 1.4.7 Coloration efficiency η......Page 39 1.4.8 Primary and secondary electrochromism......Page 40 1.5 Multiple-colour systems: electropolychromism......Page 41 References......Page 42 2.3 Prussian blue evocation in historic redox-coloration processes......Page 49 2.4 Twentieth century: developments up to 1980......Page 51 References......Page 54 3.1 Introduction......Page 57 3.2.1 A cell with dissolved ions as reactants: the Gibbs energy and electromotive force......Page 58 3.2.3 Electrode potentials defined and illustrated......Page 59 3.2.4 A cell with metal electrodes in contact with ions of those metals......Page 61 3.2.5 The cell emf and the electrode potentials: the hydrogen scale......Page 63 3.2.6 Electrochromic electrodes......Page 64 3.3 Rates of charge and mass transport through a cell: overpotentials......Page 65 3.3.1 Mass transport mechanisms......Page 67 3.3.3 Diffusion......Page 68 Faradaic and non-faradaic currents......Page 69 3.4.1 Butler–Volmer kinetics of electrode reactions......Page 70 3.4.2 Cyclic voltammetry......Page 72 3.4.4 Ellipsometry......Page 74 References......Page 75 4.1 Amount of colour formed: extrinsic colour......Page 76 4.2 The electrochromic memory effect......Page 77 4.3 Intrinsic colour: coloration efficiency η......Page 78 4.3.1 Intrinsic colour: composite coloration efficiency (CCE)......Page 81 4.4 Optical charge transfer (CT)......Page 84 4.5.1 A brief synopsis of colorimetric theory......Page 86 References......Page 95 5.1 Kinetic considerations for type-I and type-II electrochromes: transport of electrochrome through liquid solutions......Page 99 5.3 Kinetic considerations for bleaching type-II electrochromes and bleaching and coloration of type-III electrochromes: transport of counter ions through solid electrochromes......Page 103 5.3.1 Kinetic background: preliminary assumptions......Page 105 5.3.2 Kinetic complications......Page 110 Model of Faughnan and Crandall: potentiostatic coloration......Page 115 Model of Green: galvanostatic coloration......Page 120 The model of Ingram, Duffy and Monk: an electronic percolation threshold......Page 123 Model of Bohnke: reduction of WV via neutral inserted species......Page 125 Recent developments: intervalence between WVI and WIV......Page 126 Additional experimental results......Page 127 Model of Faughnan and Crandall: potentiostatic bleaching......Page 129 Model of Green: potentiostatic bleaching......Page 132 Additional experimental evidence for concentration gradients......Page 133 Discussion – coloration and bleaching......Page 134 References......Page 139 6.1 Introduction to metal-oxide electrochromes......Page 149 6.1.2 Stability and durability of oxide electrochromes......Page 152 6.1.3 The preparation of thin-film oxide electrochromes......Page 154 Chemical vapour deposition (CVD)......Page 155 Electrodeposition......Page 156 Sol-gel techniques......Page 158 Other methods: sputtering in vacuo......Page 160 6.1.4 Electrochemistry in electrochromic films of metal oxides......Page 162 Selected biblography......Page 163 Preparation of tungsten oxide electrochromes......Page 164 Redox properties of WO3 electrochromes......Page 166 Optical properties of tungsten oxide electrochromes......Page 168 Devices containing tungsten trioxide electrochrome......Page 173 Preparation of molybdenum oxide electrochromes......Page 175 Redox chemistry of molybdenum oxide electrochromes......Page 176 Optical properties of molybdenum oxide electrochromes......Page 177 Devices containing molybdenum oxide electrochromes......Page 178 Preparation of iridium oxide electrochromes......Page 179 The redox chemistry of iridium oxide electrochromes......Page 181 Optical properties of iridium oxide electrochromes......Page 182 6.2.4 Nickel oxide......Page 183 Preparation of nickel oxide electrochromes......Page 184 Redox electrochemistry......Page 185 Optical properties of nickel oxide electrochromes......Page 187 Electrochromic devices containing nickel oxide electrochromes......Page 188 6.3.1 Introduction......Page 189 Cerium oxide......Page 190 Cobalt oxide......Page 191 Copper oxide......Page 194 Iron oxide......Page 196 Manganese oxide......Page 199 Niobium oxide......Page 200 Praseodymium oxide......Page 203 Tantalum oxide......Page 205 Tin oxide......Page 207 Titanium oxide......Page 208 Vanadium oxide......Page 209 6.4.1 Introduction......Page 214 Tungsten oxide as electrochromic host......Page 215 Cerium oxide as electrochromic host......Page 217 Cobalt oxide as electrochromic host......Page 219 Indium oxide as an electrochromic host......Page 220 Iron oxide as electrochromic host......Page 222 Molybdenum oxide as electrochromic host......Page 223 Niobium oxide as electrochromic host......Page 224 Titanium oxide as electrochromic host......Page 225 Vanadium oxide as electrochromic host......Page 226 Ternary and higher oxides......Page 227 6.4.3 Electrochromic oxides incorporating precious metals......Page 228 6.4.4 Metal oxyfluorides......Page 229 References......Page 230 7.1 Redox coloration and the underlying electronic transitions......Page 277 7.2.1 Polypyridyl complexes in solution......Page 278 7.2.2 Reductive electropolymerisation of polypyridyl complexes......Page 279 7.2.3 Oxidative electropolymerisation of polypyridyl