355
conductive layers are often indium tin oxide. As noted, one layer
is coated with an electrochromic film and the other with an ion
storage film. Both of these films must have some level of porosity. The porosity is important in facilitating the needed movement
of ions in and out of the material. Current approaches to porosity
vary. It appears that the use of nanomaterials in relation to very specific levels of nanoporosity can improve performance. Important
nanotechnology considerations include not only material types but
the kinds of synthesis processes (see Chapter 8) that can be used
to impart needed porosities and layer thicknesses. Many types of
processes, such as sputter deposition, have already been used
successfully.
luminescence
Many light-emitting technologies that can benefit from the use
of nanomaterials are ultimately based on the luminescence qualities of many materials (see Section 4.7). This light-emitting quality
is not based on incandescence (visible radiation associated with
a thermally hot glowing body) but is rather based on other types
of excitation by other energy sources such as a chemical reaction
(as can be observed in the common “light stick” so prevalently
seen during Halloween). Fluorescence is a form of luminescence
wherein the light is more or less instantly emitted when the material is excited, as in the common fluorescent light. Phosphorescence occurs when the light is emitted more slowly over time (and
can still have a decayed afterglow when the excitation source is
removed). In all cases, energy is absorbed by the material and
subsequently reemitted as light. Various colors can be produced
by varying the nature of the material, particularly the impurities
within it. Depending on the energy excitation source, various lightemitting technologies are commonly classified as being primarily
chemoluminescent, electroluminescent, or photoluminescent, although
light can be emitted because of other energy mechanisms (such
as friction) as well.
nanophosphors in lighting
Various kinds of phosphors are already commonly used in many
lighting devices, including common fluorescent tubes, electroluminescent wires, strips and surfaces, and LEDs. In a ubiquitous fluorescent tube, the inside is coated with phosphors. Electricity excites
the gas-filled tube to produce shortwave light, which in turn causes
the phosphors to become fluorescent and produce visible light. In
Light and Optical Environments
conductive layers are often indium tin oxide. As noted, one layer
is coated with an electrochromic film and the other with an ion
storage film. Both of these films must have some level of porosity. The porosity is important in facilitating the needed movement
of ions in and out of the material. Current approaches to porosity
vary. It appears that the use of nanomaterials in relation to very specific levels of nanoporosity can improve performance. Important
nanotechnology considerations include not only material types but
the kinds of synthesis processes (see Chapter 8) that can be used
to impart needed porosities and layer thicknesses. Many types of
processes, such as sputter deposition, have already been used
successfully.
luminescence
Many light-emitting technologies that can benefit from the use
of nanomaterials are ultimately based on the luminescence qualities of many materials (see Section 4.7). This light-emitting quality
is not based on incandescence (visible radiation associated with
a thermally hot glowing body) but is rather based on other types
of excitation by other energy sources such as a chemical reaction
(as can be observed in the common “light stick” so prevalently
seen during Halloween). Fluorescence is a form of luminescence
wherein the light is more or less instantly emitted when the material is excited, as in the common fluorescent light. Phosphorescence occurs when the light is emitted more slowly over time (and
can still have a decayed afterglow when the excitation source is
removed). In all cases, energy is absorbed by the material and
subsequently reemitted as light. Various colors can be produced
by varying the nature of the material, particularly the impurities
within it. Depending on the energy excitation source, various lightemitting technologies are commonly classified as being primarily
chemoluminescent, electroluminescent, or photoluminescent, although
light can be emitted because of other energy mechanisms (such
as friction) as well.
nanophosphors in lighting
Various kinds of phosphors are already commonly used in many
lighting devices, including common fluorescent tubes, electroluminescent wires, strips and surfaces, and LEDs. In a ubiquitous fluorescent tube, the inside is coated with phosphors. Electricity excites
the gas-filled tube to produce shortwave light, which in turn causes
the phosphors to become fluorescent and produce visible light. In
Light and Optical Environments