Anisotropic Scattering Substrate for OLED Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic electronic devices like OLEDs, a significant amount of light is trapped at the interface between the organic layer and the substrate due to refractive index mismatch, leading to low light emission efficiency in bottom-emitting devices.
Innovation Solution
A substrate with a light-transmissive base layer and a scattering layer featuring anisotropic nanostructures is used, which scatters and diffuses incident light, minimizing wavelength dependence and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional substrate structure with flat interfaces is used, then the device structure is simple, but light extraction efficiency is low due to total internal reflection at interfaces
Solution Approach 1:
The patent introduces curved scattering centers with spherical or spheroidal shapes into the substrate. These curved structures have different refractive indices from the surrounding medium, causing light to scatter when passing through them. The curvature prevents total internal reflection by changing the angle of incidence, thereby improving light extraction efficiency without significantly complicating the manufacturing process.
Solution Approach 2:
The patent modifies the optical parameters of the substrate by incorporating scattering centers with specific refractive indices (e.g., TiO2 with refractive index of 2.54). By changing the refractive index parameter at specific locations within the substrate, the optical path of light is altered, reducing total internal reflection and enhancing light extraction while maintaining structural simplicity.
2Loss of energy
If a scattering layer with isotropic nanostructures is used, then light scattering occurs, but wavelength dependence increases and extraction efficiency is limited
Solution Approach 1:
The patent employs asymmetric scattering centers with specific aspect ratios (e.g., spherical shapes or spheroidal shapes) rather than isotropic structures. This asymmetry in shape creates different scattering patterns for different wavelengths of light, reducing wavelength dependence. The asymmetric geometry ensures that light across a broader spectrum is scattered effectively, improving both extraction efficiency and wavelength independence.
Solution Approach 2:
The patent introduces a new dimensional aspect by creating three-dimensional scattering centers within the substrate rather than using two-dimensional surface structures. The spherical or spheroidal shapes extend into the third dimension, providing scattering pathways that are effective across a broader range of wavelengths and angles, thereby reducing wavelength dependence while maintaining strong scattering capability.
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 substrate design significantly improves light extraction efficiency by scattering light according to the angle of incidence, thereby increasing the performance of organic electronic devices.
Implementation Method 1
A substrate with a light-transmissive base layer and a scattering layer featuring anisotropic nanostructures is used, which scatters and diffuses incident light
Implementation Method 2
By the relationship of the above-described refractive indexes, for example, light generated in the organic light-emitting layer is trapped in an interface between the organic layer and the first electrode layer, or in the substrate by a total internal reflection phenomenon
Data Source
Figure 1~4
Figure 5~6
Figure 6
AI summary
The present application relates to a substrate for an organic electronic device, an organic electronic device, and a lighting device. In an embodiment of the present application, a substrate or an organic electronic device which may form an organic electronic device capable of ensuring performance including light extraction efficiency or the like and reliability by applying a scattering layer capable of exhibiting different scattering properties according to an angle of incident light may be provided.