OLED Resonance Structure with Asymmetric Buffer Patterns
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Solution Overview
Problem
Organic light-emitting display devices suffer from reduced light extraction efficiency and color purity due to wide emission wavelengths and internal reflection of photons, leading to a color shift when viewed from different angles, which existing solutions like distributed Bragg reflectors and resonance structures cannot fully mitigate.
Innovation Solution
The use of a resonance structure with an uneven pattern unit formed by patterning the buffer layer, first insulating layer, and active layer, combined with a semi-transmissive second pixel electrode and a reflective opposite electrode, to enhance light extraction efficiency and reduce color shift by creating a resonant mirror effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a resonance structure is used to increase light extraction efficiency, then light efficiency is improved, but color shift dependent on viewing angle is caused
Solution Approach 1:
The patent introduces an uneven pattern unit with asymmetric geometric shapes (triangles, trapezoids, or combinations) into the resonance structure. This asymmetry modifies the resonant characteristics to broaden the emission wavelength distribution, thereby reducing the viewing angle-dependent color shift while maintaining enhanced light extraction efficiency. The asymmetric pattern creates multiple scattering paths that distribute light more uniformly across different viewing angles.
Solution Approach 2:
The uneven pattern unit is selectively applied in specific regions of the resonance structure rather than uniformly throughout. This local modification allows the patent to maintain the resonant enhancement effect in certain areas while introducing wavelength-broadening characteristics in specific zones, achieving a balance between light extraction efficiency and color consistency across viewing angles.
2Area of stationary object
If organic light-emitting layer emits light in arbitrary directions, then light coverage is improved, but internal reflection increases and light extraction efficiency decreases
Solution Approach 1:
The patent introduces a vertical dimension to light extraction by creating an uneven pattern unit with varying heights and depths. This three-dimensional structure adds a new dimension for light scattering and extraction, allowing photons that would otherwise be trapped by internal reflection to escape through the uneven interfaces at different vertical levels, thereby improving light extraction efficiency without compromising wide-area coverage.
Solution Approach 2:
The uneven pattern unit acts as an intermediary structure between the organic light-emitting layer and the external environment. It provides multiple intermediate interfaces with different refractive indices and geometries that facilitate gradual light extraction, reducing total internal reflection effects while maintaining broad light distribution across the display area.
3Loss of energy
If distributed Bragg reflector mirror is used to increase light extraction efficiency, then light efficiency is improved, but device complexity increases
Solution Approach 1:
The patent modifies the geometric parameters of existing structure layers (buffer layer, insulating layers, electrode layers) by introducing uneven patterns with varying heights, widths, and shapes. This approach achieves enhanced light extraction efficiency by changing the optical parameters (scattering, reflection, refraction) of existing layers rather than adding entirely new components, thereby improving performance while minimizing increases in device complexity.
Solution Approach 2:
The uneven pattern unit serves multiple functions simultaneously: it acts as a resonance structure for light extraction enhancement, a wavelength-broadening element for color consistency, and a scattering center for reducing internal reflection. By making existing structure layers multi-functional through geometric modification, the patent avoids adding separate components that would increase device 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
This approach increases light extraction efficiency and color reproduction quality while minimizing color shift when viewed from different angles, improving the overall performance of organic light-emitting display devices.
Implementation Method 1
The present invention provides an organic light-emitting display device, which may reduce a color shift according that is dependent upon a viewing angle by using a resonance structure including an uneven portion
Implementation Method 2
The opposite electrode may be a reflective electrode
Implementation Method 3
combined with a semi-transmissive second pixel electrode and a reflective opposite electrode, to enhance light extraction efficiency and reduce color shift by creating a resonant mirror effect
Data Source
AI summary
An organic light-emitting display device includes a substrate. A buffer layer is formed on the substrate. A thin film transistor is disposed on the buffer layer. The thin film transistor includes an active layer, a gate electrode, a source electrode, a drain electrode, a first insulating layer, and a second insulating layer. An uneven pattern is formed by patterning the buffer layer. A first pixel electrode is disposed in an opening formed in the second insulating layer. The first pixel electrode includes a transparent conductive oxide. A second pixel electrode is disposed on the first pixel electrode. The second pixel electrode includes a semi-transmissive layer. An organic lighting-emitting layer is formed on the second pixel electrode. An opposite electrode is formed on the organic lighting-emitting layer.