Organic Light-Emitting Layer Segmentation for White Emission
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Solution Overview
Problem
Current white light-emitting elements using organic compounds face challenges with luminous efficiency and lifetime, which are inadequate for practical applications.
Innovation Solution
A light-emitting element structure is developed with a first light-emitting layer divided into two layers on either side of the electrodes, containing specific organic compounds and substances, and a second light-emitting layer in contact with the first, to control carrier recombination and enhance luminous efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple organic compounds with different emission colors are combined to achieve white light emission, then broad spectrum emission is obtained, but luminous efficiency and lifetime deteriorate
Solution Approach 1:
The light-emitting layer is divided into multiple sub-layers, each containing a different organic compound (first, second, third organic compounds) with distinct emission characteristics. This segmentation allows each layer to contribute to the overall broad spectrum emission while maintaining optimized carrier recombination in each sub-layer, thereby preserving luminous efficiency and lifetime.
Solution Approach 2:
Different regions of the light-emitting layer are assigned different organic compounds with specific emission properties. The first organic compound emits in one wavelength range, the second in another, and the third in a third range, creating local quality variations that collectively produce white light while maintaining high efficiency in each region.
2Reliability
If a simple single-layer structure is used, then device complexity is reduced, but the ability to achieve both high luminous efficiency and long lifetime in white light emission is limited
Solution Approach 1:
The light-emitting layer is divided into multiple sub-layers, each containing a different organic compound (first, second, third organic compounds) with distinct emission characteristics. This segmentation allows each layer to contribute to the overall broad spectrum emission while maintaining optimized carrier recombination in each sub-layer, thereby preserving luminous efficiency and lifetime.
Solution Approach 2:
The multi-layer structure serves multiple functions simultaneously: each layer contributes to broad spectrum emission, carrier injection is optimized across layers, and overall device stability is enhanced. The first, second, and third organic compounds each perform specific emission functions while collectively achieving white light emission with high efficiency and long lifetime.
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 structure achieves high luminous efficiency and extended lifetime, suitable for broad spectrum and white light emission, making it suitable for display and lighting applications.
Implementation Method 1
Light-emitting elements using electroluminescence... By applying voltage to this element, light emission from the light-emitting substance can be obtained... by recombination of these carriers (electrons and holes), the light-emitting substance forms an excited state, and emits light when the excited state returns to a ground state
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
To provide a long lifetime light-emitting element, in particular, to provide a long lifetime white light-emitting element, and to provide a light-emitting element having high luminous efficiency, in particular, to provide a white light-emitting element having high luminous efficiency. In a light-emitting element having, between an anode (101) and a cathode (102), a first light-emitting layer (111) containing a first light-emitting substance and a second light-emitting layer (112) containing a second light-emitting substance which is provided to be in contact with the first light-emitting layer, the first light-emitting layer (111) is divided into a layer (121) provided on the anode side and a layer (122) provided on the cathode side. At this time, a host material having a hole-transporting property is used for the layer provided on the anode side, and a host material having an electron-transporting property is used for the layer provided on the cathode side.