OLED Protrusion Structure for Light Extraction Efficiency
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Solution Overview
Problem
In organic light emitting devices (OLEDs), the refractive index difference between different structures leads to significant light total reflection at boundaries, reducing output efficiency as most light cannot emerge through the package substrate.
Innovation Solution
A protrusion formed of a first transparent material on the package substrate with a surface covered by a second transparent material of higher refractive index, altering the optical path of incident light to reduce total reflection and enhance light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional package substrate structure is used, then the device structure is simple, but light total reflection occurs at boundaries reducing output efficiency
Solution Approach 1:
The patent introduces a protrusion structure that extends vertically from the package substrate surface, adding a dimensional element to alter light propagation paths. This protrusion creates multiple interfaces and angles for light interaction, enabling light that would normally undergo total internal reflection to escape through the protrusion's geometric configuration, thereby improving light extraction efficiency without fundamentally complicating the manufacturing process
Solution Approach 2:
The protrusion acts as an intermediary structure between the high-refractive-index OLED layers and the lower-refractive-index external environment. By introducing this intermediate geometric feature, the patent provides a transition pathway that facilitates light extraction, mediating the optical impedance mismatch between the OLED stack and air, thus reducing total internal reflection losses
2Device complexity
If the package substrate material is used directly, then the manufacturing process is simple, but significant light total reflection reduces effective display area
Solution Approach 1:
The protrusion structure introduces curved or angled surfaces that deviate from the flat package substrate geometry. These non-planar surfaces alter the incident angles of light rays, enabling them to satisfy escape cone conditions and extract from the OLED structure. The curved geometry effectively increases the light extraction surface area, thereby expanding the effective display area without substantially increasing 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
The solution improves light output efficiency by allowing more light to emerge through the package substrate, reducing total reflection at the boundary and increasing the effective display area.
Implementation Method 1
the refractive index of the second transparent material is larger than the refractive index of the first transparent material
Implementation Method 2
the refractive index difference between different structures leads to significant light total reflection at boundaries
Data Source
AI summary
An organic light emitting device and a display apparatus are disclosed. The organic light emitting device includes an array substrate and a package substrate (2); on a side of the package substrate (2) facing the array substrate, there is provided a protrusion (7) formed of a first transparent material, a surface of the protrusion (7) is also covered with a transparent layer (8) formed of a second transparent material, and the refractive index of the second transparent material is larger than the refractive index of the first transparent material. With the organic light emitting device, a part of light that is emitted from an organic light-emitting layer (5) and irradiated to a surface of the protrusion (7) is totally reflected and changed in optical paths to decrease incident light totally reflected at a boundary between the package substrate (2) and the outside air, and light that has been changed in optical paths is irradiated out through the package substrate (2) more easily, thereby improving the output efficiency of light.