Polarized light sources and methods for making the same

Abstract

The disclosed invention is a novel polarized light source. The polarized light source of this invention includes an organic electroluminescent (OEL) device or an organic photoluminescent (PL) device and a cholesteric liquid crystal (CLC) polarizing device. The polarized light source of the present invention is an efficient, high purity, and bright source of polarized light. Further, the present invention enables a polarized light source to be custom designed with a polarization bandwidth and position across a wide range of wavelengths. Further still, the light source of this invention is made from low cost materials and is easily manufactured. Yet further still, this invention enables the production of ultra-thin and lightweight polarized light sources.

What we claim is:  
     
         1 . A polarized light source comprising: 
 a cholesteric liquid crystal polarizing device; and    an unpolarized light source, said unpolarized light source being a member of the group consisting of an organic electroluminescent device and an organic photoluminescent device.    
     
     
         2 . The polarized light source of  claim 1 , wherein said unpolarized light source is an organic electroluminescent device.  
     
     
         3 . The polarized light source of  claim 2 , wherein said organic electroluminescent device comprises a cathode layer superposed with an organic electroluminescent material layer which is further superposed with an anode layer.  
     
     
         4 . The polarized light source of  claim 3 , wherein said anode layer is an indium tin oxide layer.  
     
     
         5 . The polarized light source of  claim 1 , wherein said unpolarized light source is an organic photoluminescent device.  
     
     
         6 . The polarized light source of  claim 5 , wherein said organic photoluminescent device comprises a mirror superposed with an organic photoluminescent material layer.  
     
     
         7 . The polarized light source of  claim 3 , wherein said organic electroluminescent device is superposed with said cholesteric liquid crystal polarizing device.  
     
     
         8 . The polarized light source of  claim 7 , wherein said anode layer is disposed on said cholesteric liquid crystal polarizing device.  
     
     
         9 . The polarized light source of  claim 7 , wherein said cholesteric liquid crystal polarizing device is disposed on a transparent substrate.  
     
     
         10 . The polarized light source of  claim 9 , wherein said anode layer is indium tin oxide and said transparent substrate is glass.  
     
     
         11 . The polarized light source of  claim 3 , wherein a transparent substrate is disposed between said organic electroluminescent device and said cholesteric liquid crystal polarizing device.  
     
     
         12 . The polarized light source of  claim 11 , wherein said cholesteric liquid crystal polarizing device is disposed on another transparent substrate.  
     
     
         13 . The polarized light source of  claim 6 , wherein said organic photoluminescent device is superposed with said cholesteric liquid crystal polarizing device.  
     
     
         14 . The polarized light source of  claim 13 , wherein said photoluminescent material layer is disposed between said mirror and said cholesteric liquid crystal polarizing device.  
     
     
         15 . The polarized light source of  claim 14 , wherein said cholesteric liquid crystal polarizing device is disposed on a transparent substrate.  
     
     
         16 . The polarized light source of  claim 6 , wherein a transparent substrate is disposed between said organic photoluminescent device and said cholesteric liquid crystal polarizing device.  
     
     
         17 . The polarized light source of  claim 16 , wherein said cholesteric liquid crystal polarizing device is disposed on another transparent substrate.  
     
     
         18 . The polarized light source of  claim 3 , further comprising a microcavity from which microcavity resonance may be achieved, said microcavity having a microcavity length.  
     
     
         19 . The polarized light source of  claim 18 , further comprising a birefringent retarder layer, said birefringent retarder layer being disposed in said microcavity.  
     
     
         20 . The polarized light source of  claim 19 , wherein said birefringent retarder layer is disposed between said organic electroluminescent device and said cholesteric liquid crystal polarizing device.  
     
     
         21 . The polarized light source of  claim 20 , wherein said microcavity length is the optical path-length from said cathode, through said organic electroluminescent material, said anode layer and said birefringent retarder layer, to said cholesteric liquid crystal polarizing device.  
     
     
         22 . The polarized light source of  claim 20 , wherein said cholesteric liquid crystal polarizing device is disposed on a transparent substrate.  
     
     
         23 . The polarized light source of  claim 22 , wherein said anode layer is indium tin oxide and said transparent substrate is glass.  
     
     
         24 . The polarized light source of  claim 6 , further comprising a microcavity from which microcavity resonance may be achieved, said microcavity having a microcavity length.  
     
     
         25 . The polarized light source of  claim 24 , further comprising a birefringent retarder layer, said birefringent retarder layer disposed in said microcavity.  
     
     
         26 . The polarized light source of  claim 25 , wherein said birefringent retarder layer is disposed between said organic photoluminescent device and said cholesteric liquid crystal polarizing device.  
     
     
         27 . The polarized light source of  claim 26 , wherein said microcavity length is the optical path-length from said cathode, through said organic photoluminescent material and said birefringent retarder layer, to said cholesteric liquid crystal polarizing device.  
     
     
         28 . The polarized light source of  claim 26 , wherein said cholesteric liquid crystal polarizing device is disposed on a transparent substrate.  
     
