OLED Pixel Definition Layers with Varying Heights for Color Reproducibility
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Solution Overview
Problem
Existing organic light emitting display manufacturing processes face challenges in achieving uniformity of organic light emitting layer thickness across pixels, leading to variations in light emission colors and reduced color reproducibility, which complicates the process and increases manufacturing costs.
Innovation Solution
The use of pixel definition layers with varying heights to control the thickness of organic light emitting devices, allowing for distinct thicknesses of red, green, and blue light emitting layers, achieved through a method involving inkjet or nozzle printing of organic material, simplifying the spraying condition and concentration requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the organic light emitting layer is adjusted to improve color reproducibility, then color accuracy improves, but manufacturing complexity and process control difficulty increase
Solution Approach 1:
The pixel definition layer is formed with predetermined varying thicknesses corresponding to different color pixels (red, green, blue) before the organic light emitting layer is deposited. This preliminary structuring allows the organic layer to naturally conform to the desired thickness profile during a single deposition process, eliminating the need for separate thickness control steps for each pixel type and simplifying the overall manufacturing process.
Solution Approach 2:
The pixel definition layer serves as an intermediary structure that translates the desired final thickness profile of the organic light emitting layer into a manufacturable form. By pre-forming this definition layer with the appropriate thickness variations, the system uses this intermediate structure to guide the subsequent deposition process, achieving precise thickness control without complex real-time monitoring or adjustment mechanisms.
2Manufacturing precision
If different concentrations of organic material are used to form layers of different thicknesses, then thickness uniformity improves, but material cost and process complexity increase
Solution Approach 1:
Instead of varying the concentration of organic material across different pixels, the invention uses a uniform concentration approach where the pixel definition layer's varying thickness locally determines the final organic layer thickness. Each region receives the same material concentration, but the local thickness requirement is satisfied by the pre-formed pixel definition layer structure, simplifying material preparation and dispensing processes.
Solution Approach 2:
The pixel definition layer is pre-formed with the exact thickness profile needed for each pixel type before organic material deposition. This preliminary action eliminates the need to prepare and manage multiple organic material solutions with different concentrations, reducing material handling complexity and potential sources of error while maintaining precise thickness control.
3Manufacturing precision
If multiple printing passes are used to form the organic light emitting layer, then thickness control improves, but manufacturing time and productivity decrease
Solution Approach 1:
The pixel definition layer is pre-formed with the desired thickness profile before organic material deposition. This preliminary structuring allows a single printing pass to achieve the required thickness variations, as the organic material simply conforms to the pre-established template. This eliminates the need for multiple sequential printing passes, directly improving manufacturing throughput while maintaining precise thickness control.
Solution Approach 2:
The pixel definition layer acts as a physical template or copy of the desired final structure. By depositing organic material that conforms to this template in a single pass, the invention reproduces the target thickness profile efficiently without requiring iterative printing processes, thereby enhancing productivity while preserving manufacturing precision.
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 the uniformity of organic light emitting devices, improves color reproducibility, and simplifies the manufacturing process by controlling the thickness of each light emitting layer, thereby increasing light efficiency and reducing manufacturing complexity and costs.
Implementation Method 1
Holes and electrons are injected into the organic emitting layer through the anode electrode and the cathode electrode, and are recombined in the organic light emitting layer to generate excitons (electron-hole pairs). The excitons emit energy, which is discharged when an excited state returns to a ground state, as light.
Implementation Method 2
The organic light emitting layer is formed in various ways, such as an inkjet printing process, a nozzle printing process, etc.
Data Source
AI summary
An organic light emitting display is disclosed. In one aspect, the display includes a substrate, thin film transistors disposed on the substrate, first, second, and third pixel definition layers disposed on the thin film transistors, respectively having openings, and respectively having first, second, and third heights different from each other, and first, second, and third organic light emitting devices disposed in the openings of the first, second, and third pixel definition layers and connected to the thin film transistors, respectively. The first, second, and third pixel definition layers are spaced apart from each other, the first, second, and third organic light emitting devices have different thicknesses from each other, and the first, second, and third organic light emitting devices have thicknesses respectively corresponding to the first, second, and third heights of the first, second, and third pixel definition layers.