Auxiliary Common Electrode Layout for Large-Area Display Voltage Drop
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Solution Overview
Problem
As display screens become larger, the resistance of the common electrode increases, leading to a voltage drop phenomenon that deteriorates display quality in display devices.
Innovation Solution
The display device incorporates a thin-film transistor, a source/drain electrode, and an auxiliary electrode formed as a same layer with conductive layers, along with a capping layer and a common electrode layer, featuring an undercut shape and conductive materials to reduce voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the common electrode size is increased to cover larger display screens, then the display area is improved, but the voltage drop phenomenon worsens due to increased resistance
Solution Approach 1:
The common electrode is divided into multiple separate common electrode patterns arranged in parallel, with auxiliary electrodes connecting them. This segmentation reduces the resistance between different regions of the common electrode, thereby minimizing voltage drop across the entire display screen while maintaining the required coverage area.
Solution Approach 2:
Auxiliary electrodes are introduced as intermediary conductive elements between the main common electrode patterns. These auxiliary electrodes act as mediators that provide additional conductive pathways, reducing the overall resistance and voltage drop in the common electrode structure without requiring further expansion of the main electrode area.
2Reliability
If the common electrode resistance is reduced to minimize voltage drop, then the voltage stability is improved, but the device complexity increases due to additional auxiliary electrodes and capping layers
Solution Approach 1:
The auxiliary electrodes are formed using the same conductive layer deposition process as the main common electrode, merging the fabrication steps. The capping layer is also deposited in the same process step, combining multiple functions (protection, conductivity enhancement, and structural support) into a single integrated structure, thereby reducing overall manufacturing complexity despite the additional functional elements.
Solution Approach 2:
The capping layer serves multiple functions simultaneously: it protects the auxiliary electrodes from oxidation, maintains electrical conductivity, and provides structural support for subsequent layers. This multi-functionality reduces the need for separate protective and conductive layers, thereby reducing device complexity while achieving voltage stability.
3Reliability
If the capping layer is added to cover the auxiliary electrode, then the oxidation prevention is improved, but the manufacturing steps increase
Solution Approach 1:
The capping layer is deposited immediately after forming the auxiliary electrodes, before any subsequent processing steps that could expose the auxiliary electrodes to oxidation. This preliminary protective action ensures oxidation resistance is established early in the manufacturing process. The capping layer is also deposited in the same process step as the auxiliary electrode formation, minimizing additional manufacturing steps.
Data Source
AI summary
A display device includes a thin-film transistor, a source/drain electrode and an auxiliary electrode including a first conductive layer and a second conductive layer disposed on the first conductive layer, a via insulating layer having a first opening exposing the auxiliary electrode, a capping layer covering a portion of the auxiliary electrode and a light emitting material layer and a common electrode layer sequentially stacked on the via insulating layer and the capping layer, wherein the source/drain electrode is electrically connected to the thin-film transistor through a contact hole penetrating the interlayer insulating layer, the auxiliary electrode has an undercut, and the capping layer includes a first capping layer covering side surfaces of the first conductive layer of the auxiliary electrode and a second capping layer separated from the first capping layer and disposed on the second conductive layer of the auxiliary electrode.