Organic Light Emitting Element High Refractive Index Scattering Layer
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Solution Overview
Problem
Existing organic light emitting elements suffer from low light extraction efficiency, leading to high power consumption and reduced lifespan due to significant light loss at the interface between the transparent electrode and air, which current diffusion and scattering layers fail to adequately address.
Innovation Solution
A light extraction layer with microscopic particles of refractive index 2 or higher, supported by a thin film, is formed on the transparent electrode, increasing the refractive index to 1.4 or higher at the interface and scattering light effectively into the air layer, enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light extraction layer with low refractive index particles is used, then the manufacturing cost is reduced, but the light emission efficiency remains low due to insufficient light scattering
Solution Approach 1:
The patent changes the refractive index parameter of the particles in the light extraction layer from conventional low values (1.4-1.6) to high values (2.0 or higher). This parameter change enables effective light scattering and extraction while maintaining manufacturing feasibility through the use of commercially available high refractive index materials such as titanium oxide, zirconium oxide, and barium titanate.
Solution Approach 2:
The patent creates a composite light extraction layer by combining high refractive index particles (titanium oxide, zirconium oxide, barium titanate) with a transparent resin matrix. This composite structure achieves both high light extraction efficiency through the particles and proper mechanical properties through the resin, while remaining manufacturable using conventional coating techniques.
2Loss of energy
If the refractive index of the light extraction layer is increased to 1.4 or higher, then light emission efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs inexpensive, readily available high refractive index particles (titanium oxide, zirconium oxide, barium titanate) that can be purchased as commercial powders. These particles are mixed with transparent resin in simple ratios and applied using conventional coating methods, avoiding complex manufacturing processes while achieving the desired refractive index of 1.4 or higher.
Solution Approach 2:
The patent achieves the target refractive index by controlling the particle concentration and size distribution in the light extraction layer. By adjusting these parameters within conventional manufacturing ranges, the desired optical performance is obtained without requiring complex multi-step fabrication processes.
3Loss of energy
If high refractive index particles are used in the light extraction layer, then light scattering efficiency is improved, but the material selection and processing difficulty increase
Solution Approach 1:
The patent combines high refractive index particles (titanium oxide, zirconium oxide, barium titanate) with a transparent resin to form a composite light extraction layer. The resin matrix provides mechanical integrity and ease of processing, while the particles provide the light scattering function. This composite approach maintains manufacturing simplicity despite using advanced particles.
Solution Approach 2:
The patent applies the light extraction layer with high refractive index particles specifically at the critical interface where light extraction occurs (between the organic light emitting element and the external environment). This localized application of high-performance materials maximizes light scattering efficiency where it is most needed while keeping the rest of the structure simple and easy to manufacture.
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
This solution significantly increases light emission efficiency, reducing power consumption and prolonging the lifespan of organic light emitting elements by effectively scattering light into the air layer, outperforming previous technologies in terms of efficiency and practical application.
Implementation Method 1
microscopic particles for scattering light is provided on top of the second electrode
Implementation Method 2
the average index of refraction of a light extraction layer formed on the above described transparent electrode is 1.4 or higher
Implementation Method 3
most of the emitted light is totally reflected in the interface between the transparent electrode and the air layer and guided through the organic layer or transparent electrode layer
Data Source
AI summary
An object of the present invention is to provide an organic light emitting element where light emitted from the light emitting layer is efficiently emitted to the outside, and thus, the efficiency of light emission is higher. The present invention provides an organic light emitting element where a first reflective electrode 22, an electron transport layer 23, a light emitting layer 24, a hole transport layer 25, a hole injection layer 26 and a second transparent electrode 27 are formed on a glass substrate 21, and a light extraction layer 28 having an average index of refraction of 1.4 made of titanium particles having an index of refraction of 2.6 and an average particle diameter of 150 nm and silica sol.