Tandem OLED Subpixel Charge-Generation Layer Crosstalk
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Solution Overview
Problem
Display devices face issues with color shift between low and high luminance settings and increased resolution leading to crosstalk due to current flow between subpixels, affecting display quality and reliability.
Innovation Solution
A display device with a tandem structure of light-emitting units and charge-generation layers, where each subpixel includes a light-emitting device and a coloring layer, with a common electrode and insulating layers to prevent leakage current and maintain high aperture ratio, allowing for precise control of emission spectra and reduced crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resolution of display device is increased, then display quality is improved, but crosstalk occurs due to current flow between subpixels
Solution Approach 1:
A charge-generation layer is introduced as an intermediary component between light-emitting units. This layer generates charges that suppress leakage current flow between adjacent subpixels, thereby preventing crosstalk while maintaining high resolution display quality
Solution Approach 2:
The harmful leakage current is extracted and suppressed by introducing the charge-generation layer that generates opposite charges to neutralize and block the unwanted current flow between subpixels
2Illumination intensity
If luminance is increased, then display brightness is improved, but color shift occurs between low and high luminance settings
Solution Approach 1:
The emission spectrum characteristics are controlled by adjusting the composition ratio of first and second light-emitting materials in the EL layer. By optimizing this parameter, the device achieves consistent color output across different luminance levels while maintaining high brightness capability
3Productivity
If aperture ratio is increased, then light emission efficiency is improved, but structural complexity increases due to additional layers
Solution Approach 1:
The charge-generation layer serves multiple functions simultaneously: it generates charges to suppress leakage current, maintains color consistency across luminance levels, and preserves high aperture ratio. This multi-functionality reduces the need for additional separate components, managing 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
The solution provides a display device with minimal color difference between low and high luminance settings, achieving high resolution, high definition, and high reliability by preventing crosstalk and ensuring consistent emission spectra across luminance levels.
Implementation Method 1
Light-emitting devices (also referred to as EL devices or EL elements) utilizing electroluminescence (hereinafter referred to as EL)
Implementation Method 2
a first coloring layer transmitting blue light
Data Source
AI summary
A display device with high display quality is provided. The display device includes a first subpixel including a first light-emitting device and a first coloring layer transmitting blue light in a display portion. The first light-emitting device includes a first pixel electrode, a first EL layer, and a common electrode. The first EL layer includes a first light-emitting material emitting blue light and a second light-emitting material emitting light with a longer wavelength than blue light. The first EL layer includes a first light-emitting unit over the first pixel electrode, a charge-generation layer over the first light-emitting unit, and a second light-emitting unit over the charge-generation layer. In an emission spectrum of blue display by the display portion at a low luminance, the intensity of a first emission peak at a wavelength longer than or equal to 400 nm and shorter than 500 nm is assumed to be 1; in this case, the intensity of a second emission peak at a wavelength longer than or equal to 500 nm and shorter than or equal to 700 nm in the emission spectrum is lower than or equal to 0.5.