Organic Light-Emitting Element Dopant Interdiffusion Barrier
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Solution Overview
Problem
Organic light emitting devices face challenges in maintaining driving stability due to chemical reactions and increased driving voltage caused by dopant interdiffusion between layers, which affects device performance and longevity.
Innovation Solution
Incorporating a stacked structure with an undoped first layer, a barrier second layer, and an n-type dopant third layer, along with an additional electron transport layer, to prevent chemical reactions and dopant diffusion, thereby enhancing stability and reducing voltage increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dopant is added to electron transport layer to improve electron injection, then electron transport performance is improved, but dopant interdiffusion between layers occurs causing chemical reactions and increased driving voltage
Solution Approach 1:
The patent introduces an undoped electron transport layer as an intermediary barrier between the doped electron transport layer and the light emitting layer. This intermediary layer prevents direct contact and interdiffusion between dopants in the doped layer and materials in the light emitting layer, thereby eliminating chemical reactions and dopant contamination while maintaining electron transport performance through the doped layer.
Solution Approach 2:
The electron transport function is segmented into multiple distinct layers: a doped electron transport layer for electron injection and transport enhancement, an undoped electron transport layer as a barrier to prevent dopant diffusion, and additional undoped layers positioned strategically. This segmentation allows each layer to perform its specific function without interfering with adjacent layers, preventing harmful interdiffusion while maintaining overall device performance.
2Reliability
If multiple organic material layers are stacked to improve device functionality, then device performance is enhanced, but complexity of layer structure and manufacturing increases
Solution Approach 1:
The undoped electron transport layer serves multiple functions simultaneously: it acts as a physical barrier to prevent dopant diffusion, provides an additional electron transport pathway, maintains energy level alignment between layers, and prevents chemical reactions. This multi-functionality reduces the need for separate specialized layers, thereby managing complexity while enhancing device performance and reliability.
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 structure effectively prevents chemical reactions and dopant interdiffusion, leading to improved driving stability, reduced voltage increase, and enhanced performance with better low voltage, high luminance, and efficiency properties.
Implementation Method 1
a light-emitting element comprising: a first electrode; a second electrode opposed to the first electrode; and an organic light-emitting layer formed between the first electrode and the second electrode, the organic light-emitting layer containing a deuterium-labeled carbazole-based compound
Data Source
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AI summary
The present application describes an organic light emitting device including a first layer, a second layer, and a third layer between a cathode and a light emitting layer or between light emitting units, in which the first layer includes an n-type organic material or metal oxide, the second layer includes a barrier material, and the third layer includes an n-type dopant.