Display Device With Tailored Hole-Transport Layers for Wide Viewing Angles
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Solution Overview
Problem
Current display devices face challenges in maintaining high visibility and color accuracy when viewed from oblique angles, leading to reduced effectiveness in applications requiring wide viewing angles and accurate color representation.
Innovation Solution
A display device comprising multiple light-emitting elements with specific peak wavelengths and structural configurations, including reflective and transflective electrodes, and shared hole-injection and electron-transport layers, to minimize chromaticity differences and luminance variations across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional light-emitting elements with uniform structure are used, then manufacturing is simple, but viewing angle is narrow and color accuracy degrades at oblique angles
Solution Approach 1:
The patent applies local quality by making each light-emitting element have a tailored structure: the first element (blue) has a thicker hole-transport layer, the second element (red) has a standard structure, and the third element (green) has a thinner hole-transport layer. This localized structural differentiation optimizes optical extraction and color purity for each wavelength while maintaining overall device functionality and achieving wide viewing angles without excessive complexity.
Solution Approach 2:
The patent changes physical parameters of the light-emitting elements, specifically the thickness of the hole-transport layer and the distance between electrodes, to optimize performance. The first element has a hole-transport layer thickness of 50-150 nm, the second has 20-80 nm, and the third has 30-100 nm. These parameter variations enable wide viewing angles and accurate color representation across different viewing conditions.
2Adaptability or versatility
If light-emitting elements with different thicknesses are used to achieve wide viewing angle, then viewing angle improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for the hole-transport layer thickness (50-150 nm for first element, 20-80 nm for second, 30-100 nm for third) and electrode distances, providing manufacturing guidelines that balance performance optimization with manufacturability. These ranges enable wide viewing angles while maintaining reasonable manufacturing precision requirements through standardized process controls.
3Illumination intensity
If standard light-emitting elements are used, then device complexity is low, but color gamut is narrow and visibility at oblique angles is poor
Solution Approach 1:
The patent implements local quality by configuring each light-emitting element with specific structural characteristics: the first element uses a thicker hole-transport layer (50-150 nm) for blue light optimization, the second uses a standard structure for red light, and the third uses a thinner hole-transport layer (30-100 nm) for green light. This localized optimization achieves wide color gamut and high visibility at oblique angles while maintaining reasonable device complexity.
Solution Approach 2:
The patent employs composite material structures within each light-emitting element, combining organic light-emitting layers with inorganic electrode materials (reflective and transflective electrodes). The composite structure of different thicknesses and materials optimizes light extraction efficiency and color purity, achieving wide color gamut and excellent visibility without excessive device complexity.
4Measurement precision
If light-emitting elements with optimized thickness are used, then color accuracy improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes color accuracy by controlling the hole-transport layer thickness within specific ranges (50-150 nm for blue, 20-80 nm for red, 30-100 nm for green) and electrode distances. These parameter specifications provide clear manufacturing targets that balance color accuracy requirements with manufacturing cost, avoiding excessive precision requirements while achieving wide color gamut and accurate color representation.
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 a wide viewing angle and wide color gamut, ensuring consistent image quality and high visibility from various angles, suitable for flexible and large-screen applications.
Implementation Method 1
Light-emitting elements utilizing electroluminescence (hereinafter referred to as EL elements)
Implementation Method 2
One of the pair of electrodes includes a reflective electrode
Data Source
AI summary
A display device with a wide viewing angle is provided. A display device capable of displaying an image with a wide color gamut is provided. A display device includes a first light-emitting element, a second light-emitting element, and a third light-emitting element. The light-emitting elements each include a pair of electrodes and a light-emitting layer. One of the pair of electrodes includes a reflective electrode, and the other of the pair of electrodes includes a transflective electrode. The light-emitting layers of the light-emitting elements are different from each other. A first peak wavelength of the emission spectrum of the first light-emitting element is greater than or equal to 400 nm and less than or equal to 480 nm. A second peak wavelength of the emission spectrum of the second light-emitting element is greater than or equal to 580 nm and less than or equal to 700 nm. A third peak wavelength of the emission spectrum of the third light-emitting element is between the first peak wavelength and the second peak wavelength. The distance between the pair of electrodes of the first light-emitting element is longest and that of the second light-emitting element is second longest.