Enhancing light extraction of organic light emitting diodes via nanoscale texturing of electrode surfaces

• US 9,761,842 B2
• Filed: 12/21/2015
• Issued: 09/12/2017
• Est. Priority Date: 12/19/2014
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Oskooi, Ardavan, Forrest, Stephen R.
• Primary Examiner(s): Wilson, Allan R
• Application Number:
  US14/976,786
• Publication Number:
  US 20160197306A1
• Time in Patent Office: 631 Days
• CPC Class Codes: H01L 21/76817 using printing or stamping techniques
• CPC Class Codes: H10K 2101/00 Properties of the organic materials covered by group H10K85/00
• CPC Class Codes: H10K 2102/3023 Direction of light emission
• CPC Class Codes: H10K 50/822 characterised by their shape
• CPC Class Codes: H10K 50/854 comprising scattering means

Abstract

An organic light emitting device is described, having an OLED including an anode, a cathode, and at least one organic layer between the anode and cathode. At least a portion of an electrode surface includes a plurality of scattering structures positioned in a partially disordered pattern resembling nodes of a two dimensional lattice. The scattering structures are positioned around the nodes of the two dimensional lattice with the average distance between the position of each scattering structure and a respective node of the lattice is from 0 to 0.5 of the distance between adjacent lattice nodes. A method of manufacturing an organic light emitting device and a method of enhancing the light-extraction efficiency of an organic light emitting device are also described.

Claims

1. An organic light emitting device, comprising:

an OLED including an anode, a cathode, and at least one organic layer between the anode and cathode;

wherein at least a portion of the cathode surface includes a plurality of scattering structures positioned in a partially disordered pattern resembling nodes of a two dimensional lattice, wherein the scattering structures are positioned around the nodes of the two dimensional lattice with the average distance between the position of each scattering structure and a respective node of the lattice is from 0 to 0.5 of the distance between adjacent lattice nodes, and wherein at least two scattering structures have a different distance between their position and their respective nodes.

2. The device of claim 1, wherein the scattering structures are on the cathode surface adjacent the at least one organic layer.

3. The device of claim 1, wherein the distance between at least two of the scattering structures is from 150 nm to 650 nm.

4. The device of claim 1, wherein at least one of the scattering structures is a protrusion.

5. The device of claim 4, wherein the at least one scattering structure protrudes into the at least one organic layer.

6. The device of claim 1, wherein at least one of the scattering structures is a recess into the cathode surface.

7. The device of claim 1, wherein the scattering structures are hemispheres.

8. The device of claim 1, wherein the device is a bottom-emitting OLED device.

9. The device of claim 1, wherein the partially disordered pattern resembles nodes of a two dimensional square lattice.

10. The device of claim 1, wherein the partially disordered pattern resembles nodes of a two dimensional periodic lattice.