OLED Display with Tandem White and Blue Diodes
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Solution Overview
Problem
Organic light-emitting diode displays with white diodes face challenges in achieving a desired color gamut, particularly in reproducing blue image content, due to low efficiency of blue emissive material, leading to increased current requirements and reduced display lifetime.
Innovation Solution
An organic light-emitting diode display configuration featuring sets of red, green, and white pixels with unfiltered white and blue diodes, where white diodes are tandem diodes with multiple emissive layers, and blue diodes have a common blue emissive layer and an additional blue emissive layer, allowing for efficient white and blue light emission without color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrowband color filter elements are used to enhance color gamut, then color reproduction is improved, but power efficiency deteriorates
Solution Approach 1:
The invention extracts and eliminates the color filter layer from the display structure. Instead of using color filters to generate colored pixels, the display uses white emissive diodes that directly emit white light, and blue emissive diodes that directly emit blue light, removing the need for color filtering and thereby improving power efficiency while maintaining color gamut
Solution Approach 2:
The invention changes the emission parameters of the diodes by using tandem diode structures with multiple emissive layers. The white diodes contain blue, yellow, and red emissive layers that work together to produce white light, while blue diodes use enhanced blue emissive layers, allowing direct emission of the desired colors without filtering
2Illumination intensity
If white diodes are driven with large currents to compensate for low blue emissive material efficiency, then blue pixel brightness is improved, but display lifetime deteriorates
Solution Approach 1:
The invention uses composite tandem diode structures where multiple emissive materials are combined in series. The white diode contains blue, yellow, and red emissive layers, and the blue diode contains enhanced blue emissive layers. This composite structure improves the overall efficiency of blue light generation, allowing adequate brightness at lower current levels and thereby extending display lifetime
Solution Approach 2:
The invention adds a vertical dimension to light generation by stacking multiple emissive layers in the tandem diode structure. Instead of relying on a single emissive layer, the stacked layers work together to produce the desired white or blue light output, improving efficiency and reducing the need for high current operation
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 color gamut and reduces power consumption, thereby extending the lifetime of the display by optimizing the emission of white and blue light without the need for color filters.
Implementation Method 1
Organic light-emitting diode display
Data Source
AI summary
An organic light-emitting diode display may have an array of pixels with sets of pixels arranged in rows and columns. Each set of pixels includes a red pixel, a green pixel, a blue pixel, and a white pixel. The red pixels each have a white diode and a red color filter element to impart a red color to white light from that white diode. The green pixels each have a white diode and a green color filter element to impart a green color to white light from that white diode. The white pixels each have an unfiltered white diode. The blue pixels each have an unfiltered blue diode. The unfiltered white and blue diodes do not have color filters and emit white and blue light for the white and blue pixels, respectively. The white and blue diodes may be tandem diodes having two or more emissive layers.