Organic Electroluminescence Element Anode Structure
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Solution Overview
Problem
Existing organic electroluminescence elements face issues with luminance unevenness and low external quantum efficiency due to the higher sheet resistance of anodes made from transparent conducting oxides compared to cathodes, leading to potential luminance inhomogeneity and reduced efficiency.
Innovation Solution
The organic electroluminescence element incorporates a second electrode with openings to expose the light-emitting layer, an electrically conductive layer for light transmission, and an insulating layer to overlap the electrode, reducing resistivity and enhancing light emission, while the second electrode is made of a metal powder and organic binder mixture to decrease resistance further.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an anode made of transparent conducting oxide (ITO or IZO) is used, then the electrode can be light transmissive, but the sheet resistance is larger than that of metal cathodes, leading to larger potential gradient and in-plane luminance unevenness
Solution Approach 1:
The anode is divided into a transparent conducting oxide layer and a separate metal fine-line pattern layer. This segmentation allows the TCO layer to provide light transmissivity while the metal pattern layer provides low resistance pathways to reduce potential gradients and improve luminance uniformity.
Solution Approach 2:
The anode is constructed as a composite structure combining transparent conducting oxide material and metal material. This composite approach leverages the optical properties of TCO (transparency) and the electrical properties of metal (low resistance) to simultaneously achieve light transmissivity and luminance uniformity.
2Manufacturing precision
If a metal fine-line pattern layer is added to the anode, then sheet resistance is reduced and luminance uniformity improves, but the device complexity increases
Solution Approach 1:
The metal fine-line pattern layer serves multiple functions: it acts as an additional electrode layer for electrical conduction, provides a scaffold for subsequent functional layers, and enables both low resistance and optical transparency when combined with the TCO layer. This multi-functionality justifies the added structural complexity.
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 reduces luminance unevenness and improves external quantum efficiency by ensuring even voltage application and efficient light transmission, resulting in enhanced luminous performance.
Implementation Method 1
a light-emitting layer (32) which emits light when a predetermined voltage is applied between the first electrode layer (20) and the second electrode layer (40)
Implementation Method 2
The electrically conductive layer (50) is configured to allow the light to pass therethrough
Data Source
AI summary
The organic electroluminescence element in accordance with the present invention includes: a light-emitting layer; a first electrode layer on a first surface in a thickness direction of the light-emitting layer; a second electrode layer on a second surface in the thickness direction of the light-emitting layer; an electrically conductive layer; and an insulating layer. The light-emitting layer is configured to emit light when a predetermined voltage is applied between the first and second electrode layers. The second electrode layer includes an electrode part covering the second surface and an opening part formed in the electrode part to expose the second surface. The electrically conductive layer is designed to allow the light to pass therethrough, and is interposed between the second surface and the second electrode layer to cover the second surface. The insulating layer is interposed between the second surface and the electrically conductive layer to overlap the electrode part.