Organic light-emitting diode display device

Abstract

An display device including a substrate, an organic light-emitting diode, and a thin film encapsulation layer. The organic light-emitting diode is disposed on the substrate. The thin film encapsulation layer is disposed on the organic light-emitting diode. The thin film encapsulation layer includes at least one inorganic layer, at least one organic layer, and a first refractive-index control layer. The at least one organic layer is alternately disposed with the at least one inorganic layer. The first refractive-index layer is disposed between one of the at least one inorganic layer and one of the at least one organic layer disposed adjacent to each other. The first refractive-index control layer has a refractive-index variation ratio per unit length (Δn/nm) from about 0.001/nm to about 0.002/nm along a direction from the organic light-emitting diode toward the thin film encapsulation layer.

What is claimed is: 
     
         1 . A display device, comprising:
 a substrate;   an organic light-emitting diode disposed on the substrate; and   a thin film encapsulation layer disposed on the organic light-emitting diode,   wherein the thin film encapsulation layer comprises:   at least one inorganic layer;   at least one organic layer alternately disposed with the at least one inorganic layer; and   a first refractive-index control layer disposed between one of the at least one inorganic layer and one of the at least one organic layer disposed adjacent to each other,   wherein the first refractive-index control layer has a refractive-index variation ratio per unit length (Δn/nm) from about 0.001/nm to about 0.002/nm along a direction from the organic light-emitting diode toward the thin film encapsulation layer.   
     
     
         2 . The display device of  claim 1 , wherein the first refractive-index control layer has a refractive index from about 1.5 to about 1.8. 
     
     
         3 . The display device of  claim 1 , wherein the first refractive-index control layer has a refractive index gradually decreasing along a direction from the at least one inorganic layer toward the at least one organic layer. 
     
     
         4 . The display device of  claim 1 , wherein the first refractive-index control layer comprises:
 a first surface facing the at least one inorganic layer; and   a second surface facing the at least one organic layer, wherein   the first surface has a higher refractive index than a refractive index of the second surface by about 0.1 to about 0.3.   
     
     
         5 . The display device of  claim 1 , wherein the first refractive-index control layer has a thickness of from about 100 nm to about 250 nm. 
     
     
         6 . The display device of  claim 1 , wherein the first refractive-index control layer comprises:
 at least one low refractive-index material including silicon oxide, magnesium fluoride, acrylic polymer, polyimide, polyamide, or Alq 3 [Tris(8-hydroxyquinolinato)aluminium]; and   at least one high refractive-index material including zinc oxide, titanium oxide, zirconium oxide, niobium oxide, tantalum oxide, tin oxide, nickel oxide, silicon nitride, indium nitride, gallium nitride, poly(3,4-ethylenedioxythiophene) (PEDOT), 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD), 4,4′,4″-tris [(3-methylphenyl)phenylamino] triphenylamine (m-MTDATA), 1,3,5-tris [N,N-bis(2-methylphenyl)-amino]benzene (o-MTDAB), 1,3,5-tris[N,N-bis(3-methylphenyl)-amino]benzene (m-MTDAB), 1,3,5-tris [N,N-bis (4-methylphenyl)amino]benzene (p-MTDAB), 4,4′-bis[N,N-bis(3-methylphenyl)-amino] diphenylmethane (BPPM), 4,4-dicarbazolyl-1,1′-biphenyl (CBP), 4,4′,4″-tris(N-carbazole) triphenylamine (TCTA), 2,2′,2″-(1,3,5-benzenetolyl)tris-[1-phenyl-1H-benzoimidazol] (TPBI), or 3-(4-biphenyl)-4-phenyl-5-t-butylphenyl-1,2,4-triazole (TAZ).   
     
     
         7 . The display device of  claim 1 , wherein the first refractive-index control layer comprises:
 a first matching layer disposed on the inorganic layer; and   a second matching layer disposed on the first matching layer.   
     
     
         8 . The display device of  claim 7 , wherein the first matching layer and the second matching layer have a refractive-index difference from about 0.05 to about 0.1. 
     
