Light Emitting Display Device with Differential Anode Thickness

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Solution Overview

Problem

Light emitting display devices face challenges in achieving high pure color and white efficiencies, particularly in red light, due to the reduction in luminance when maximizing external quantum efficiency for white light emission, which is advantageous for green or yellowish green light.

Innovation Solution

A light emitting display device configuration with a substrate having subpixels and anodes of varying thicknesses, incorporating a color conversion layer and filters to improve red, green, and blue light efficiencies, and a phosphorescent stack with a yellowish green and green emission layer, along with a red filter and blue filter to enhance color gamut and luminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a color conversion layer and color filter are used to improve white luminance and acquire red light efficiency, then red light exit efficiency is improved, but device structure becomes more complex

Engineering Contradiction:

Improvered light exit efficiencyVSAvoidstructure complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The color conversion layer is integrated directly into the red subpixel structure, merging the functions of light conversion and light emission within a single subpixel unit. This consolidation achieves improved red light exit efficiency without requiring separate complex optical paths or additional discrete components, thereby minimizing structural complexity while maintaining performance benefits

Inventive Principle:

Principle #5Merging (Combining)

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 improves pure color and white efficiencies by selectively converting and transmitting light through the use of differential anode thicknesses and color conversion layers, ensuring high luminance and color purity, particularly in red light emission.

Implementation Method 1

a color conversion layer and color filter provided under the first anode

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a phosphorescent stack including a red emission layer, a yellowish green emission layer and a green emission layer

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 3

a red filter and color conversion layer provided between the substrate and the first anode

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS20230217764A1Light emitting display device

Publication Date: 2023.07.06 LG DISPLAY CO LTD

AI summary

Disclosed is a light emitting display device including a substrate having first to fourth subpixels, first to fourth anodes provided respectively on the first to fourth subpixels, an emission unit provided on the first to fourth anodes, the emission unit including two or more blue stacks and a phosphorescent stack including at least a yellowish green emission layer and a green emission layer, a cathode provided on the emission unit, a red filter and a color conversion layer provided between the substrate and the first anode, a green filter provided between the substrate and the second anode, and a blue filter provided between the substrate and the third anode, wherein the first anode has a first thickness, and at least one of the second to fourth anodes has a second thickness greater than the thickness of the first anode.