OLED Scattering Layer for Light Outcoupling Efficiency
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Solution Overview
Problem
Current organic light-emitting diodes (OLEDs) face challenges in achieving high outcoupling efficiency due to internal and total reflection losses, leading to only about 25% of emitted light being output, with existing solutions like micro lenses arrays being costly and inefficient.
Innovation Solution
Incorporating a scattering layer made from a specific chemical compound with no measurable glass transition temperature, forming rough crystallized layers outside the electronically active region, which enhances light outcoupling without increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a scattering layer is added to improve light outcoupling, then light extraction efficiency is improved, but device structure complexity increases
Solution Approach 1:
The patent combines the scattering function and electron transport function into a single layer. The scattering layer is formed by thermal evaporation of a compound (e.g., Alq3) that simultaneously provides electron transport capability and light scattering through its rough crystallized morphology, eliminating the need for separate electron transport and scattering layers.
Solution Approach 2:
The scattering layer material serves multiple functions: it acts as an electron transport material, provides light scattering through its rough morphology, and maintains device performance. This multi-functional approach allows one layer to fulfill what would traditionally require multiple separate layers.
2Loss of energy
If micro lenses array is used to improve outcoupling, then light extraction efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive micro lenses array with a simple thermally evaporated organic layer that forms a rough morphology. This approach uses inexpensive materials and standard thermal evaporation equipment already present in OLED manufacturing, avoiding the need for costly micro lens fabrication and integration processes.
Solution Approach 2:
The invention changes the physical parameters of the scattering layer by controlling the thermal evaporation process to form a rough crystallized morphology. By adjusting deposition conditions and material selection, the layer develops intrinsic scattering properties without requiring additional optical components.
3Reliability
If multiple layers are individually thermally vapour-deposited, then device performance is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple functions into fewer layers. Specifically, the scattering layer is deposited in a single thermal evaporation step and simultaneously provides electron transport and light scattering functions, reducing the total number of deposition steps while maintaining device performance.
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 significantly improves light outcoupling efficiency while maintaining a simple device structure and manufacturing method, achieving higher performance and cost-effectiveness for OLEDs, particularly in large-area lighting applications.
Implementation Method 1
a glass transition temperature of below 40° C., more preferred is a Tg<40° C., even more preferred is a Tg<0° C., in particular no measurable glass transition temperature. The material does not present a Tg at all under conventional measurements. Furthermore, the material does not form amorphous layers (for instance by using VTE or OVPD).
Implementation Method 2
a scattering layer having a thickness of less than 50 nm
Data Source
AI summary
The present invention relates to an organic light emitting device that includes a layered structure including a substrate, a bottom electrode and a top electrode, wherein the bottom electrode is closer to the substrate than the top electrode, the region between the bottom electrode and the top electrode defining an electronically active region, wherein the electronically active region includes a scattering layer having a thickness of less than 50 nm; and an organic light emitting device additionally having at least one light emitting layer in the electronically active region, and this device can also include a specific chemical compound outside of the electronically active region.