Variable transmittance optical filter and uses thereof

Abstract

Variable transmittance optical filters capable of transitioning from a light state to a dark state on exposure to UV radiation and from a dark state to a light state with application of an electric voltage are provided. The optical filters comprise a switching material that comprises one or more chromophores that have electrochromic and photochromic properties.

1 .- 18 . (canceled) 
     
     
         19 . An apparatus comprising:
 a switchable optical filter capable of transitioning between a light state and a dark state, wherein a light transmittance of the optical filter is greater in the light state than a light transmittance of the optical filter in the dark state, and wherein the optical filter comprises:   first and second transparent substrates;   first and second electrodes disposed on at least one of the first and second substrates; and   a switching material disposed between the first and second substrates and in contact with the first and second electrodes,   wherein a haze transmission of the optical filter is 10% or less.   
     
     
         20 . The apparatus of  claim 19 , wherein the haze transmission of the optical filter is about 5% or less. 
     
     
         21 . The apparatus of  claim 19 , wherein the optical filter has at least one intermediate state between the light state and the dark state, wherein a light transmittance of the optical filter is:
 greater in the light state than in the at least one intermediate state; and   lower in the dark state than in the at least one intermediate state, and   wherein an optical clarity of the optical filter is constant for the light state, the a least one intermediate state, and the dark state.   
     
     
         22 . The apparatus of  claim 19 , wherein an optical clarity of the optical filter is constant for all states of the optical filter between the light state and the dark state. 
     
     
         23 . The apparatus of  claim 19 , wherein the optical filter is capable of transitioning from the light state to the dark state in response to exposure to sunlight. 
     
     
         24 . The apparatus of  claim 19 , wherein the optical filter is capable of transitioning from the light state to the dark state in response to exposure to sunlight or ultraviolet radiation. 
     
     
         25 . The apparatus of  claim 19 , wherein the optical filter is capable of transitioning from the dark state to the light state in response to a voltage applied between the first and second electrodes. 
     
     
         26 . The apparatus of  claim 19 , wherein at least one of the first and second substrates is flexible. 
     
     
         27 . The apparatus of  claim 19 , wherein the switching material comprises an initiator for polymerizing and/or cross-linking the switching material. 
     
     
         28 . The apparatus of  claim 19 , wherein the switching material comprises a solvent component and one or more chromophores, and wherein solvent component is for interspersing the one or more chromophores throughout the switching material. 
     
     
         29 . The apparatus of  claim 19 , wherein the switching material is a hybrid photochromic and electrochromic switching material. 
     
     
         30 . The apparatus of  claim 29 , wherein the switching material comprises one or more chromophores selected from a group of compounds consisting of diarylethenes, dithienylcyclopentenes, and fulgides. 
     
     
         31 . The apparatus of  claim 19 , wherein in the light state the optical filter is capable of achieving a visible light transmittance of about 50% or greater. 
     
     
         32 . The apparatus of  claim 19 , wherein in the dark state the optical filter is capable of achieving a visible light transmittance of about 30% or less. 
     
     
         33 . The apparatus of  claim 19 , wherein a contrast ratio of a light transmittance of the optical filter in the light state and the dark state is greater than about 2. 
     
     
         34 . The apparatus of  claim 19 , wherein a visible light transmittance of the optical filter in the dark state does not substantially change with temperature. 
     
     
         35 . The apparatus of  claim 19 , further comprising:
 power control electronics comprising a switch for electrically coupling to a power source, the power control electronics being electrically coupled to the first and second electrodes and operable to transition the switchable optical filter from the dark state to the light state by applying a voltage from the power source across the first and second electrodes.   
     
     
         36 . A variable tint window comprising:
 a switchable optical filter capable of transitioning between a light state and a dark state, wherein a light transmittance of the optical filter is greater in the light state than a light transmittance of the optical filter in the dark state, and wherein the optical filter comprises:   first and second transparent substrates;   first and second electrodes disposed on at least one of the first and second substrates; and   a switching material disposed between the first and second substrates and in contact with the first and second electrodes,   wherein a haze transmission of the optical filter is 10% or less.   
     
     
         37 . A switchable optical filter capable of transitioning between a light state and a dark state, wherein a light transmittance of the optical filter is greater in the light state than a light transmittance of the optical filter in the dark state, and wherein the optical filter comprises:
 first and second transparent substrates;   first and second electrodes disposed on at least one of the first and second substrates; and   a switching material disposed between the first and second substrates and in contact with the first and second electrodes,   wherein the optical filter has at least one intermediate state between the light state and the dark state, wherein a light transmittance of the optical filter is:   greater in the light state than in the at least one intermediate state; and   lower in the dark state than in the at least one intermediate state, and   wherein an optical clarity of the optical filter is constant for the light state, the a least one intermediate state, and the dark state.   
     
     
         38 . The switchable optical filter of  claim 37 , wherein an optical clarity of the optical filter is constant for all states of the optical filter between the light state and the dark state.