Organic EL Light Extraction via Curved Reflective Electrode
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Solution Overview
Problem
The extraction efficiency of light in organic electroluminescent devices is low due to the reflection and absorption of light at the boundary surfaces, leading to increased power consumption and reduced device lifetime, with existing solutions either increasing costs or complexity in manufacturing.
Innovation Solution
An electroluminescence device with a stepped insulating layer having a tilted surface, where the first electrode extends to the stepped portion, forming a light reflecting surface that redirects parallel emitted light towards the second electrode, enhancing light extraction efficiency without increasing current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a current flowing to an organic EL device is increased to increase luminosity, then the luminosity is improved, but the power consumption is increased and the lifetime is reduced
Solution Approach 1:
The patent converts the harmful effect of light traveling parallel to the film surface (which was previously lost) into a beneficial effect by using a reflective electrode to redirect this light toward the extraction surface, thereby improving luminosity without increasing power consumption
Solution Approach 2:
The patent changes the directional distribution of emitted light by introducing a reflective electrode that redirects light from parallel propagation to upward propagation toward the extraction surface, effectively utilizing light in a different spatial dimension
2Productivity
If a transparent resin layer with cone shaped transparent resin is arranged to improve extraction efficiency, then the light extraction efficiency is improved, but the manufacturing cost is increased
Solution Approach 1:
The patent replaces expensive specialized optical adjustment films with a reflective electrode made of conventional reflective materials, achieving light extraction improvement through a more cost-effective approach
Solution Approach 2:
Instead of adding complex optical structures on the light extraction side, the patent inverts the approach by using the reflective electrode on the opposite side to redirect light, simplifying the overall structure
3Productivity
If a metal electrode with concave-convex surface is formed to improve extraction efficiency, then the light extraction efficiency is improved, but the manufacturing process becomes complex
Solution Approach 1:
The patent applies local quality by positioning the reflective electrode specifically at the boundary between the organic EL layer and the extraction surface, where it can most effectively redirect parallel-traveling light, rather than complicating the entire electrode structure
Solution Approach 2:
The patent employs a curved reflective surface on the reflective electrode that matches the curvature of the organic EL layer, enabling effective redirection of parallel-traveling light toward the extraction surface while maintaining 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 configuration increases the extraction efficiency of light from the organic electroluminescent layer, reducing power consumption and extending the device's lifetime by effectively utilizing previously lost light without complex manufacturing processes or increased costs.
Implementation Method 1
a first electrode including a light reflecting surface over the insulating layer
Data Source
AI summary
Light emitted within an organic EL device is effectively utilized, and a pixel is provided for improving the extraction efficiency of the light. Light extraction is efficiency is improved without increasing a current by effectively utilizing guided wave light which is a cause of the loss of light emitted by an organic EL device. In order to achieve this, a stepped portion is arrange in an insulating layer provided over a lower layer of a first electrode including a light reflecting surface, and a peripheral area of the first electrode is formed so as to contact the stepped portion. The reflecting surface is formed curved towards a second electrode side in the peripheral area of the first electrode from the stepped portion, light guided through the organic EL layer is reflected by the reflecting surface and emitted from the second electrode side.