     
         29 . A polarized light source comprising a member of the group consisting of an organic electroluminescent device, said organic electroluminescent device including a mixture of a cholesteric liquid crystal material and an organic electroluminescent material, and an organic photoluminescent device, said photoluminescent device including a mixture of a cholesteric liquid crystal material and an organic photoluminescent material.  
     
     
         30 . The polarized light source of  claim 29 , wherein said organic electroluminescent device further includes a cathode and an anode layer.  
     
     
         31 . The polarized light source of  claim 30 , wherein said cholesteric liquid crystal material is further mixed with a conducting polymer, said conducting polymer being a member of the group comprising poly(para-phenylene vinylene); poly(N-vinyl-carbazole); 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole; 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophen; triphenyldiamine; tris-(8-hydroxyquinoline); mixtures thereof, and the like.  
     
     
         32 . The polarized light source of  claim 30 , wherein said cholesteric liquid crystal material is bipolar.  
     
     
         33 . The polarized light source of  claim 30  wherein said cholesteric liquid crystal material has a constant pitch.  
     
     
         34 . The polarized light source of  claim 33 , further comprising a cholesteric liquid crystal polarizing device superposed with said organic electroluminescent device.  
     
     
         35 . The polarized light source of  claim 33 , wherein said anode layer is disposed on a transparent substrate.  
     
     
         36 . The polarized light source of  claim 35 , wherein said anode layer is indium tin oxide and said transparent substrate is glass.  
     
     
         37 . The polarized light source of  claim 35 , wherein said transparent substrate is disposed on a cholesteric liquid crystal polarizing device, said cholesteric liquid crystal polarizing device being disposed on another transparent substrate.  
     
     
         38 . The polarized light source of  claim 30 , wherein said cholesteric liquid crystal material has a pitch distribution.  
     
     
         39 . The polarized light source of  claim 38 , further comprising a broadband cholesteric liquid crystal polarizing device superposed with said organic electroluminescent device.  
     
     
         40 . The polarized light source of  claim 39 , wherein said broadband cholesteric liquid crystal polarizing device is disposed between two transparent substrates, said anode layer being disposed on one of said transparent substrates.  
     
     
         41 . The polarized light source of  claim 29 , wherein said organic photoluminescent device further comprises a mirror.  
     
     
         42 . The polarized light source of  claim 41  wherein said cholesteric liquid crystal material has a constant pitch.  
     
     
         43 . The polarized light source of  claim 42 , further comprising a cholesteric liquid crystal polarizing device superposed with said organic photoluminescent device.  
     
     
         44 . The polarized light source of  claim 42 , wherein said organic photoluminescent device is disposed on a transparent substrate.  
     
     
         45 . The polarized light source of  claim 44 , wherein said transparent substrate is disposed on a cholesteric liquid crystal polarizing device, said cholesteric liquid crystal polarizing device being disposed on another transparent substrate.  
     
     
         46 . The polarized light source of  claim 41 , wherein said cholesteric liquid crystal material has a pitch distribution.  
     
     
         47 . The polarized light source of  claim 46 , further comprising a broadband cholesteric liquid crystal polarizing device superposed with said organic photoluminescent device.  
     
     
         48 . The polarized light source of  claim 47 , wherein said broadband cholesteric liquid crystal polarizing device is disposed between two transparent substrates, said organic photoluminescent device being disposed between the said substrates.  
     
     
         49 . A method for fabricating a polarized light source, said method comprising: 
 (a) providing an unpolarized light source selected from the group consisting of an organic electroluminescent device and an organic photoluminescent device; and    (b) superposing the unpolarized light source with a cholesteric liquid crystal polarizing device.    
     
     
         50 . The method of  claim 49 , wherein said organic electroluminescent device includes a cathode, an organic electroluminescent material and an indium tin oxide anode layer.  
     
     
         51 . The method of  claim 49 , wherein said organic photoluminescent device includes a mirror and an organic photoluminescent material.  
     
     
         52 . The method of  claim 49 , said method further comprising: 
 (c) providing a microcavity, said microcavity including a birefringent retarder disposed therein.    
     
     
         53 . A method for fabricating a polarized light source, said method comprising: 
 (a) preparing a material mixture, said material mixture including a cholesteric liquid crystal material and a member of the group consisting of an organic electroluminescent material and an organic photoluminescent material; and    (b) incorporating said material mixture into a light source, said light source being a member of the group consisting of an organic electroluminescent device and an organic photoluminescent device.    
     
     
         54 . The method of  claim 53 , wherein said cholesteric liquid crystal material has a constant pitch.  
     
     
         55 . The method of  claim 54 , further comprising: 
 (c) superposing said light source with a cholesteric liquid crystal polarizing device.    
     
     
         56 . The method of  claim 53 , wherein said cholesteric liquid crystal material has a pitch distribution.  
     
     
         57 . The method of  claim 56 , further comprising: 
 (c) superposing said light source with a broadband cholesteric liquid crystal polarizing device.    
     
     
         58 . A polarized light source comprising: 
 a cholesteric liquid crystal polarizing means; and    means for providing an unpolarized light source, said means for providing an unpolarized light source being a member of the group consisting of an organic electroluminescent device and an organic photoluminescent device.