Multilayer structures as stable hole-injecting electrodes for use in high efficiency organic electronic devices

Abstract

Multilayer anode structures ( 104 ) for electronic devices ( 100 ) such as polymer light-emitting diodes are described. The multilayer anodes include a high conductivity organic layer ( 114 ) adjacent to the photoactive layer ( 102 ) and a low conductivity organic layer ( 112 ) between the high conductivity organic layer and the anode's electrical connection layer ( 110 ). This anode structure provides polymer light emitting diodes which exhibit high brightness, high efficiency and long operating lifetime. The multilayer anode structure of this invention provides sufficiently high resistivity to avoid cross-talk in passively addressed pixellated polymer emissive displays; the multilayer anode structure of this invention simultaneously provides long lifetime for pixellated polymer emissive displays.

What is claimed is:  
     
         1 . A multilayer electrode comprising a first layer having a first layer conductivity, a second layer in contact with the first layer, said second layer comprising a conductive organic material having a second layer conductivity, and a third layer in contact with the second layer, said third layer comprising a conductive organic material having a third layer conductivity greater than the second layer conductivity and less than the first layer conductivity.  
     
     
         2 . A pixellated display comprising the multilayer electrode of  claim 1 .  
     
     
         3 . The multilayer electrode of  claim 1 , wherein the second layer has a bulk conductivity of from 10 −4  S/cm to 10 −11  S/cm and wherein the bulk conductivity of the third layer is from about 5 times to about 10 6  times as great as the conductivity of the second layer.  
     
     
         4 . The multilayer electrode of  claim 1 , wherein said second layer comprises a blend of conjugated conductive organic polymer with nonconductive polymer.  
     
     
         5 . The multilayer electrode of  claim 1 , wherein the second layer comprises a blend of PANI with nonconductive polymer.  
     
     
         6 . The multilayer electrode of  claim 1 , wherein the conductance of the second layer in combination with the third layer is from 1.25 to about 20 times the conductivity of the second layer alone.  
     
     
         7 . The multilayer electrode of  claim 1 , wherein the first layer comprises indium-tin oxide, the second layer comprises a water-soluble PANI blend, and the third layer comprises a poly(ethylenedioxythiophene).  
     
     
         8 . The array of  claim 1  wherein the second layer has a thickness of from about 500 Å to about 5000 Å.  
     
     
         9 . The array of  claim 1  wherein the third layer has a thickness of from about 2 Åto about 400 Å.  
     
     
         10 . The array of  claim 1  wherein said second layer comprises a mixture of conjugated conductive organic polymer with a nonconductive host polymer.  
     
     
         11 . An electronic device comprising a photoactive layer between a cathode and an anode, wherein the anode is a multilayer anode including a first anode layer comprising high conductivity transparent inorganic contact layer, a second anode layer adjacent to the first anode layer, said second anode layer comprising conjugated conductive organic polymer and having a low conductivity and a third anode layer between said second anode layer and said photoactive layer, said third anode layer comprising a conductive organic polymer and having a higher conductivity resistance than said second anode layer.  
     
     
         12 . The device of  claim 11 , wherein the cathode comprises a first cathode layer of low work function material and a second layer of electron transport/injection material between the photoactive layer and the first cathode layer, the first anode layer having anode work function and the low work function material having a cathode work function such that the anode work function is higher than the cathode work function.  
     
     
         13 . The device of  claim 11 , wherein said second layer comprises a blend of conjugated conductive organic polymer with nonconductive polymer.  
     
     
         14 . The device of  claim 11 , wherein the second layer comprises a blend of PANI with nonconductive polymer.  
     
     
         15 . The device of  claim 11 , wherein the second layer has a bulk conductivity of from 10 −4  S/cm to 10 −11  S/cm and wherein the bulk conductivity of the third layer is from about 5 times to about 10 6  times as great as the conductivity of the second layer.  
     
     
         16 . The device of  claim 11  wherein the conductance of the second layer in combination with the third layer is from 1.25 to about 20 times the conductivity of the second layer alone.  
     
     
         17 . The device of  claim 11  wherein the photoactive layer comprises a poly(phenylenevinylene)-based polymer, the cathode comprises an alkaline earth metal and the anode comprises a indium-tin oxide first layer, a water-soluble PANI blend second layer and a poly(ethylenedioxythiophene) third layer.  
     
     
         18 . The device of  claim 11 , wherein the photoactive layer comprises an active material is selected from asanthracene, butadienes, coumarin derivatives, acridine, stilbene derivatives, and combinatios thereof.  
     
     
         19 . The device of  claim 11 , wherein the photoactive layer a conjugated polymer active material.  
     
     
         20 . An array of polymer emissive diodes comprising an active emissive polymer layer having a first side in contact with a patterned cathode and a second side in contact with a patterned transparent anode, the patterning of said anode and cathode defining an array of emissive diodes, wherein a multilayer anode including a first layer comprising a patterned high conductivity inorganic contact layer, a nonpatterned second layer in contact with said first layer, said second layer comprising conjugated conductive organic polymer and having a high resistance and a nonpatterned transparent third layer in contact with said second layer and with said active emissive polymer layer, said third layer comprising a conductive organic polymer and having a lower resistance than said second layer.  
     
     
         21 . The array of  claim 20  wherein said second layer comprises a blend of conjugated conductive organic polymer with nonconductive polymer.  
     
     
         22 . The array of  claim 20  wherein said blend is a dispersion of one polymer in the other.  
     
     
         23 . The array of  claim 20  wherein said blend is a solution of one polymer in the other.  
     
     
         24 . The array of  claim 20  wherein the diode of  claim 2  wherein the second layer comprises a blend of PANI with nonconductive polymer.  
     
     
         25 . The array of  claim 24  wherein the diode of  claim 2  wherein the second layer has a bulk conductivity of from 10 −4  S/cm to 10 −11  S/cm and wherein the bulk conductivity of the third layer is from about 5 times to about 10 6  times as great as the conductivity of the second layer.  
     
     
         26 . The array of  claim 25  wherein the conductance of the second layer in combination with the third layer is from 1.25 to about 20 times the conductivity of the second layer alone.  
     
     
         27 . The array of  claim 20  wherein said patterned high conductivity transparent inorganic contact layer is present on a support.  
     
     
         28 . The array of  claim 25  wherein the second layer has a thickness of from about 500 Å to about 5000 Å.  
     
     
         29 . The array of  claim 25  wherein the third layer has a thickness of from about 2 Å to about 400 Å.  
     
     
         30 . The array of  claim 23  wherein said second layer comprises a mixture of conjugated conductive organic polymer with a nonconductive host polymer.