OLED Pixel Structure With Maskless Cathode Confinement
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Solution Overview
Problem
The aperture ratio of OLED pixel structures is insufficient due to the use of expensive Fine Metal Mask (FMM) evaporation methods, which limit the effective light-emitting area, and the pixel drive circuit occupies a large spatial footprint.
Innovation Solution
A pixel structure is designed with overlapping metal and insulation structures to confine electroluminescent layer and pixel cathode film-forming regions without a mask, allowing the pixel anode to form capacitive structures, reducing the need for additional spatial capacitors and minimizing the pixel drive circuit's footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If FMM evaporation method is used to fabricate OLED pixel structure, then the pixel structure can be manufactured with precise pattern, but the aperture ratio is reduced due to mask bridge area and manufacturing cost increases
Solution Approach 1:
The patent extracts and removes the mask component from the fabrication process. Instead of using FMM evaporation method with physical masks, the invention employs a self-aligned fabrication process where the pixel definition layer and metal structures are formed through sequential deposition and patterning steps that eliminate the need for expensive masks, thereby removing the source of aperture ratio reduction while maintaining manufacturing precision
Solution Approach 2:
The patent transitions from a two-dimensional mask-based patterning approach to a three-dimensional self-aligned structure formation. By creating overlapping metal and insulation structures that extend in multiple layers and dimensions, the invention achieves precise pattern definition without relying on mask openings, thus eliminating the bridge area problem and increasing aperture ratio
2Manufacturing precision
If FMM evaporation method is used to fabricate OLED pixel structure, then the pixel structure can be manufactured with precise pattern, but the manufacturing cost increases due to expensive mask
Solution Approach 1:
The patent extracts and removes the mask component from the fabrication process. Instead of using FMM evaporation method with physical masks, the invention employs a self-aligned fabrication process where the pixel definition layer and metal structures are formed through sequential deposition and patterning steps that eliminate the need for expensive masks, thereby removing the source of cost increase while maintaining manufacturing precision
Solution Approach 2:
The patent replaces expensive, reusable masks with inexpensive, temporary patterning structures that are formed during the fabrication process and then removed or integrated into the final device. The pixel definition layer and metal structures serve as temporary patterning elements that define the pixel regions without requiring costly masks, significantly reducing manufacturing cost
3Ease of operation
If traditional pixel structure is used, then the pixel drive circuit can be laid out, but the spatial footprint occupied by the pixel drive circuit is relatively large
Solution Approach 1:
The patent merges the pixel electrode structures with the drive circuit elements. The first and second metal structures serve dual purposes: they form the pixel electrodes for light emission and simultaneously function as one of the capacitive structures for charge storage. This integration eliminates the need for separate dedicated capacitor areas, reducing the overall spatial footprint of the pixel drive circuit
Solution Approach 2:
The patent implements multi-functionality where the metal structures serve multiple functions: electrical connection, electrode formation, and capacitive energy storage. The first metal structure and second metal structure not only act as pixel electrodes but also form capacitive structures with the pixel anode, thereby performing both driving and storage functions within the same structural elements, minimizing the required spatial area
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 design reduces manufacturing costs, increases the light-emitting area, and enhances the aperture ratio of the pixel structure by eliminating the need for a mask and optimizing the layout of the pixel drive circuit.
Implementation Method 1
an electroluminescent layer covering a portion of the first pixel definition layer, a portion of the pixel anode and a portion of the second pixel definition layer
Data Source
AI summary
A pixel structure which includes: a drive substrate; a first pixel definition layer, a pixel anode and a second pixel definition layer sequentially arranged on the drive substrate; a first metal structure arranged on the first pixel definition layer and a second metal structure arranged on the second pixel definition layer, where the pixel anode extends to a corresponding position below the second metal structure in the second pixel definition layer; a first insulation structure arranged on the first metal structure and a second insulation structure arranged on the second metal structure; an electroluminescent layer covering a portion of the first pixel definition layer, a portion of the pixel anode and a portion of the second pixel definition layer; and a pixel cathode covering the electroluminescent layer, where two ends of the pixel cathode are respectively connected to the first metal structure and the second metal structure.