Curved Flexible OLED Light Extraction
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Solution Overview
Problem
Organic light-emitting diodes (OLEDs) suffer from low light extraction efficiency due to total internal reflection and waveguide effects caused by refractive index differences between layers, resulting in only 20% of generated light being emitted outward, while 80% is lost, limiting luminous efficiency.
Innovation Solution
An organic light-emitting device with a flexible OLED having a curved surface, a reflector on non-emission areas, and a light-scattering filler layer with particles, along with transparent electrodes and a light extraction layer, is used to increase the light-emitting area and scattering, enhancing luminance and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar OLED structure is used, then the device structure is simple and easy to manufacture, but the light extraction efficiency is low (only 20% of generated light is emitted outward)
Solution Approach 1:
The patent applies curvature to the OLED structure by forming a convex curved surface on the substrate or encapsulation layers. This curved geometry transforms the planar waveguide structure into a non-planar configuration, enabling light rays that would normally undergo total internal reflection to escape at different angles, thereby improving light extraction efficiency while maintaining manufacturing feasibility through conventional patterning and lamination processes
Solution Approach 2:
The patent introduces a third dimension by creating protruding curved structures on the OLED surface. Instead of relying solely on planar layer thickness variations, the invention adds vertical dimensionality through curved protrusions that extend from the substrate surface, creating multiple light extraction interfaces and pathways that enhance overall light emission without complicating the fundamental planar device architecture
2Illumination intensity
If the light-emitting area is increased to improve luminance, then the luminous efficiency improves, but the device area and complexity increase
Solution Approach 1:
The curved surface configuration increases the effective light-emitting area within a compact footprint. By forming convex curved protrusions, the patent creates additional light extraction surfaces that emit light in multiple directions, effectively increasing the luminous area without proportionally increasing the device's planar footprint, thus improving luminance while controlling device complexity
3Loss of energy
If antireflection films or barrier ribs are added to improve light extraction, then light extraction efficiency improves, but the device structure and manufacturing complexity increase
Solution Approach 1:
The patent merges the structural functions of the substrate, encapsulation layers, and light extraction features into a unified curved structure. Rather than adding separate antireflection films or barrier ribs as distinct components, the invention integrates light extraction functionality directly into the curved geometry of the existing device layers, thereby improving light extraction efficiency while minimizing increases in structural complexity and manufacturing steps
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 flexible OLED configuration with a curved surface and light-scattering particles significantly increases the light-emitting area per unit area, improving luminance and light extraction efficiency, while the reflector and transparent electrodes further enhance luminance by directing and scattering light effectively.
Implementation Method 1
OLEDs are self-emitting light sources based on the radiative decay of excitons in an organic light-emitting layer, the excitons being generated by the recombination of electrons injected through an electron injection electrode (cathode) and holes injected through a hole injection electrode (anode)
Implementation Method 2
when a beam of light generated by the light-emitting layer is emitted at an angle greater than a critical angle, the beam of light may be totally reflected at the interface between a higher-refractivity layer, such as a transparent electrode layer, and a lower-refractivity layer, such as a glass substrate
Implementation Method 3
a light-scattering filler layer with particles, along with transparent electrodes and a light extraction layer, is used to increase the light-emitting area and scattering, enhancing luminance and light extraction efficiency
Data Source
AI summary
The present invention relates to an organic light-emitting device for lighting, and more specifically relates to an organic light-emitting device for lighting whereby it is possible to achieve excellent brightness by increasing the light-emitting area per unit area of an organic light-emitting element. For this purpose, the present invention provides an organic light-emitting device comprising: a first substrate and a second substrate disposed facing each other; a frame section which is formed between the first substrate and the second substrate, and is formed on the periphery of the first substrate and the second substrate so as to hermetically close the space between the first substrate and the second substrate; and a flexible organic light-emitting element which is disposed inside of the space, and of which at least one part has a curved surface.