complexes......Page 280 7.2.4 Spatial electrochromism of polymeric polypyridyl complexes......Page 281 7.3.1 Introduction to metal phthalocyanines and porphyrins......Page 282 7.3.2 Sublimed bis(phthalocyaninato)lutetium(III) films......Page 283 7.3.3 Other metal phthalocyanines......Page 284 7.3.4 Electrochemical routes to metallophthalocyanine electrochromic films......Page 285 7.3.5 Langmuir–Blodgett metallophthalocyanine electrochromic films......Page 286 7.3.6 Species related to metallophthalocyanines......Page 287 7.3.7 Electrochromic properties of porphyrins......Page 288 7.4.1 Significance of the near-infrared region......Page 289 7.4.2 Planar dithiolene complexes of Ni, Pd and Pt......Page 290 7.4.3 Mixed-valence dinuclear complexes of ruthenium......Page 291 7.4.4 Tris(pyrazolyl)borato-molybdenum complexes......Page 293 7.4.5 Ruthenium and osmium dioxolene complexes......Page 294 References......Page 298 8.1 Prussian blue systems: history and bulk properties......Page 306 8.2 Preparation of Prussian blue thin films......Page 307 8.3 Electrochemistry, in situ spectroscopy and characterisation of Prussian blue thin films......Page 309 8.4 Prussian blue electrochromic devices......Page 313 8.5 Prussian blue analogues......Page 315 8.5.2 Vanadium hexacyanoferrate......Page 316 8.5.3 Nickel hexacyanoferrate......Page 317 8.5.5 Palladium hexacyanoferrate......Page 318 8.5.7 Miscellaneous Prussian blue analogues......Page 319 References......Page 320 9.1 Fullerene-based electrochromes......Page 327 9.2 Other carbon-based electrochromes......Page 328 Bismuth......Page 329 Lead......Page 330 9.4 Reflecting metal hydrides......Page 331 References......Page 333 10.1.2 Types of electroactive conducting polymers......Page 336 10.1.3 Mechanism of oxidative polymerisation of resonance-stabilised aromatic molecules......Page 337 10.1.4 Conductivity and optical properties......Page 338 10.2.1 Introduction to poly(thiophene)s......Page 342 10.2.2 Poly(thiophene)s derived from substituted thiophenes and oligothiophenes......Page 344 10.2.3 Poly(thiophene)s derived from 3,4-(ethylenedioxy)thiophenes......Page 345 10.3 Poly(pyrrole)s and dioxypyrroles as electrochromes......Page 351 10.4 Poly(aniline)s as electrochromes......Page 352 10.5.2 All-polymer ECDs......Page 355 10.6.1 Novel routes to castable poly(aniline) films......Page 356 10.7 ECDs using both electroactive conducting polymers and inorganic electrochromes......Page 357 10.8 Conclusions and outlook......Page 358 References......Page 359 11 Introduction......Page 365 11.2 Bipyridilium redox chemistry......Page 366 11.3.1 Electrodes derivatised with viologens for ECD inclusion......Page 370 11.3.3 Soluble-to-insoluble viologen electrochromes for ECD inclusion......Page 372 11.3.4 Applications of bipyridilium systems in electrochromic devices......Page 373 11.3.5 The effect of the bipm N substituents......Page 375 11.3.6 The effect of the counter anion......Page 376 11.3.7 The kinetics and mechanism of viologen electrocoloration......Page 378 11.3.8 Micellar species......Page 379 11.3.9 The write–erase efficiency......Page 380 11.3.10 Attempts to improve the write–erase efficiency......Page 383 11.4.1 Displays based on viologens adsorbed on nanostructured titania......Page 384 11.4.4 Viologens incorporated within paper......Page 389 References......Page 390 12.1.1 Aromatic amine electrochromes......Page 398 12.1.3 Cyanine electrochromes......Page 400 12.1.4 Methoxybiphenyl electrochromes......Page 403 12.1.5 Quinone electrochromes......Page 405 12.1.6 Thiazine electrochromes......Page 409 12.2.1 Pyrazoline electrochromes......Page 411 12.2.2 Tetracyanoquinodimethane (TCNQ) electrochromes......Page 412 12.2.3 Tetrathiafulvalene (TTF) electrochromes......Page 413 References......Page 415 13.2 Reflective electrochromic devices: electrochromic car mirrors......Page 419 13.3 Buildings......Page 421 13.3.2 Aircraft – the first ubiquitous ECD window application: Gentex and Boeing......Page 424 13.4 Electrochromic displays for displaying images and data......Page 425 13.5 ECD light modulators and shutters in message-laser applications......Page 428 13.6 Electrochromic paper......Page 429 13.7 Electrochromes applied in quasi-electrochromic or non-electrochromic processes: sensors and analysis......Page 430 13.8 Miscellaneous electrochromic applications......Page 431 13.9 Combinatorial monitoring of multiples of varied electrode materials......Page 433 References......Page 434 14.1 Fundamentals of ECD construction......Page 441 14.2 Electrolyte layers for ECDs......Page 443 Polyelectrolytes......Page 444 Polymer electrolytes......Page 445 14.3.1 Transparent conductors......Page 446 14.3.2 Opaque and metallic conductors......Page 447 14.4 Device encapsulation......Page 448 References......Page 449 15.2 Direction of beam......Page 457 15.3.2 Photoconductive layers......Page 458 15.3.3 Photovoltaic materials......Page 461 15.4 Photochromic-electrochromic systems......Page 462 References......Page 464 16.1 Introduction......Page 467 16.2 Durability of transparent electrodes......Page 468 16.4 Enhancing the durability of electrochrome layers......Page 469 16.5 Durability of electrochromic devices after assembly......Page 470 References......Page 473 Index......Page 476