Organic Light-Emitting Display Buffer Layer Refractive Index Optimization
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Solution Overview
Problem
Organic light-emitting display devices have lower light coupling efficiency compared to other display technologies, such as cathode-ray tubes and plasma display panels, necessitating improvements in luminance and lifetime.
Innovation Solution
The implementation of an organic light-emitting display device with a buffer layer and insulation layers having sequentially stacked materials with different refractive indexes, along with specific electrode and active layer configurations, to achieve an optical resonance effect, thereby enhancing light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-layer buffer and insulation structures are used, then manufacturing process is simpler, but light coupling efficiency is low
Solution Approach 1:
The buffer layer and insulation layer are divided into multiple sub-layers with different refractive indexes. The buffer layer includes a first buffer layer and a second buffer layer, while the insulation layer includes a first insulation layer and a second insulation layer. This segmentation allows optimization of light coupling efficiency through refractive index matching while maintaining manufacturing feasibility through systematic layer-by-layer deposition processes.
Solution Approach 2:
The patent employs composite material structures where each layer is made of materials with specifically selected refractive indexes. The buffer layer uses materials with refractive indexes ranging from 1.4 to 2.0, and the insulation layer uses materials with refractive indexes ranging from 1.3 to 1.8. This composite approach creates optimal optical conditions for light coupling efficiency while allowing standard semiconductor manufacturing processes to be used.
2Manufacturing precision
If multiple masks are used for pattern transfer, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the pattern transfer function into the existing multi-layer deposition process. The thin film transistor pattern is formed by sequentially depositing the buffer layer, active layer, insulation layer, and electrode layers, each with its own material composition and refractive index characteristics. This integration eliminates the need for separate mask-based pattern transfer steps, reducing device complexity while maintaining the precision required for thin film transistor fabrication.
Solution Approach 2:
Each deposited layer serves multiple functions: the buffer layer provides both mechanical support and optical refractive index management, the insulation layer provides both electrical isolation and optical resonance enhancement, and the electrode layers provide both electrical connectivity and optical characteristics. This multi-functionality reduces the need for dedicated pattern transfer masks while achieving both structural and optical objectives.
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 increases light efficiency and color reproduction range while reducing the number of masks required in the manufacturing process, lowering costs and simplifying production.
Implementation Method 1
the light efficiency of an organic light-emitting display device is classified into internal efficiency and external efficiency. Here, the internal efficiency depends on photoelectric conversion efficiency of an organic light-emitting material, and the external efficiency depends on a refractive index of each layer forming the organic light-emitting display device. Here, since the organic light-emitting display device has lower light coupling efficiency, i.e., the external efficiency, than other display devices
Data Source
AI summary
An organic light-emitting display device includes: a buffer layer including sequentially stacked materials having different refractive indexes on a substrate; source and drain electrodes on the buffer layer; a first active layer of a thin film transistor between the source and drain electrodes, and a second active layer spaced from the first active layer at a same layer as and including a same material as the first active layer; a first insulation layer on the buffer layer, the source and drain electrodes, the first and second active layers, and including sequentially stacked materials having different refractive indexes; a first gate electrode corresponding to a center region of the first and second active layers with the first insulation layer therebetween, and a pixel electrode at a same layer as and comprising a same material as the first gate electrode; and a second gate electrode on the first gate electrode.