Porous Glass Substrate for OLED Light Extraction
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Solution Overview
Problem
Current OLEDs suffer from low light extraction efficiency due to refractive index differences between the glass substrate and the anode, leading to significant light loss through waveguiding and total internal reflection, and existing solutions like silica aerogel coatings are complex and costly to manufacture, while concave-convex structures can cause leakage currents and color shift.
Innovation Solution
A porous glass substrate with a porous layer having a refractive index lower than the glass substrate, featuring a concave-convex pattern, is used to increase light extraction efficiency by redirecting trapped light and reducing waveguiding, while avoiding the complexities of silica aerogel coatings and minimizing the risk of leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar glass substrate is used, then the manufacturing process is simple, but light extraction efficiency is low due to waveguiding and total internal reflection
Solution Approach 1:
The patent applies a porous layer formed on the glass substrate surface through chemical etching. This porous structure creates refractive index variations that disrupt waveguiding modes and reduce total internal reflection, thereby improving light extraction efficiency while maintaining compatibility with standard glass substrate manufacturing processes
Solution Approach 2:
The chemical etching process creates curved, porous surface features rather than sharp geometric structures. These curved porous features effectively scatter light and disrupt waveguiding without creating sharp edges that could cause electrical leakage, resolving the contradiction between improving light extraction and maintaining manufacturing simplicity
2Loss of energy
If silica aerogel coating is applied to improve light extraction, then light extraction efficiency increases, but manufacturing complexity and cost increase significantly
Solution Approach 1:
Instead of applying a separate silica aerogel coating layer, the patent extracts material from the glass substrate itself through chemical etching to form the porous light extraction layer. This eliminates the need for additional coating materials and complex multi-layer deposition processes, significantly simplifying manufacturing while achieving the desired light extraction improvement
Solution Approach 2:
The patent combines the substrate and light extraction layer into a single integrated structure. The porous layer is formed directly on the glass substrate through in-situ chemical etching, merging what would traditionally be separate components (substrate + aerogel coating) into one unified structure, thereby reducing manufacturing complexity and cost
3Loss of energy
If concave-convex structure is formed below anode to extract light, then light extraction efficiency improves, but leakage current increases due to sharp protruding portions
Solution Approach 1:
The patent uses a porous layer with controlled pore sizes and distributions instead of macroscopic concave-convex structures. The porous structure provides gradual refractive index transitions that improve light extraction while maintaining surface smoothness at the scale relevant to electrical conduction, preventing current concentration and leakage
Solution Approach 2:
The chemical etching process creates localized porous regions with specific pore sizes and densities optimized for light extraction. The porous structure provides the necessary surface complexity for light scattering while maintaining overall surface flatness and avoiding sharp protrusions that would cause electrical leakage, achieving local optimization of both optical and electrical properties
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 porous glass substrate enhances light extraction efficiency, reduces power consumption, and minimizes heat generation, leading to increased OLED lifespan with improved color mixing and reduced color shift, and simplifies the manufacturing process.
Implementation Method 1
about 35%, and thus only about 20% of the generated light is emitted to the outside. When the light is directed outward from the inside of the glass substrate 10, a ray of the light having an angle of incidence greater than a critical angle is totally reflected and is trapped inside the glass substrate 10
Implementation Method 2
the refractive index of the porous layer being smaller than the refractive index of the glass substrate
Data Source
AI summary
A porous glass substrate for displays and a method of manufacturing the same, with which the optical characteristics of a display such as an organic light-emitting device (OLED) can be improved. The porous glass substrate includes a glass substrate and a porous layer formed in at least one portion of one surface of the glass substrate and extending into the glass substrate, the refractive index of the porous layer being smaller than the refractive index of the glass substrate. The porous layer has a plurality of pores which is formed in the glass substrate such that at least one component of the glass substrate except for silicon dioxide (SiO2) is eluted from the glass substrate.