Organic Hole Transport Layer Segmentation for OLED Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for manufacturing light emitting devices, which involve a combination of coating and vapor deposition for the hole transport layer, result in decreased hole mobility, leading to degraded light emission efficiency.
Innovation Solution
A method involving multiple coating and deposition steps for forming hole injection, first, second, and third hole transport layers, and a light emitting layer, with specific materials and techniques to maintain hole mobility, including the use of different materials and methods for the second and third hole transport layers to create an interface that maintains refractive index differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a portion of the hole transport layer is formed by coating method and the remaining layer is formed by vapor deposition method, then the manufacturing process can be simplified and productivity improved, but hole mobility decreases and light emission efficiency degrades
Solution Approach 1:
The hole transport layer is divided into three distinct sub-layers (first hole transport layer, second hole transport layer, and third hole transport layer), each formed by different methods. The first and second hole transport layers are formed by coating method to improve productivity, while the third hole transport layer is formed by vapor deposition method to maintain high hole mobility and prevent efficiency degradation at the interface with the light emitting layer.
Solution Approach 2:
Different regions of the hole transport layer are assigned different formation methods based on their functional requirements. The lower portions (first and second hole transport layers) use coating method for efficiency, while the upper portion adjacent to the light emitting layer (third hole transport layer) uses vapor deposition method to ensure optimal hole mobility and interface quality, thereby maintaining light emission efficiency.
2Reliability
If multiple coating and deposition steps are used to form different hole transport layers, then hole mobility is maintained and light emission efficiency is preserved, but device complexity increases
Solution Approach 1:
The hole transport layer is segmented into three sub-layers with distinct formation methods. This segmentation allows the use of coating method for the first two layers (simpler process) and vapor deposition method for the third layer (maintains performance), balancing complexity and performance requirements.
Solution Approach 2:
The formation method parameter is changed across different layers of the hole transport layer. By varying the deposition parameters (coating vs. vapor deposition) based on position and functional requirements, the patent achieves optimal hole mobility while managing manufacturing complexity through systematic parameter variation.
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 approach effectively suppresses the degradation of light emission efficiency and extends the lifespan of the light emitting device by maintaining hole mobility and luminance over time.
Implementation Method 1
a first step of coating a hole injection material, a second step of coating a first hole transporting material after the first step, a third step of coating a second hole transporting material after the second step
Implementation Method 2
a fourth step of depositing the second hole transporting material after the third step, and a fifth step of depositing a light emitting material after the fourth step
Data Source
AI summary
A light emitting device (10) includes a hole injection layer (121), a hole transport layer (122), and a light emitting layer (123). The hole transport layer (122) includes a first organic layer (122a), a second organic layer (122b), and a third organic layer (122c). The first organic layer (122a) is formed on the hole injection layer (121) and includes a first hole transporting material. The second organic layer (122b) is formed on the first organic layer (122a) and includes a second hole transporting material. The third organic layer (122c) is formed on the second organic layer (122b) and includes the second hole transporting material. The second organic layer (122b) is formed by using a coating method, and the third organic layer (122c) is formed by a vapor deposition method.