Light-Emitting Device with Color Conversion Layer
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Solution Overview
Problem
Existing light-emitting devices face challenges in achieving high emission efficiency, long lifetime, low driving voltage, and high reliability, particularly when used in display and lighting applications.
Innovation Solution
A light-emitting apparatus comprising a first light-emitting device and a first color conversion layer, where the color conversion layer contains a substance that absorbs light and emits light, and the light-emitting device includes an anode, a cathode, and an EL layer with specific organic compounds to enhance emission efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a color conversion layer utilizing photoluminescence is used to change light wavelength, then energy loss is reduced compared to blocking light, but the device complexity increases due to additional layers and substances
Solution Approach 1:
A color conversion layer containing photoluminescent substances is introduced as an intermediary component between the light-emitting device and the external environment. This layer converts light of one wavelength to light of desired wavelength through photoluminescence, reducing energy loss compared to direct light blocking while managing the complexity through functional integration
Solution Approach 2:
The patent utilizes photoluminescence parameter changes where substances in the color conversion layer absorb light at specific wavelengths and emit light at different wavelengths. By controlling the photoluminescence properties of the substances, the system achieves efficient wavelength conversion with manageable device complexity
2Loss of energy
If light-emitting devices emit lights of different colors separately, then emission efficiency is improved due to small light loss, but manufacturing complexity and cost increase
Solution Approach 1:
The patent employs a universal light-emitting device that can emit light of a single wavelength but uses a color conversion layer with multiple photoluminescent substances to generate different colors. This approach maintains high emission efficiency by avoiding separate light-emitting devices for each color while achieving multi-color output through the color conversion layer
Solution Approach 2:
The color conversion layer is formed using composite materials containing multiple photoluminescent substances that can be excited by light from the light-emitting device. These composite materials convert the incident light to different wavelengths, enabling multi-color emission with high efficiency and manageable manufacturing complexity
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 proposed solution achieves high emission efficiency, extends the device's lifetime, reduces driving voltage, and enhances the reliability of light-emitting devices, making them suitable for various display and lighting applications.
Implementation Method 1
a color conversion layer utilizing photoluminescence is used. The color conversion layer includes substances that are excited to emit light by absorbing light
Implementation Method 2
Light-emitting devices (organic EL devices) including organic compounds and utilizing electroluminescence (EL) have been put to more practical use. Carriers are injected by application of voltage to the element, and recombination energy of the carriers is used, whereby light emission can be obtained from the light-emitting material
Data Source
AI summary
A long-lifetime light-emitting device is provided. The light-emitting apparatus includes a first light-emitting device and a first color conversion layer. The first color conversion layer contains a first substance. An EL layer of the first light-emitting device includes a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in this order from the anode side. The first layer contains a first organic compound and a second organic compound. The second layer contains a third organic compound. The third layer contains a fourth organic compound. The light-emitting layer contains a fifth organic compound and a sixth organic compound. The fourth layer contains a seventh organic compound. The first organic compound is an organic compound having an electron accepting property to the second organic compound. The fifth organic compound is an emission center substance. The HOMO level of the second organic compound is higher than or equal to −5.7 eV and lower than or equal to −5.4 eV.