OLED Fabrication Using Thermal Transfer for Red and Green Emission Layers
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Solution Overview
Problem
Current methods for fabricating organic light emitting diode (OLED) displays face challenges in achieving large-sized screens with high resolution and low cost, while also dealing with complex processes, low yield, and issues like the coffee stain effect and rough edges due to repeated laser irradiation and transfer film attachment in laser-induced thermal imaging.
Innovation Solution
A method involving the sequential formation of red and green organic emission layers using heat-generating elements on separate substrates, where voltage application enables simultaneous transfer of these layers to a common substrate, followed by deposition of a blue layer, with controlled energy levels to prevent color mixing and enhance luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If laser induced thermal imaging method is used to form emission layers, then large-sized screen and high resolution can be achieved, but the fabrication process becomes complex and time-consuming due to repeated laser irradiation and transfer film attachment
Solution Approach 1:
The patent divides the emission layer formation process into separate stages: first forming red and green emission layers on a transfer substrate, then transferring them to the display substrate, and finally forming the blue emission layer directly on the display substrate. This segmentation eliminates the need for repeated transfer film attachment and laser irradiation, simplifying the overall fabrication process while maintaining large screen capability
Solution Approach 2:
The patent performs preliminary formation of red and green emission layers on a transfer substrate before final transfer to the display substrate. This preliminary action allows these layers to be pre-prepared and then transferred in a single operation, reducing the number of repeated laser irradiation and attachment steps required in conventional methods
2Ease of manufacture
If conventional emission layer formation methods are used, then fabrication process is simpler, but yield is low due to mask blocking phenomenon
Solution Approach 1:
The patent extracts and eliminates the metal fine mask from the fabrication process by using direct thermal field emission and transfer film methods. This removal of the mask component prevents the mask blocking phenomenon that causes low yield, while maintaining ease of manufacture through simplified process steps
3Area of stationary object
If ink jet method is used to form emission layers, then large-sized screen and high definition can be achieved, but cost increases due to need for high speed jetting and multiple heads
Solution Approach 1:
The patent uses a transfer substrate that can be prepared once and reused multiple times for transferring emission layers. This disposable transfer substrate approach is cheaper than developing expensive high-speed ink jet heads with multiple nozzles, while still enabling large screen fabrication
4Manufacturing precision
If repeated laser irradiation is applied to transfer emission layers, then emission layers can be formed on display substrate, but edges become rough due to thermal denaturalization of organic materials
Solution Approach 1:
The patent forms the red and green emission layers on a transfer substrate first, allowing them to be pre-stabilized before transfer to the display substrate. This preliminary formation acts as a cushioning step that protects the organic materials from repeated thermal stress during the final transfer, preventing edge roughness
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 simplifies the fabrication process, reduces time, and improves luminous efficiency and lifespan of OLEDs by forming red, green, and blue layers efficiently, with accurate color display and reduced thermal denaturalization of organic materials.
Implementation Method 1
heat-generating elements at positions on a second substrate, corresponding to red pixels on the first substrate, and at positions on a third substrate, corresponding to green pixels on the first substrate
Implementation Method 2
a laser induced thermal imaging (LITI)
Data Source
AI summary
A method of fabricating an OLED display, includes sequentially forming a TFT array, first electrodes, and a first related layer on a first substrate, respectively forming heat-generating elements on second and third substrates, forming a red organic emission pattern on the second substrate, and forming a green organic emission pattern on the third substrate, aligning and attaching the first and second substrates, applying a voltage to heat-generating elements to transfer the red organic emission pattern to red pixel regions, thereby forming red organic emission layers, aligning and attaching the first and third substrates, applying a voltage to the heat-generating elements to transfer the green organic emission pattern to green pixel regions, thereby forming green organic emission layers, entirely depositing a blue organic emission material on the first substrate, thereby forming a blue organic emission layer, and sequentially forming a second related layer and a second electrode on the first substrate.