Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of symbols and units
- List of abbreviations and acronyms
- 1 Introduction to electrochromism
- 2 A brief history of electrochromism
- 3 Electrochemical background
- 4 Optical effects and quantification of colour
- 5 Kinetics of electrochromic operation
- 6 Metal oxides
- 7 Electrochromism within metal coordination complexes
- 8 Electrochromism by intervalence charge-transfer coloration: metal hexacyanometallates
- 9 Miscellaneous inorganic electrochromes
- 10 Conjugated conducting polymers
- 11 The viologens
- 12 Miscellaneous organic electrochromes
- 13 Applications of electrochromic devices
- 14 Fundamentals of device construction
- 15 Photoelectrochromism
- 16 Device durability
- Index
- Plate Section
- References
15 - Photoelectrochromism
Published online by Cambridge University Press: 10 August 2009
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of symbols and units
- List of abbreviations and acronyms
- 1 Introduction to electrochromism
- 2 A brief history of electrochromism
- 3 Electrochemical background
- 4 Optical effects and quantification of colour
- 5 Kinetics of electrochromic operation
- 6 Metal oxides
- 7 Electrochromism within metal coordination complexes
- 8 Electrochromism by intervalence charge-transfer coloration: metal hexacyanometallates
- 9 Miscellaneous inorganic electrochromes
- 10 Conjugated conducting polymers
- 11 The viologens
- 12 Miscellaneous organic electrochromes
- 13 Applications of electrochromic devices
- 14 Fundamentals of device construction
- 15 Photoelectrochromism
- 16 Device durability
- Index
- Plate Section
- References
Summary
Introduction
Systems that change colour electrochemically, but only on being illuminated, are termed photoelectrochromic (cf. electrochromic or photochromic when only one of these stimuli is applied). Relatively few photoelectrochromic systems have been examined as such, although in some studies of photoelectrochemistry, colour changes are mentioned; see refs. 1, 2, 3. One study calls such devices ‘user controllable photochromic devices’.
Few reviews of the topic are extant: the chapter on photoelectrochromism in our 1995 book is dated, but still the most comprehensive. Others include ‘Photoelectrochromic cells and their applications’ by Gregg (of NREL in Colorado) in 1997, and ‘All-polymeric electrochromic and photoelectrochemical devices: new advances’ by De Paoli et al. in 2001.
Two bases of photoelectrochromic operation are available. In the first, the potential required to evoke electrochromism is already applied but can act only through a photo-activated switch, filter or trigger. A separate photoconductor or other photocell serves as a switch, or the actual electrochromic electrode surface itself could be a photoconductor, or sandwiched together with a photoconductor. Such photo-activated systems contrast with photo-driven devices, in which illumination of one or other part of the circuit produces the photovoltaic potential required to drive the electrochromic current.
Direction of beam
The direction of illumination during cell operation is important. If the incident beam traverses a (minimum) distance in the cell prior to striking the photoactive layer, then illumination is said to be ‘front-wall’, as shown by arrow (a) in Figure 15.1.
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- Information
- Electrochromism and Electrochromic Devices , pp. 433 - 442Publisher: Cambridge University PressPrint publication year: 2007