Nanostructured OLED Cathode Light Extraction via Scatterer Lattices
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Solution Overview
Problem
Current organic light-emitting diodes (OLEDs) face challenges in enhancing light-extraction efficiency and spontaneous-emission rates, particularly in nanostructured, white-emitting OLEDs operating under broad spectral bandwidth and isotropic emitters, where existing designs fail to effectively couple light out of the device.
Innovation Solution
A nanostructured OLED design featuring a two-dimensionally periodic lattice of nanoscale scatterers with limited disorder at the metal-cathode surface, which enhances coupling to surface-plasmon polaritons and radiatively scatters non-radiative modes, improving light-extraction efficiency and spontaneous-emission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional OLED designs are used, then device simplicity is maintained, but light-extraction efficiency is insufficient
Solution Approach 1:
The patent applies nanoscale texturing to create a porous-like surface structure on the electrode. The surface is modified with nanoscale features (protrusions and recesses) that increase the effective surface area and create multiple scattering interfaces, analogous to porous materials, thereby enhancing light extraction without adding complex bulk structures
Solution Approach 2:
The patent transitions from a planar 2D electrode surface to a 3D nanoscale textured surface. By introducing vertical dimensionality through nanoscale protrusions and recesses, the design creates additional light-matter interaction pathways and scattering centers that improve extraction efficiency while maintaining overall device simplicity
2Ease of manufacture
If smooth electrode surfaces are used, then manufacturing is easier, but spontaneous-emission rates are limited
Solution Approach 1:
The patent modifies the surface parameter of the electrode by introducing nanoscale roughness characteristics. The surface is transformed from smooth to nanoscale textured, changing the physical parameters (surface area, scattering properties, local field enhancement) that govern spontaneous emission rates, thereby enabling higher emission efficiency
3Loss of energy
If nanoscale texturing is applied to enhance light extraction, then light-extraction efficiency improves, but device complexity increases
Solution Approach 1:
The patent employs nanoscale curved features (protrusions and recesses) on the electrode surface. These curved nanoscale structures provide effective light scattering and trapping while being potentially manufacturable through established nanofabrication techniques, balancing performance enhancement with manufacturing feasibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively extracts light over a broad bandwidth, increasing light-extraction efficiency and spontaneous-emission rates, making it suitable for solid-state lighting applications, even with limited disorder in the array.
Implementation Method 1
enhances coupling to surface-plasmon polaritons
Implementation Method 2
radiatively scatters non-radiative modes
Data Source
AI summary
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.