Mesh Anode OLED Reducing Interface Defects
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Solution Overview
Problem
Surface defects at the interface of the Hole Transfer Layer and ITO transparent anode in OLEDs reduce device lifetime and light emission efficiency due to light absorption by the anode.
Innovation Solution
Formation of mesh-shaped electrodes using a wet process, allowing light to pass through and reducing contact surface defects, with metal materials like Ni, Au, Ag, or Cu having a work function greater than 4.8 eV, and a process involving optical catalyst films, water-soluble polymers, and electroless plating to create metal patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent anode (ITO) is used in OLED, then light emission is enabled, but surface defects occur at the interface with the hole transfer layer reducing device lifetime
Solution Approach 1:
The anode is segmented from the hole transfer layer contact interface by introducing a mesh-shaped electrode structure. This segmentation separates the light transmission function (maintained by the mesh) from the electrical contact function (performed by the mesh wires), eliminating the continuous surface contact that causes defects while preserving light emission through the mesh openings.
2Illumination intensity
If a transparent anode (ITO) is used in OLED, then light emission is enabled, but light is absorbed by the anode reducing emission efficiency
Solution Approach 1:
The anode is transformed into a mesh-shaped structure with inherent porosity (openings between wires). This porous configuration allows light to pass through the anode with minimal absorption, as the light only interacts with the wire portions rather than a continuous opaque layer, thereby improving light emission efficiency.
3Ease of manufacture
If mesh shaped electrodes are formed by wet process, then manufacturing is simplified and cost reduced, but electrode material selection is constrained
Solution Approach 1:
An optical catalyst film is introduced as an intermediary layer between the substrate and the metal electrode. This catalyst film enables electroless plating of various metal materials (Ni, Au, Ag, Pt, Cu) by providing a surface for nucleation and growth. The catalyst film acts as a mediator that allows diverse metal materials to be deposited using the wet process, thus expanding material selection while maintaining manufacturing simplicity.
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
The mesh-shaped electrodes reduce surface defects, increase material selection latitude, and maintain brightness while simplifying the manufacturing process, enabling longer device lifespan and efficient light emission.
Implementation Method 1
forming an optical catalyst film by coating an optical catalyst material on a substrate; forming a water soluble polymer layer by coating a water soluble polymer compound on the optical catalyst film; producing a latent pattern of nuclei for growing crystals by selectively exposing the optical catalyst film and the water soluble polymer layer
Implementation Method 2
producing a metal pattern by plating the latent pattern of nuclei, and growing metal crystals
Data Source
AI summary
An organic light emitting device (OLED) and a white light emitting device are provided. The OLED includes a substrate, a mesh shaped anode formed on the substrate and designed to pass light, a cathode facing the anode, and an organic light emitting layer located between the anode and the cathode.