Uneven Nanoparticle Layer for OLED Light Extraction
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Solution Overview
Problem
Existing OLED devices suffer from low light extraction efficiency due to total reflection of photons at the interface between the glass substrate and air, resulting in reduced brightness and viewing angle.
Innovation Solution
A method for preparing an uneven particle layer using nanoparticles made of transparent polymer materials, such as polystyrene or polymethacrylate, is applied to the substrate, where the nanoparticles are fused by heating to create a surface with reduced total reflection, allowing more light to escape into the air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat glass substrate is used in OLED devices, then the device structure is simple and easy to manufacture, but total reflection occurs at the interface between the glass substrate and air, reducing light extraction efficiency
Solution Approach 1:
The patent applies spherical nanoparticles (400-700 nm in diameter) to the glass substrate surface to create a curved microstructure. These spherical particles act as microlenses that refract and redirect light rays, preventing total internal reflection and improving light extraction efficiency without complicating the manufacturing process
Solution Approach 2:
The patent modifies the surface parameters of the glass substrate by coating it with nanoparticles of specific sizes (400-700 nm). This parameter change in surface topology transforms the optical properties at the interface, reducing reflection losses while maintaining manufacturing simplicity
2Loss of energy
If the nanoparticle layer is heated to fuse particles, then light extraction efficiency improves, but energy is consumed during the heating process
Solution Approach 1:
The patent utilizes the phase transition of nanoparticles from solid to fused state through controlled heating. This phase transition creates the optimal surface morphology for light extraction, and the heating is applied only during the manufacturing process, not during device operation
Solution Approach 2:
The heating and fusion of nanoparticles is performed as a preliminary step during device manufacturing. This preliminary action prepares the optimal surface structure before the OLED is assembled and put into operation, so no additional energy is consumed during the device's operational lifetime
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 method enhances light extraction efficiency and brightness, improving the viewing angle of OLED devices by altering the propagation direction of rays and reducing total reflection, making the technology suitable for various display devices.
Implementation Method 1
the transparent polymer material has a glass transition temperature of T 1 and the heating temperature is T 1 to T 1 +50 °C
Implementation Method 2
heating the substrate to fuse nanoparticles that are in contact with the substrate
Implementation Method 3
the photon is reflected and refracted on an interface of an incident medium (the incident medium in Fig.1 is a glass substrate, and the incident in Fig.2 medium is a semitransparent cathode) and the air
Implementation Method 4
When the incidence angle is greater than or equal to a critical angle, total reflection occurs, and rays cannot be emitted to the air
Data Source
Figure 1~3
Figure 4~5
AI summary
The present invention provides a method for preparing an uneven particle layer, an organic light emitting diode device and a display device. The method for preparing an uneven particle layer includes the following steps: forming a nanoparticle layer on a substrate; heating the substr ate to fuse nanoparticles that are in contact with the substrate, whereas the nanoparticles on the su rface keep a solid state; and cooling the substrate to form a nanoparticle layer with an uneven surface. The method of the present invention is simple in process, and industrial production is easy to achieve. The substrate including the uneven particle layer is applied to the OLED device, so the propagation direction of rays from the organic light emitting layer of the OLED device can be changed so as to avoid total reflection on an interf ace, emit more light into the air and improve the light extraction efficiency of the OLED device. The OLED device prepared in the present invention is suitable for various display devices.