ELECTROCHROMIC DEVICE CONTAINING DISTRIBUTED BRAGG REFLECTOR CONFIGURED TO SELECTIVELY REFLECT UV RADIATION
An electrochromic device and method, the device including a light transmissive first substrate, a working electrode disposed on the first substrate, a counter electrode, a solid state electrolyte layer disposed between the counter electrode and the working electrode, a light transmissive second substrate disposed on the counter electrode, and a Bragg reflector configured to selectively reflect UV radiation away from the working electrode.
1 . An electrochromic device, comprising:
a light transmissive first substrate;
a working electrode disposed over the first substrate;
a counter electrode;
a solid state electrolyte layer disposed between the counter electrode and the working electrode;
a light transmissive second substrate disposed over the counter electrode; and
a Bragg reflector configured to selectively reflect UV radiation away from the working electrode.
2 . The electrochromic device of claim 1 , wherein the Bragg reflector comprises:
first layers having a first index of refraction; and
second layers alternately stacked with the first layers and having a second index of refraction that is different than the first index of refraction.
3 . The electrochromic device of claim 2 , wherein:
the first layers comprise TiO 2 ; and
the second layers comprise SiO 2 .
4 . The electrochromic device of claim 2 , wherein the first layers and the second layers comprise different materials selected from TiO 2 , SiO 2 , ZnO x , ZnAlO x , and ZnSnO x .
5 . The electrochromic device of claim 1 , further comprising a first transparent conductor disposed between the Bragg reflector and the working electrode.
6 . The electrochromic device of claim 1 , further comprising a second transparent conductor disposed between the Bragg reflector and the working electrode.
7 . The electrochromic device of claim 1 , further comprising:
a first transparent conductor disposed between the working electrode and the first substrate; and
a second transparent conductor disposed between the counter electrode and the second substrate.
8 . The electrochromic device of claim 7 , wherein the Bragg reflector is disposed between the first substrate and the first transparent conductor.
9 . The electrochromic device of claim 7 , wherein the Bragg reflector is disposed between the second substrate and the second transparent conductor.
10 . The electrochromic device of claim 1 , wherein the Bragg reflector is configured to:
transmit at least 50% of visible light incident thereto; and
reflect at least 50% of UV radiation incident thereto.
11 . The electrochromic device of claim 1 , wherein the solid state electrolyte layer comprises:
a polymer; and
at least one of lithium ions, sodium ions, and potassium ions.
12 . The electrochromic device of claim 1 , wherein the working electrode comprises transition metal oxide nanostructures.
13 . The electrochromic device of claim 12 , wherein the nanostructures comprise cesium doped tungsten oxide cubic nanoparticles and amorphous niobium oxide nanoparticles.
14 . The electrochromic device of claim 12 , wherein the nanostructures comprise doped or undoped tungsten oxide hexagonal nanoparticles.
15 . The electrochromic device of claim 12 , wherein the counter electrode layer comprises cerium oxide nanoparticles and indium oxide nanoparticles.
16 . The electrochromic device of claim 1 , wherein the counter electrode layer comprises one or more of the following components:
a passive electrode material selected from one or more cerium(IV) oxide (CeO 2 ), titanium dioxide (TiO 2 ), cerium(III) vanadate (CeVO 2 ), indium(III) oxide (In 2 O 3 ), tin-doped indium oxide, tin(II) oxide (SnO 2 ), manganese-doped tin oxide, antimony-doped tin oxide, zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), iron(III) oxide (Fe 2 O 3 ), and vanadium(V) oxide (V 2 O 5 );
an active electrode material selected from chromium(III) oxide (Cr 2 O 3 ), manganese dioxide (MnO 2 ), iron(II) oxide (FeO), cobalt oxide (CoO), nickel(II) oxide (NiO), rhodium(IV) oxide (RhO 2 ), and iridium(IV) oxide (IrO 2 );
amorphous nickel oxide nanoparticles and/or web; and
conductivity enhancer nanoparticles selected from indium oxide, ITO, and zinc oxide.
17 . The electrochromic device of claim 1 , wherein the first and second substrates comprise opposing window panes.
18 . The electrochromic device of claim 17 , wherein the first and second substrates comprise opposing glass window panes.
19 . The electrochromic device of claim 1 , wherein:
the Bragg reflector is disposed between the first substrate and the first transparent conductor; and
the electrochromic device further comprises an additional Bragg reflector disposed between the second substrate and the second transparent conductor.
20 . A method of operating an electrochromic device comprising a working electrode, a counter electrode, a solid state electrolyte layer disposed between the counter electrode and the working electrode, and a Bragg reflector, the method comprising:
operating the electrochromic device in a bright mode, such that the electrochromic device transmits at least 50% of received visible light; and
operating the electrochromic device in a dark mode, such that the electrochromic device transmits 5% or less of received visible light, wherein the Bragg reflector selectively reflects a majority of UV radiation and transmits a majority of received visible light.
21 . The method of claim 20 , wherein the Bragg reflector transmits at least about 90% of visible light incident thereto and reflects at least about 90% of UV radiation incident thereto.
22 . The method of claim 20 , wherein:
the operating the electrochromic device in the dark mode comprises applying a voltage between the working electrode and the counter electrode; and
the operating the electrochromic device in the bright mode comprises applying a substantially zero voltage between the working electrode and the counter electrode.