Materials and Methods for OLED Microcavities and Buffer Layers

Abstract

The present teachings provide methods for forming organic layers for an organic light-emitting device (OLED) using an inkjet printing or thermal printing process. The method can further use one or more additional processes, such as vacuum thermal evaporation (VTE), to create an OLED stack. OLED stack structures are also provided wherein at least one of the charge injection or charge transport layers is formed by an inkjet printing or thermal printing method at a high deposition rate. The structure of the organic layer can be amorphous, crystalline, porous, dense, smooth, rough, or a combination thereof, depending on deposition parameters and post-treatment conditions. An OLED microcavity is also provided and can be formed by one of more of the methods.

What is claimed is: 
     
         1 . A microcavity for an organic light-emitting device, the microcavity comprising:
 a substrate comprising a first reflective electrode;   a dry film organic material layer formed on the substrate and comprising a first surface facing the substrate and a second surface opposite the first surface;   an emitting layer over the dry film organic material layer such that the dry film organic material layer is between the first reflective electrode and the emitting layer, the emitting layer comprising a light-emitting organic material that emits light, upon excitation, at a peak emission wavelength; and   a second reflective electrode over the emitting layer such that the emitting layer is between the first reflective electrode and the second reflective electrode,   wherein the second surface exhibits a surface roughness of from about 5.0 nm to about 1.0 μm as the root mean squared of surface thickness deviations in an area 10×10 μm 2 , the organic light-emitting device stack exhibits an increase in luminosity by a factor of from about 1.01 to about 2.0 relative to the luminosity of the same microcavity having a second surface with a surface roughness of less than 5.0 nm expressed as the root mean square of the surface thickness deviation in an area 10×10 μm 2 .   
     
     
         2 . The microcavity of  claim 1 , wherein the dry film organic material layer comprises from about 2 sub-layers to about 20 sub-layers. 
     
     
         3 . The microcavity of  claim 1 , wherein the dry film organic material layer comprises a baked dry film organic material layer that has been baked at a temperature of about 50° C. to about 250° C. 
     
     
         4 . The microcavity of  claim 3 , wherein the bake time at about 50° C. to about 250° C. is about 5.0 milliseconds to about 5.0 hours. 
     
     
         5 . The microcavity of  claim 1 , wherein the dry film organic material layer comprises a baked dry film organic material layer that has been baked at a temperature of about 250° C. to about 450° C. 
     
     
         6 . The microcavity of  claim 5 , wherein the bake time at about 250° C. to about 450° C. is about 5.0 milliseconds to about 5.0 hours. 
     
     
         6 . The microcavity of  claim 1 , wherein at least one of the first and second reflective electrodes is semi-transparent. 
     
     
         7 . The microcavity of  claim 1 , wherein the first reflective electrode and the second reflective electrode are separated from one another by a distance, wherein the distance corresponds to a depth of the microcavity, and the depth of the microcavity is configured for resonance emission of the peak emission wavelength. 
     
     
         8 . The microcavity of  claim 1 , wherein the dry film organic material layer comprises a crystalline baked dry film organic material layer. 
     
     
         9 . The microcavity of  claim 8 , wherein the crystalline dry film organic material layer has a conductivity of from about 1.0×10 −9  S/m to about 1.0×10 −1  S/m. 
     
     
         10 . The microcavity of  claim 1 , wherein the dry film organic material layer formed on the substrate comprises at least one of a hole injection layer, a hole transport layer, an emission layer, an electron transport layer, and an electron injection layer. 
     
     
         11 . The microcavity of  claim 1 , wherein the dry film organic material layer is formed as a printed organic material layer. 
     
     
         12 . The microcavity of  claim 11 , wherein the printed organic material layer is formed using inkjet printing. 
     
     
         13 . The microcavity of  claim 1 , wherein the emitting layer is formed as a printed emitting layer. 
     
     
         14 . The microcavity of  claim 13 , wherein the printed emitting layer is formed using inkjet printing. 
     
     
         15 . The microcavity of  claim 1 , wherein the refractive index of the substrate is from about 1.01 to about 1.55 and the refractive index of the organic material layer is from about 1.60 to about 5.01.