Tandem White OLED with Three Light-Emitting Units
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Solution Overview
Problem
Current OLED devices face challenges in achieving efficient broadband emission with stable luminance and high color temperature, particularly in producing white light with significant red, green, and blue components, while maintaining low power consumption and extended lifetime.
Innovation Solution
The implementation of a tandem OLED structure with three light-emitting units, where the first unit emits light with multiple peaks above 500 nm and the second and third units emit light with substantial peaks below 500 nm, interconnected by intermediate connectors, to achieve a color temperature greater than 7000K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light-emitting layer is used to achieve broadband emission, then manufacturing complexity is reduced, but manufacturing precision becomes difficult to control due to the need for careful dopant concentration control
Solution Approach 1:
The device is divided into multiple light-emitting layers (first, second, and third light-emitting layers) instead of using a single layer. Each layer can be independently optimized for specific wavelength ranges, eliminating the need for precise dopant concentration control in a single layer while achieving broadband emission across the visible spectrum.
2Reliability
If two light-emitting layers are used to improve color and luminance efficiency, then color quality and stability are enhanced, but achieving strong emission intensity across red, green, and blue portions becomes difficult
Solution Approach 1:
The emission spectrum is segmented across three light-emitting layers, with each layer targeting specific wavelength ranges. This segmentation allows each layer to be optimized for strong emission in its designated range, collectively achieving intense and balanced emission across the entire visible spectrum including red, green, and blue portions.
Solution Approach 2:
The solution transitions from a single-layer or two-layer structure to a three-layer vertical stack, adding a dimensional aspect to the emission spectrum coverage. This vertical stacking in the structural dimension enables comprehensive spectral coverage that cannot be achieved with fewer layers, achieving both high intensity and broad spectrum emission.
3Reliability
If a tandem OLED structure with multiple light-emitting units is used to increase luminance efficiency and lifetime, then efficiency and stability are improved, but driving voltage increases in proportion to the number of stacked units
Solution Approach 1:
The tandem structure is segmented into three distinct light-emitting units stacked vertically, with each unit contributing to broadband emission. This segmentation allows independent optimization of each unit's emission characteristics while sharing common electrodes and intermediate connectors, achieving enhanced lifetime and efficiency without excessive voltage increase compared to fewer-layer designs.
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 enhances the color temperature, efficiency, and luminance stability of OLED displays, suitable for large displays like televisions, with improved blue emission and reduced blue pixel lifetime degradation.
Implementation Method 1
An organic light-emitting diode device, also called an OLED, commonly includes an anode, a cathode, and an organic electroluminescent (EL) unit sandwiched between the anode and the cathode
Data Source
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AI summary
An OLED device having two spaced electrodes including: first, second, and third light-emitting units disposed between the electrodes, the first light-emitting unit produces light that has multiple peaks at wavelengths longer than 500 nm and substantially no emission at wavelengths shorter than 480 nm, and the second and third light-emitting units produce light that has substantial emission at wavelengths shorter than 500 nm; intermediate connectors respectively disposed between the first and second light-emitting units, and between the second and third light-emitting units; and wherein the OLED device emits light with a color temperature greater than 7,000K.