OLED Pixel Sub-pixel Segmentation for High CRI and Wide Color Gamut

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Solution Overview

Problem

Conventional OLEDs face challenges in achieving high color rendering index (CRI) and wide color gamut simultaneously, particularly in display applications where both high CRI for illumination and wide color gamut for image rendering are required, often compromising on one aspect due to differing emission spectra needs.

Innovation Solution

The implementation of an OLED device with a plurality of sub-pixels, including red, green, blue, cyan, yellow, and orange sub-pixels, configured to achieve a minimum CRI of 85 and a minimum color gamut of 85% of a selected color space, such as DCI-3, BT.2020, or Adobe RGB 1998, using independently addressable stacks and color altering layers to optimize emission spectra.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional OLEDs use standard emission spectra for display applications, then color gamut is improved, but color rendering index deteriorates

Engineering Contradiction:

Improvecolor gamutVSAvoidcolor rendering index

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The pixel is divided into multiple sub-pixels (red, green, blue, cyan, yellow, orange) that can be independently controlled. This segmentation allows different sub-pixels to contribute to different aspects of color output, enabling simultaneous achievement of wide color gamut (through saturated RGB sub-pixels) and high CRI (through additional cyan, yellow, and orange sub-pixels that fill spectral gaps).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sub-pixels within the same pixel have different emission characteristics optimized for specific functions. The red, green, and blue sub-pixels provide saturated colors for wide gamut, while the cyan, yellow, and orange sub-pixels provide spectral components necessary for high color rendering. Each sub-pixel's emission spectrum is locally optimized for its specific role.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If OLEDs are configured for high CRI illumination, then color rendering index is improved, but color gamut deteriorates

Engineering Contradiction:

Improvecolor rendering indexVSAvoidcolor gamut

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The OLED device can dynamically adjust the emission intensity of each sub-pixel type based on the required function. For display applications, the saturated RGB sub-pixels are emphasized for wide gamut, while for illumination applications, the cyan, yellow, and orange sub-pixels are activated to improve color rendering. This dynamic control allows the same device to optimize for different performance criteria as needed.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If conventional OLEDs use white backlight with absorption filters, then color gamut is improved, but device complexity increases

Engineering Contradiction:

Improvecolor gamutVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for white backlight and absorption filters by using directly emissive organic materials in the OLED structure. Instead of generating white light and then filtering it to obtain colored light, the OLED emits colored light directly through electroluminescence of organic compounds, simplifying the device architecture while maintaining or improving color gamut.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical/optical filtering system (white backlight + absorption filters) is replaced with an electro-optical emission system. The OLED uses electrical excitation of organic materials to produce colored light directly, substituting the complex filtering mechanism with a more efficient and simpler electroluminescent emission process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables the OLED device to simultaneously achieve high CRI for illumination and wide color gamut for image rendering, surpassing industry standards by rendering greater than 85% of an industry standard wide color gamut, while maintaining efficient and effective light emission.

Implementation Method 1

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

One application for phosphorescent molecules capable of phosphorescent emission is a full color display

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS20230363226A1Organic electroluminescent devices

Publication Date: 2023.11.09 UNIVERSAL DISPLAY CORP

AI summary

Embodiments of the disclosed subject matter provide a device that may include an emissive surface having a plurality of pixels, where each pixel has four or more sub-pixels, and where each pixel may be capable of: (a) a color rendering index (CRI) that is ga minimum of 85; and (b) a minimum color gamut equal to 85% of a color space, wherein the color space is selected from at least one of a group consisting of: DCI-3, BT.2020, and Adobe™ RGB 1998.