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. For example, an OLED is disclosed that includes: 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 first electrode; and a transparent second electrode provided over the organic emissive layer, where the grid layer scatters trapped waveguided modes from the organic emissive layer.

We claim: 
     
         1 . 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 first 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.   
     
     
         2 . The OLED of  claim 1 , wherein the two optically transparent materials forming the grid layer are SiO 2  and TiO 2 . 
     
     
         3 . The OLED of  claim 1 , wherein the grid layer is electrically conductive, and can be configured as part of the first electrode or as an extension of the first electrode. 
     
     
         4 . The OLED of  claim 1 , wherein the reflective layer is a metal layer. 
     
     
         5 . The OLED of  claim 1 , wherein the reflective layer is positioned at least 100 nm from the organic emissive layer and inhibits excitation of surface plasmon polaritons. 
     
     
         6 . The OLED of  claim 1 , 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. 
     
     
         7 . The OLED of  claim 1 , further comprising an optical diffuser layer provided on the second electrode layer. 
     
     
         8 . The OLED of  claim 7 , wherein the optical diffuser layer comprises a microlens array or a nanoparticle diffuser.