Enhanced oled outcoupling by suppressing surface plasmon modes

Abstract

A number of new solutions for enhancing the extraction of waveguided mode and suppressing surface plasmon polariton mode in OLEDs are disclosed.

We claim: 
     
         1 . An organic light emitting device (OLED), comprising:
 a transparent substrate having a first side and a second side;   a transparent organic light scattering layer disposed over the first side of the substrate, wherein the organic light scattering layer is a continuous layer having a randomly corrugated surface texture with surface texture height between 5 nm-10 μm with a lateral feature size of 100-1000 nm; and   an emissive region disposed on the organic scattering layer, the emissive region comprising:
 a transparent anode; 
 a cathode; and 
 at least one organic emissive layer between the transparent anode and the cathode, wherein the transparent anode, the organic emissive layer, and the cathode each have a randomly corrugated structure produced by the randomly corrugated surface texture of the underlying transparent organic light scattering layer and the randomly corrugated structure in the emissive region extracts waveguided mode. 
   
     
     
         2 . The OLED of  claim 1 , wherein the surface texture height of the organic light scattering layer is between 5-500 nm. 
     
     
         3 . The OLED of  claim 1 , wherein the surface texture height of the organic light scattering layer is between 5-300 nm. 
     
     
         4 . The OLED of  claim 1 , wherein the average surface texture height of the organic light scattering layer is between 130-170 nm. 
     
     
         5 . The OLED of  claim 1 , wherein the lateral feature size of the randomly corrugated surface texture is 100 nm-10 μm. 
     
     
         6 . The OLED of  claim 1 , further comprising an optical diffuser layer provided on the second side of the transparent substrate. 
     
     
         7 . The OLED of  claim 6 , wherein the optical diffuser layer comprises a microlens array or a nanoparticle diffuser. 
     
     
         8 . The OLED of  claim 1 , wherein the emissive region further comprises an electron transport layer having a thickness of at least 30 nm but no more than 400 nm disposed between the cathode and the at least one organic emissive layer. 
     
     
         9 . A organic light emitting device (OLED), comprising:
 a transparent substrate having a first side and a second side;   an emissive region disposed over the first side of the transparent substrate, the emissive region comprising:
 a transparent first electrode disposed over the transparent substrate; 
 at least one organic emissive layer disposed over the transparent first electrode; and 
 a transparent second electrode disposed over the at least one organic emissive layer; 
   an optical grating layer having a grating structure having a sub-wavelength periodicity disposed on the transparent second electrode; and   a reflective layer disposed over the optical grating layer.   
     
     
         10 . The OLED of  claim 9 , wherein the grating structure layer has a feature size of 300 nm and a thickness of no more than 10 nm. 
     
     
         11 . The OLED of  claim 9 , further comprising an optical diffuser layer provided on the second side of the transparent substrate. 
     
     
         12 . The OLED of  claim 11 , wherein the optical diffuser layer comprises a microlens array or a nanoparticle diffuser. 
     
     
         13 . The OLED of  claim 9 , wherein the emissive region further comprises an electron transport layer having a thickness of at least 50 nm disposed between the cathode and the at least one organic emissive layer. 
     
     
         14 . A organic light emitting device (OLED), comprising:
 a substrate having a first side and a second side;   a reflective layer disposed over the first side of the substrate;   a grid layer consisting of two optically transparent materials with different refractive indices disposed on the reflective layer;   a transparent first electrode provided over the grid layer;   an organic emissive layer provided over the transparent bottom electrode; and   a transparent second electrode provided over the organic emissive layer, wherein the grid layer scatters trapped waveguided modes from the organic emissive layer.   
     
     
         15 . The OLED of  claim 14 , wherein the two optically transparent materials forming the grid layer are SiO 2  and TiO 2 . 
     
     
         16 . The OLED of  claim 14 , wherein the grid layer is electrically conductive, and provides an extension of the first electrode. 
     
     
         17 . The OLED of  claim 14 , wherein the reflective layer is a metal layer. 
     
     
         18 . The OLED of  claim 14 , wherein the reflective layer is positioned at least 100 nm from the organic emissive layer and inhibits excitation of surface plasmon polaritons. 
     
     
         19 . The OLED of  claim 14 , further comprising a spacer layer provided between the grid layer and the transparent first electrode, wherein cavity resonant frequency in the OLED can be tuned by varying the spacer layer's thickness. 
     
     
         20 . The OLED of  claim 14 , further comprising an optical diffuser layer provided on the second electrode layer. 
     
     
         21 . The OLED of  claim 20 , wherein the optical diffuser layer comprises a microlens array or a nanoparticle diffuser.