OLED Array Substrate Metal Lines Reduce Cathode Resistivity
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Solution Overview
Problem
Current OLED display devices face challenges with high resistivity in transparent cathodes, leading to performance issues and increased complexity and cost in fabrication due to the need for patterned metal layers and ITO contact methods.
Innovation Solution
An OLED array substrate design featuring a thin film transistor (TFT) with a first electrode, an organic material functional layer, and a transparent second electrode, along with a plurality of metal lines arranged between the base plate and the first electrode, which are connected in parallel to reduce resistivity and simplify the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a patterned metal layer is formed on a package substrate with an ITO layer to contact the metal layer and improve cathode resistivity, then the cathode resistivity is improved, but the fabricating process becomes complicated and cost increases
Solution Approach 1:
The invention divides the cathode structure into two functional parts: the ITO layer that contacts the OLED array substrate and the patterned metal layer that contacts the package substrate. This segmentation allows each layer to perform its optimal function while simplifying the overall fabrication process compared to forming multiple contact layers.
Solution Approach 2:
The invention uses a patterned metal layer as a conductive copy or alternative contact path that parallels the ITO contact function. This metal layer copy provides low-resistivity conduction while being formed through standard photolithography processes, avoiding complex multi-layer contact formation.
2Reliability
If a patterned metal layer and ITO contact method are used to improve cathode resistivity, then the resistivity is reduced, but productivity decreases due to increased process complexity
Solution Approach 1:
The invention merges the contact function with the existing ITO and metal layer structure already present in the OLED device. By utilizing the ITO layer's natural extension and combining it with a patterned metal layer formed in the same photolithography step, the solution achieves low resistivity without adding separate contact formation processes.
Solution Approach 2:
The patterned metal layer serves multiple functions: it provides low-resistivity electrical contact, acts as a structural support layer, and can be formed using the same photolithography process as other device patterns. This multi-functionality improves productivity by reducing the number of dedicated process steps.
3Illumination intensity
If transparent ITO with high resistivity is used for the cathode, then light can be emitted through the electrode, but voltage drop occurs and performance is adversely affected
Solution Approach 1:
The invention creates a composite cathode contact structure combining ITO (transparent but high resistivity) with a patterned metal layer (opaque but low resistivity). The ITO layer maintains light transmission while the metal layer provides low-resistivity conduction paths, achieving both optical and electrical performance requirements.
Solution Approach 2:
The patterned metal layer is strategically positioned in specific regions where high current density and voltage stability are critical, while the ITO layer maintains light emission in the display area. This local differentiation of material properties optimizes both electrical performance and optical function.
Data Source
AI summary
Embodiments provide an OLED array substrate, a method for fabricating the same, and a display device. The present invention relates to the field of display technology, can decrease resistivity of an electrode, and avoid increase in patterning process. The OLED array substrate comprises an effective pixel display area and a peripheral wiring area. The effective pixel display area comprises a TFT which is arranged on a base plate. The array substrate further comprises a plurality of conductors which are arranged between the base plate and the first electrode; wherein, in the peripheral wiring area, the plurality of conductors are connected with the second electrode.