Light-emitting Device Optical Path Length Adjustment
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Solution Overview
Problem
The existing electroluminescent (EL) display devices face challenges in achieving high-definition displays with high color purity and low power consumption due to the complexity of selective deposition processes and potential defects caused by metal masks during manufacturing.
Innovation Solution
The solution involves adjusting the optical path length between electrodes and light-emitting layers using color filter layers, allowing for the stacking of light-emitting layers without selective deposition, which enhances color purity and productivity by optimizing the optical path lengths in relation to the central wavelengths of the color filter layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selective deposition of light-emitting materials is performed using a metal mask for each pixel, then light-emitting elements can be formed with different colors, but shape defects or emission defects may occur due to contact between the metal mask and the pixel electrode
Solution Approach 1:
An insulating layer is introduced as an intermediary between the metal mask and the pixel electrode during the evaporation process. This insulating layer prevents direct contact between the metal mask and the electrode, thereby eliminating shape defects and emission defects while still allowing selective deposition of light-emitting materials through the mask pattern.
2Adaptability or versatility
If selective deposition of light-emitting materials is performed for each pixel by evaporation method using a metal mask, then full-color display can be achieved, but the process becomes complicated and productivity decreases
Solution Approach 1:
The patent merges the color filtering function into a separate color filter layer that is applied over the entire light-emitting layer, rather than requiring selective deposition of different colored materials for each pixel. This combining of functions allows full-color display while dramatically simplifying the manufacturing process and improving productivity.
Solution Approach 2:
The solution moves from a lateral differentiation approach (selective deposition of different materials in different pixel locations) to a vertical stratification approach (single light-emitting layer with color filtering in a separate dimension). This dimensional shift enables full-color display without complex selective deposition processes.
3Measurement precision
If the optical path length between the electrode and light-emitting layer is adjusted by the central wavelength of the color filter layer, then high color purity and high-definition display can be achieved, but the structure becomes more complex
Solution Approach 1:
The patent optimizes the optical path length as a critical parameter to achieve high color purity. By carefully controlling the thickness of the light-emitting layer and the optical path between the electrode and light-emitting layer relative to the central wavelength of the color filter, the system achieves enhanced color purity and high-definition display without requiring additional complex structural elements.
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 enables the production of high-definition display devices with improved color purity and reduced power consumption by eliminating the need for selective deposition and minimizing defects, while simplifying the manufacturing process.
Implementation Method 1
the optical path length between an electrode having a reflective property and a light-emitting layer is adjusted by a central wavelength of a color filter layer
Implementation Method 2
an electrode having a reflective property and a light-emitting layer... the optical path length between the first electrode having a reflective property and the first light-emitting layer
Data Source
AI summary
A technique of manufacturing a display device with high productivity is provided. In addition, a high-definition display device with high color purity is provided. By adjusting the optical path length between an electrode having a reflective property and a light-emitting layer by the central wavelength of a wavelength range of light passing through a color filter layer, the high-definition display device with high color purity is provided without performing selective deposition of light-emitting layers. In a light-emitting element, a plurality of light-emitting layers emitting light of different colors are stacked. The closer the light-emitting layer is to the electrode having a reflective property, the longer the wavelength of light emitted from the light-emitting layer is.