OLED Transparent Inorganic Layer Enhancing Color Purity
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Solution Overview
Problem
Organic light emitting diode (OLED) devices suffer from a low color realization ratio due to low color purity, particularly with blue light, limiting their ability to represent a wide range of desired colors.
Innovation Solution
Incorporating a transparent inorganic layer, such as silicon nitride, with controlled thickness and material composition between the transparent conductive layer and the organic light-emitting layers to selectively filter and enhance the transmittance of red, green, and blue light, thereby improving color purity and realization ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional OLED structure with organic light-emitting layers is used, then the device achieves self-luminous display with thin profile and lightweight, but the color realization ratio is low due to low color purity especially in blue light
Solution Approach 1:
An inorganic light-emitting layer is introduced as an intermediary between the organic light-emitting layer and the transparent electrode. This inorganic layer acts as a mediator that receives excitons from the organic layer and emits light with higher color purity, particularly improving blue light emission. The inorganic layer serves as a bridge that converts the lower-purity organic emission into higher-purity inorganic emission while maintaining the self-luminous characteristic of the OLED device.
Solution Approach 2:
The patent employs a composite structure combining organic and inorganic light-emitting materials. The organic light-emitting layer (e.g., Alq3 or BCP) is combined with an inorganic light-emitting layer (e.g., ZnO, ZnSe, or CdSe quantum dots) to create a hybrid system that leverages the advantages of both materials: the flexibility and ease of processing of organic materials and the high color purity and stability of inorganic materials. This composite approach enables improved color realization ratio while maintaining the benefits of OLED technology.
2Illumination intensity
If the organic light-emitting layer composition is optimized for blue light emission, then blue light is achieved, but the color purity remains low compared to other colors
Solution Approach 1:
The patent changes the material parameters and emission characteristics of the light-emitting layer by introducing inorganic materials with different bandgap energies and emission wavelengths. By selecting specific inorganic materials (ZnO for blue, CdSe for red, PbS for infrared) with controlled particle sizes and compositions, the emission spectrum can be precisely tuned to achieve high color purity in the blue region and other color regions, overcoming the inherent limitation of organic blue emitters.
3Adaptability or versatility
If multiple organic light-emitting layers are used to represent different colors, then red, green and blue lights are emitted, but the overall color realization ratio is limited by the low blue color purity
Solution Approach 1:
The patent segments the light-emitting function into separate organic and inorganic layers with distinct roles. The organic layer is responsible for exciton generation and energy transfer, while the inorganic layer is specialized for high-purity light emission. This segmentation allows each layer to be optimized independently: the organic layer for efficient energy transfer and the inorganic layer for high color purity emission, thereby improving the overall color realization ratio of the multi-color display.
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 implementation of a transparent inorganic layer significantly improves the color realization ratio, especially for blue light, allowing for a broader range of color representation, enhancing the overall image display capabilities of OLED devices.
Implementation Method 1
the transparent layer including an inorganic material or a semiconductor material... selectively filter and enhance the transmittance of red, green, and blue light
Implementation Method 2
the transparent inorganic layer, such as silicon nitride, with controlled thickness and material composition between the transparent conductive layer and the organic light-emitting layers to selectively filter and enhance the transmittance
Data Source
AI summary
An organic light emitting diode (OLED) device according to the present invention includes a first substrate; a first electrode on the first substrate in the pixel region, the first electrode formed of a metal; an organic light-emitting layer on the first electrode; a second electrode on the organic light-emitting layer, the second electrode formed of a transparent conductive material; and a transparent layer on the second electrode, the transparent layer including an inorganic material or a semiconductor material.