OLED Charge Generation Layer for Luminous Efficiency
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Solution Overview
Problem
Conventional organic light-emitting diodes (OLEDs) face low luminous efficiency due to unbalanced injection of holes and electrons, primarily because of differences in mobility and difficulty in controlling carrier recombination at material interfaces formed by different manufacturing processes.
Innovation Solution
The OLED structure includes a charge generation layer with a first connection layer doped with an electron transport material and a second connection layer doped with a hole transport material, directly contacting the light-emitting layers, which adjusts electron and hole mobility to enhance recombination efficiency, along with specific materials like anthracene derivatives and aromatic diamine compounds for carrier injection, and electron and hole transport layers formed by different processes to balance carrier transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional OLED structure with single light-emitting layer is used, then device structure is simple, but luminous efficiency is low due to unbalanced carrier injection
Solution Approach 1:
The single light-emitting layer is segmented into multiple light-emitting layers (first light-emitting layer and second light-emitting layer) with different emission colors. Each layer is equipped with dedicated electron transport and hole transport layers, creating multiple recombination zones that improve overall luminous efficiency while maintaining reasonable structural complexity.
Solution Approach 2:
Different regions of the device are assigned different functional qualities: the first light-emitting layer emits red light with specific carrier transport characteristics, while the second light-emitting layer emits green light with different transport characteristics. The electron transport layers and hole transport layers are optimized locally for each region to achieve balanced carrier injection and high recombination efficiency.
2Loss of energy
If electron transport layer and hole transport layer are added to balance carrier injection, then luminous efficiency improves, but device structure becomes more complex
Solution Approach 1:
The electron transport layer and hole transport layer are merged into an integrated transport system for each light-emitting layer. The electron transport layer (containing BCP and Alq3) and hole transport layer (containing NPB and TAPC) work synergistically to balance carrier injection, achieving high luminous efficiency while maintaining a unified structural approach that can be replicated across multiple layers.
Solution Approach 2:
The transport layers are designed and positioned in advance to pre-establish balanced carrier injection pathways before the devices operate. The specific material compositions and layer thicknesses are predetermined to ensure optimal carrier balance, eliminating the need for complex real-time adjustments during device operation.
3Illumination intensity
If multiple light-emitting layers with different emission colors are used, then display performance improves, but manufacturing precision requirements increase due to different manufacturing processes
Solution Approach 1:
The manufacturing process parameters are changed and optimized for each light-emitting layer according to its specific requirements. The first light-emitting layer (red emission) and second light-emitting layer (green emission) are fabricated using process conditions tailored to their respective materials and desired performance characteristics, allowing high display performance while managing manufacturing precision through parameter optimization rather than rigid uniformity.
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 configuration improves the luminous efficiency of the OLED by increasing the number of electron and hole pair recombination, resulting in enhanced display performance and reduced voltage requirements while maintaining comparable brightness.
Implementation Method 1
Organic light-emitting diodes (OLEDs) are display devices which emit light by electrically excited fluorescent organic compound or by electrically excited phosphorescence organic compound
Data Source
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Figure 4
AI summary
An organic light-emitting diode, a manufacturing method thereof and a display device are provided. The organic light-emitting diode (100) includes: a base substrate (101), a first electrode (102) and a second electrode (103) disposed on the base substrate (101), a first light-emitting layer (1041) disposed between the first electrode (102) and the second electrode (103), and a charge generation layer (105) disposed between the first light-emitting layer (1041) and the second electrode (103), and the charge generation layer (105) includes a first connection layer (1051), a carrier injection layer (1052) and a second connection layer (1053) which are stacked in sequence; the first connection layer (1051) includes an electron transport material doped with a hole blocking material, and the second connection layer (1053) includes a hole transport material doped with an electron blocking material. The number of recombination of electron and hole pairs in the light-emitting layer is increased by the charge generation layer of the organic light-emitting diode, so that the luminous efficiency is improved.