     
         9 . The display device of  claim 7 , wherein the first matching layer has a higher refractive index than a refractive index of the second matching layer by about 0.05 to about 0.1. 
     
     
         10 . The display device of  claim 7 , further comprising a third matching layer disposed on the second matching layer, wherein the third matching layer has a lower refractive index than a refractive index of the second matching layer. 
     
     
         11 . The display device of  claim 7 , wherein each of the first matching layer and the second matching layer has a thickness of from about 25 nm to about 60 nm. 
     
     
         12 . The display device of  claim 1 , wherein the at least one inorganic layer has a refractive index from about 1.6 to about 2.8. 
     
     
         13 . The display device of  claim 1 , wherein the at least one inorganic layer has a thickness of from about 100 nm to about 1,000 nm. 
     
     
         14 . The display device of  claim 1 , wherein the at least one organic layer has a refractive index from about 1.4 to about 1.6. 
     
     
         15 . The display device of  claim 1 , wherein the at least one organic layer has a thickness of from about 100 nm to about 8,000 nm. 
     
     
         16 . The display device of  claim 1 , further comprising a capping layer disposed between the organic light-emitting diode and the thin film encapsulation layer. 
     
     
         17 . The display device of  claim 1 , wherein the thin film encapsulation layer further comprises a second refractive-index control layer disposed opposite the first refractive-index control layer with respect to the at least one inorganic layer. 
     
     
         18 . The display device of  claim 1 , wherein the thin film encapsulation layer further comprises a third refractive-index control layer disposed opposite the first refractive-index control layer with respect to the at least one organic layer. 
     
     
         19 . The display device of  claim 1 , wherein the organic light-emitting diode comprises:
 a first electrode disposed on the substrate;   an organic light-emitting layer disposed on the first electrode; and   a second electrode disposed on the organic light-emitting layer.   
     
     
         20 . A display device, comprising:
 a substrate;   an organic light-emitting diode disposed on the substrate; and   a thin film encapsulation layer disposed on the organic light-emitting diode,   wherein the thin film encapsulation layer comprises:   at least one inorganic layer; and   at least one organic layer disposed alternately with the at least one inorganic layer,   wherein the at least one inorganic layer has a refractive index from about 1.75 to about 2.55, and   wherein one of the at least one inorganic layer and one of the at least one organic layer have a refractive-index difference of about 0.15 or less.   
     
     
         21 . The display device of  claim 20 , wherein the at least one inorganic layer and the at least one organic layer have a refractive-index difference of about 0.06 or less. 
     
     
         22 . The display device of  claim 20 , wherein the at least one organic layer comprises:
 poly(3,4-ethylenedioxythiophene) (PEDOT), 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD), 4,4′,4″-tris[(3-methylphenyl)phenylamino] triphenylamine (m-MTDATA), 1,3,5-tris [N,N-bis(2-methylphenyl)-amino]benzene (o-MTDAB), 1,3,5-tris[N,N-bis(3-methylphenyl)-amino]benzene (m-MTDAB), 1,3,5-tris [N,N-bis (4-methylphenyl)amino]benzene (p-MTDAB), 4,4′-bis[N,N-bis(3-methylphenyl)-amino] diphenylmethane (BPPM), 4,4-dicarbazolyl-1,1′-biphenyl (CBP), 4,4′,4″-tris(N-carbazole) triphenyl amine (TCTA), 2,2′,2″-(1,3,5-benzenetolyl)tris-[1-phenyl-1H-benzoimidazol] (TPBI), or 3-(4-biphenyl)-4-phenyl-5-t-butylphenyl-1,2,4-triazole (TAZ).   
     
     
         23 . The display device of  claim 20 , wherein the thin film encapsulation layer has a thickness of about 50 μm or less. 
     
     
         24 . The display device of  claim 20 , wherein the at least one inorganic layer has a thickness of from about 100 nm to about 1,000 nm. 
     
     
         25 . The display device of  claim 20 , wherein the at least one inorganic layer includes silver, metal oxide, metal oxynitride, silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof.