Organic Electronic Substrate with Scattering Layer
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Solution Overview
Problem
Existing organic electronic devices face challenges in light extraction efficiency and uniform voltage application due to surface resistance issues and total reflections within the device, which degrade emission efficiency and brightness.
Innovation Solution
A substrate with a scattering layer and planarizing layer is developed, featuring a conductive pattern and scattering particles with a refractive index difference to reduce surface resistance and enhance light extraction, along with a method involving chemical vapor deposition or sol-gel coating for layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional glass substrate with conductive strands and high-k material is used, then the device structure is established, but light extraction efficiency is poor due to total reflections within the device
Solution Approach 1:
The scattering layer is applied locally at the bottom electrode region where light extraction is most problematic. By creating an uneven surface structure with scattering particles in this specific area, light is scattered in multiple directions, preventing total internal reflection and improving extraction efficiency without modifying the entire device structure
Solution Approach 2:
The scattering layer acts as an intermediary between the bottom electrode and the organic light-emitting layers. This intermediate layer with refractive index mismatch scatters light that would otherwise be trapped by total reflection, mediating the optical interaction and enabling improved light extraction from the device
2Illumination intensity
If the substrate structure is modified to improve light extraction, then light extraction efficiency improves, but device performance may decrease due to non-uniform voltage application
Solution Approach 1:
The conductive pattern is applied locally to the bottom electrode in regions where voltage uniformity is needed, rather than uniformly across the entire electrode. This localized conductive network provides preferential current pathways that ensure uniform voltage distribution across the light-emitting area, maintaining device performance while allowing the scattering layer to improve light extraction
Solution Approach 2:
The bottom electrode is segmented into multiple conductive strands or patterns rather than being a continuous uniform layer. This segmentation creates distributed current pathways that prevent localized current crowding and ensure uniform voltage application across the device, while still allowing the scattering layer to function effectively in improving light extraction
3Reliability
If surface resistance is reduced to improve voltage uniformity, then voltage application becomes more uniform, but manufacturing complexity increases
Solution Approach 1:
The bottom electrode is constructed as a composite structure combining a continuous reflective layer (such as aluminum) with a patterned conductive oxide layer (such as ITO). This composite structure leverages the high conductivity of the oxide pattern for voltage uniformity while the continuous metal layer provides low overall resistance and reflectivity, achieving voltage uniformity without excessive manufacturing complexity
Solution Approach 2:
The scattering layer serves multiple functions simultaneously: it scatters light to improve extraction efficiency, and its conductive pattern provides preferential current pathways for uniform voltage application. This multi-functionality reduces the need for separate components, simplifying the overall device structure while achieving both optical and electrical performance goals
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 improves light extraction efficiency and maintains device performance with uniform voltage application, reducing surface resistance and enhancing emission uniformity.
Implementation Method 1
a scattering layer which is formed on the base substrate and includes an conductive pattern for reducing surface resistance of an electrode, scattering particles for scattering light
Implementation Method 2
a planarizing layer which is formed on the scattering layer and flattens surface undulations caused by the uneven structure of the scattering layer
Implementation Method 3
a scattering layer which is formed on the base substrate and includes an conductive pattern for reducing surface resistance of an electrode
Data Source
Figure 1~2(D)
Figure 3
AI summary
The present invention relates to a substrate for an organic electronic element that enables surface resistance to be reduced and light-extraction efficiency improved, the substrate including: a base substrate; a scattering layer which is formed on the base substrate and includes an conductive pattern for reducing the surface resistance of an electrode, scattering particles for scattering light and a binder, and which forms an uneven structure in the surface opposite the base substrate; and a planarizing layer which is formed on the scattering layer and flattens the surface undulations caused by the uneven structure of the scattering layer, wherein the refractive index (Na) of the scattering particles and the refractive index (Nb) of the planarizing layer satisfy the relationship in formula 1 below. [Formula 1] |Na-Nb|≥0.3. In the formula as used herein, Na signifies the refractive index of the scattering particles and Nb signifies the refractive index of the planarizing layer.