Reflective Pixel Definition Structure for OLED Light Leakage
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Solution Overview
Problem
Conventional active matrix organic electroluminescent devices suffer from light leakage and luminescence interference due to side emission from one light emitting diode interfering with adjacent diodes, leading to reduced luminance efficiency, especially with the use of opaque organic compounds for pixel definition layers which have inferior electrical and optical characteristics.
Innovation Solution
The implementation of a reflective pixel definition structure with spaced pixel definition layers separated by a trench, where the sidewalls and bottom of the trench are covered by a reflective layer, allowing side emission to be transmitted out without interfering with adjacent pixel areas, and using the same material and process for the reflective layer and second electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent compounds are used as pixel definition layers, then light transmission is maintained, but side emission light reflects off the cathode and causes light leakage and luminescence interference
Solution Approach 1:
A reflective layer is introduced as an intermediary between the pixel definition layer and the cathode. This reflective layer redirects side emission light away from adjacent pixels, preventing light leakage and luminescence interference while allowing the pixel definition layer to remain transparent for light transmission.
2Object-affected harmful factors
If opaque organic compounds are used as pixel definition layers, then light leakage and luminescence interference are reduced, but luminance efficiency is reduced due to absorption of side emission
Solution Approach 1:
The reflective layer serves as a mediator that redirects side emission light instead of absorbing it. This allows the pixel definition layer to be transparent, maintaining light transmission, while the reflective layer prevents light leakage by redirecting side emission away from adjacent pixels without absorbing the light energy.
3Object-affected harmful factors
If opaque organic compounds with carbon-containing material are used for pixel definition layers, then light leakage is reduced, but electrical and optical characteristics deteriorate
Solution Approach 1:
The reflective layer is introduced as an intermediary that handles light reflection, allowing the pixel definition layer to use transparent compounds with superior electrical and optical characteristics. The reflective layer prevents light leakage without requiring the pixel definition layer to be made of opaque carbon-containing materials.
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 approach effectively prevents light leakage and luminescence interference, significantly increasing extraction efficiency and maintaining high color purity without increasing process complexity.
Implementation Method 1
a reflective layer formed on the surface of the pixel definition layers. Particularly, the pixel definition layers are separated by a trench, sidewalls and bottom of which are covered by the reflective layer. Since side emission can be transmitted out without interfering with the adjacent pixel areas, light leakage and luminescence interference are avoided
Implementation Method 2
Each of light emitting diodes R, G, and B comprises an ITO electrode serving as an anode 30, electroluminescent layers 40, and a metal electrode serving as a cathode 50
Data Source
AI summary
Systems for displaying images and fabrication method thereof are provided. A representative system incorporates an active matrix organic electroluminescent device that includes pixel areas, a pair of spaced pixel definition layers surrounding each pixel area, and a reflective layer formed on the surface of the pixel definition layers. Particularly, the pair of spaced pixel definition layers is separated by a trench, and the reflective layer covers the sidewalls and bottom of the trench.