Tandem OLED Layer Inversion for Color Stability
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Solution Overview
Problem
Conventional tandem OLED display devices experience color shift over time due to varying emission colors caused by the same RGB electroluminescent layer sequence, leading to unstable irradiance.
Innovation Solution
A tandem electroluminescent device is designed with N electroluminescent units, where the first and Nth units have emitting layers with different physical quantities, and intermediate units have the same emitting layers in reverse order, ensuring stable emission colors regardless of driving current magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional white tandem OLED uses the same RGB electroluminescent layer sequence for each unit, then the device can be fabricated with simpler processes, but the emission color varies with driving current magnitude causing color shift over time
Solution Approach 1:
The patent inverts the sequence of electroluminescent layers in alternating tandem units. Specifically, odd-numbered units use the sequence R-G-B while even-numbered units use B-G-R. This inversion causes the color shifts in adjacent units to be opposite in direction, thereby compensating for each other and maintaining stable overall emission color across different driving current magnitudes.
2Duration of action of stationary object
If tandem OLED uses vertically stacked individual OLEDs to achieve full-color image, then luminous efficiency and operating life span are improved, but color shift over time occurs due to varying emission colors
Solution Approach 1:
The patent applies layer sequence inversion in alternating tandem units to counteract color shifts. By having odd units emit with a certain color deviation and even units emit with the opposite deviation, the overall emission color remains stable over time, preserving both the long operating life span and color accuracy of the display device.
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 maintains stable irradiance and improves color saturation by preventing color shifts, enhancing the efficiency and reliability of OLED display devices.
Implementation Method 1
An organic light-emitting diode (OLED) is a light-emitting diode employing an organic electroluminescent layer as an active layer
Data Source
AI summary
A system for displaying images is provided. The system includes a tandem electroluminescent device having a first electrode. N electroluminescent units are disposed on the first electrode in sequence, wherein N is an integral and not less than 2. A second electrode is disposed on the Nth electroluminescent unit. N−1 interconnecting electrodes are provided, wherein each of the interconnecting electrodes is disposed between two adjacent electroluminescent units. The first electroluminescent unit includes a first emitting layer and a second emitting layer in sequence from the first electrode, and the first and second emitting layer have different physical quantities. The Nth electroluminescent unit includes a third emitting layer and a fourth emitting layer in sequence from the first electrode. The physical quantity of the third emitting layer is the same as that of the second emitting layer. The physical quantity of the fourth emitting layer is the same as that of the first emitting layer.