OLED Phase Delay Capping Layer for External Light Reflection Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light emitting diode (OLED) displays face issues with external light reflection, which deteriorate black color expression and contrast, especially in bright environments, leading to reduced visibility.
Innovation Solution
The implementation of a phase delay capping layer with a refractive index between 1.8 and 2.7, formed through thermal deposition at an inclined angle, which converts linearly polarized external light to circularly polarized light and back to linearly polarized light, is used in conjunction with a polarizing plate to minimize external light reflection. This layer is made of materials like titanium oxide or zinc oxide and has a thickness of 0.9 to 1.3 μm, enhancing light use efficiency and protecting the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional OLED display structure is used, then the device is simple and thin, but external light reflection deteriorates black color expression and contrast
Solution Approach 1:
A phase delay capping layer with specific refractive index (1.8-2.7) is introduced as an intermediary component between the OLED and the external environment. This layer converts linearly polarized external light into circularly polarized light, which then reflects off the reflective surface and converts back to linearly polarized light that is blocked by the polarizing plate, effectively suppressing external light reflection without requiring complex multi-layer structures
Solution Approach 2:
The phase delay capping layer utilizes specific material parameters (refractive index between 1.8 and 2.7, thickness of 0.9-1.3 μm) to achieve the desired optical effect. By carefully controlling these parameters, the layer creates a quarter-wave plate effect that transforms the polarization state of external light, enabling reflection suppression while maintaining device simplicity
2Object-affected harmful factors
If a phase delay capping layer is added to suppress external light reflection, then visibility and contrast improve, but the device thickness increases
Solution Approach 1:
The phase delay capping layer is designed with an optimized thickness range of 0.9-1.3 μm, which is sufficient to achieve the quarter-wave plate effect for external light wavelength ranges (380-780 nm). This thin thickness minimizes the increase in overall device thickness while still providing effective external light reflection suppression and improving visibility by approximately 50%
3Object-affected harmful factors
If the phase delay capping layer is made thicker to improve reflection suppression, then external light reflection decreases, but the device thickness and complexity increase
Solution Approach 1:
The phase delay capping layer is designed with an optimized thickness range of 0.9-1.3 μm, which is sufficient to achieve the quarter-wave plate effect for external light wavelength ranges (380-780 nm). This thin thickness minimizes the increase in overall device thickness while still providing effective external light reflection suppression and improving visibility by approximately 50%
Solution Approach 2:
The phase delay capping layer incorporates cylindrical microelements with specific orientation (inclined at 40-50 degrees with respect to deposition direction) to create localized optical anisotropy. This local structural quality enables the layer to function as a quarter-wave plate with optimized thickness, achieving effective external light reflection suppression without requiring excessive thickness
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 solution effectively suppresses external light reflection, improving the OLED display's visibility and contrast by approximately 50% by ensuring that reflected light is absorbed rather than passed through, thus maintaining better image quality in bright environments.
Implementation Method 1
a phase delay capping layer formed over the organic light emitting diode, configured to input linearly polarized light and output circularly polarized light
Implementation Method 2
a polarizing plate formed over the second substrate, configured to pass through only linearly polarized light
Implementation Method 3
the organic light emitting diode including a reflective surface configured to reflect light incident to the organic light emitting diode
Implementation Method 4
The phase delay capping layer may be formed through a thermal deposition process
Implementation Method 5
The phase delay capping layer may include an oblique deposition layer. The thermal deposition process may be performed with the substrate main body inclined at an angle of between about 40 degrees to about 50 degrees with respect to a deposition direction
Data Source
AI summary
An OLED display and a manufacturing method thereof are disclosed. The OLED display includes: a first substrate, an organic light emitting diode formed over the first substrate, the organic light emitting diode including a reflective surface configured to reflect light incident to the organic light emitting diode, a phase delay capping layer formed over the organic light emitting diode, configured to input linearly polarized light and output circularly polarized light, a second substrate disposed over the phase delay capping layer, and a polarizing plate formed over the second substrate, configured to pass through only linearly polarized light.