Chromogenic Applications

The term chromogenic originated from the Greek word chromo that means color, and is commonly used when referring to the study and use of materials that show a reversible change in their optical properties when they are subjected to certain ambient conditions and different external stimuli, such as light, electric field, heat, humidity, gas exposure, and pressure. In this chapter the importance and unique performance of the transition metal oxide nanostructures that show chromogenic behavior, such as WO3, NiO, TiO2, VO2, and many others, when thermal-, electrical-, light-, or humidity-stimulated, are emphasized. The state of the art when referring to applications of this type of materials is illustrated, with a brief historical introduction and the physical and chemical working principles of different chromogenic effects.