OLED Light-Emitting Layers with Local Thickness Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic light-emitting display devices face challenges in manufacturing efficiency due to the need for multiple steps and precise deposition processes, which increase costs and risk of pixel defects, especially when using masks with fine patterns for different color layers.
Innovation Solution
An organic light-emitting display device design where the distances from light-emitting layers to upper electrodes and film thicknesses between reflecting electrodes are the same across blue, green, and red light-emitting portions, allowing for simplified manufacturing with reduced steps and precision in deposition, using materials like Al for lower electrodes and tris(8-hydroxyquinolinato)aluminum for electron transport layers, and maintaining high accuracy within ±7% error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If different film thicknesses are used for ITOs in blue, green, and red light-emitting portions to increase light emission efficiency, then light emission efficiency is improved, but the number of manufacturing steps increases requiring two additional deposition steps and two additional photolithography patterning steps
Solution Approach 1:
The patent applies local quality by forming the first organic layer with different thicknesses in different light-emitting portions (blue, green, red) to optimize light emission efficiency for each color. The thickness varies locally according to the specific color requirements while using a single unified deposition process without additional patterning steps.
2Loss of energy
If different film thicknesses are used for organic layers in blue, green, and red light-emitting portions to increase light emission efficiency, then light emission efficiency is improved, but at least two additional deposition steps are required with precise mask alignment
Solution Approach 1:
The patent forms the first organic layer with different thicknesses in different light-emitting portions through a single deposition process. The thickness is locally optimized for each color (blue, green, red) without requiring multiple deposition steps or precise mask alignment, thereby maintaining manufacturing precision while achieving improved light emission efficiency.
3Manufacturing precision
If masks with fine patterns are used for precise deposition in light-emitting portions, then deposition precision is improved, but the process time increases due to extra alignment time and risk of pixel defects increases
Solution Approach 1:
The patent extracts and eliminates the need for masks with fine patterns and their associated alignment processes. By using a single deposition process that forms the first organic layer with different thicknesses in different light-emitting portions without masks, the method removes the source of alignment time consumption and pixel defect risks while maintaining the required deposition precision.
4Loss of energy
If multiple deposition steps with masks are used to achieve different film thicknesses, then light emission efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent achieves local quality optimization by forming the first organic layer with different thicknesses in different light-emitting portions through a single deposition process. This approach maintains high light emission efficiency for each color while significantly reducing manufacturing cost by eliminating the need for multiple deposition steps and associated masks.
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 maintains light emission efficiency for blue, green, and red colors without increasing the number of deposition steps, reducing the risk of pixel defects and manufacturing time, while enabling a cost-effective and high-efficiency production process.
Implementation Method 1
an organic layer including a hole transport layer, a light-emitting layer and an electron transport layer
Implementation Method 2
a reflecting electrode having a low work function. Emitted light is transmitted through the transparent electrode and is taken from the bottom of the glass substrate
Implementation Method 3
a transparent electrode made of ITO or the like. Emitted light is transmitted through the transparent electrode
Data Source
AI summary
An organic light-emitting display device is provided which achieves high efficiency by reducing the number of steps for vapor deposition using a mask with a fine pattern and photolithography. A blue light-emitting portion (B), a green light-emitting portion (G) and a red light-emitting portion (R) placed on a substrate 10 have a thickness relationship represented as (blue light-emitting portion (B)<green light-emitting portion (G)=red light-emitting portion (R)), so that the green light-emitting portion (G) and the red light-emitting portion are formed with common deposition steps. In addition, an electron injection layer 2 and an electron transport layer 3 between a lower electrode and an organic light-emitting layer 4 are formed with common depositions steps in the light-emitting portions (B, G and R).