Composite Electrode Light Extraction via Scattering Layer Integration
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Solution Overview
Problem
Existing OLED devices suffer from significant light loss due to internal reflection, with only 20% of generated light being emitted effectively, and current light-scattering techniques struggle with power distribution and manufacturability issues.
Innovation Solution
A multi-layer composite electrode structure comprising a transparent conductive layer, a reflective conductive layer, and light-scattering layers between them, where the scattering layers are less conductive than the reflective layer, allowing for improved light extraction and power distribution without requiring complex patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a light-scattering layer is added to improve light extraction, then light emission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the light-scattering layer with the cathode layer into a single integrated structure. The cathode serves dual functions: as an electrical electrode and as a light-scattering layer. This merging eliminates the need for a separate light-scattering layer, thereby improving light extraction efficiency while avoiding increased device complexity.
Solution Approach 2:
The cathode layer is designed to perform multiple functions simultaneously: electrical conduction and light scattering. By making the cathode multi-functional, the patent avoids adding extra layers for light scattering, thus improving light emission efficiency without increasing device complexity.
2Productivity
If a light-scattering layer is added to improve light extraction, then light emission efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the light-scattering function with the cathode layer, eliminating the need for separate deposition processes for a dedicated light-scattering layer. This reduces manufacturing steps and complexity while achieving improved light extraction efficiency.
Solution Approach 2:
The cathode layer is designed to serve multiple purposes including light scattering, which means it can be deposited using standard cathode deposition processes without requiring additional manufacturing steps for light scattering functionality.
3Power
If the light-scattering layer is made highly conductive, then power distribution is improved, but light scattering performance deteriorates
Solution Approach 1:
The patent applies local quality by creating regions of different conductivity within the cathode layer. Highly conductive regions provide power distribution, while regions with lower conductivity or higher scattering centers provide light scattering functionality. This spatial variation in properties allows both functions to coexist optimally.
Solution Approach 2:
The patent changes physical parameters of the cathode layer, such as material composition, thickness, and morphology, to achieve optimal balance between conductivity and light scattering. By adjusting these parameters, the cathode can simultaneously provide adequate power distribution and effective light scattering.
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
Enhances light-emission efficiency and manufacturability by effectively redirecting trapped light and improving current distribution within the OLED device, leading to increased light output and reduced manufacturing complexities.
Implementation Method 1
A multi-layer composite electrode structure comprising a transparent conductive layer, a reflective conductive layer, and light-scattering layers between them, where the scattering layers are less conductive than the reflective layer, allowing for improved light extraction
Implementation Method 2
A multi-layer composite electrode structure comprising a transparent conductive layer, a reflective conductive layer
Data Source
Figure 1~4
Figure 5~7
AI summary
A multi-layer composite electrode (16) for a light-emitting device, comprising: a transparent, conductive layer (15); a reflective, conductive layer (17) in electrical contact with the transparent, conductive layer; and a light-scattering layer (22) formed between the transparent, conductive layer and the reflective, conductive layer over only a first portion (60) of the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is in electrical contact with the transparent, conductive layer over a second portion (62) of the transparent, conductive layer where the light-scattering layer is not formed. Also disclosed is a method of making such a multi-layer composite electrode in a light emitting device, and an organic light-emitting diode (OLED) device comprising such a composite electrode.