Preliminary Charge Transport Layer for OLED Manufacturing
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Solution Overview
Problem
The existing methods for manufacturing organic light emitting display devices often result in degradation of luminescence characteristics due to the use of electrodes as etching masks for charge transport layers, leading to damage and suboptimal performance.
Innovation Solution
A method involving the formation of a preliminary charge transport layer using processes like slit coating or spin coating, followed by selective etching with solutions like water, acetone, and anisole, and application via printing processes, which allows for the formation of a charge transport layer before the second electrode, improving electrical contact and encapsulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are used as etching masks for charge transport layers, then the manufacturing process is simplified, but luminescence characteristics are degraded due to electrode damage
Solution Approach 1:
The charge transport layer formation process is segmented into two distinct stages: first forming a preliminary charge transport layer using the electrode as mask, then selectively etching this preliminary layer to create the final charge transport layer. This segmentation allows the electrode to serve its masking function without directly damaging the luminescence layer, as the etching is controlled to remove only the preliminary layer in specific regions.
Solution Approach 2:
A preliminary charge transport layer is formed in advance before the selective etching process. This preliminary layer acts as a sacrificial mask that protects the luminescence layer during etching, while still allowing the electrode to function as the primary mask. The preliminary action of forming this protective layer eliminates the direct harmful interaction between the electrode and luminescence characteristics.
2Productivity
If the charge transport layer is formed after the second electrode, then the manufacturing sequence is simplified, but electrical contact efficiency and encapsulation are reduced
Solution Approach 1:
The charge transport layer is formed preliminarily before the second electrode is completely finalized, allowing subsequent encapsulation processes to effectively seal the lower substrate. This preliminary formation enables better electrical contact efficiency while maintaining manufacturing productivity through the selective etching approach that defines precise contact regions.
Solution Approach 2:
The selective etching process creates local variations in the charge transport layer, forming specific contact regions with enhanced electrical properties where needed. This local quality modification improves electrical contact efficiency at critical interfaces while maintaining the overall manufacturing sequence efficiency through controlled, localized processing.
3Area of stationary object
If the preliminary charge transport layer covers the entire first electrode and pixel defining layer, then complete coverage is achieved, but selective etching complexity increases
Solution Approach 1:
The preliminary charge transport layer serves a dual function: it provides complete coverage for protection and acts as its own etching mask. The selective etching process utilizes the layer's own material properties and the electrode geometry to define the final pattern, eliminating the need for separate complex masking processes and reducing overall device complexity despite the initial complete coverage.
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 enhances luminescence characteristics and extends the lifespan of organic light emitting display devices by improving electrical contact efficiency and encapsulating the lower substrate effectively.
Implementation Method 1
The preliminary charge transport layer may be partially etched by an etching solution including at least one of water, acetone and anisole
Implementation Method 2
applying an inert gas on the lower substrate to remove the etching solution remaining on the lower substrate
Data Source
AI summary
A method of manufacturing an organic light emitting structure is provided as follows. A first electrode is formed on a lower substrate. A pixel defining layer is formed adjacent to the first electrode on the lower substrate. A preliminary charge transport layer is formed on the first electrode and the pixel defining layer. An organic light emitting layer is formed on the preliminary charge transport layer. The preliminary charge transport layer is selectively etched to form a charge transport layer. A second electrode is formed on the organic light emitting layer.