Auxiliary Electrode for OLED Voltage Drop Reduction
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Solution Overview
Problem
Organic light emitting display devices with top emission type organic light emitting elements face voltage drop issues due to the high electrical resistance of thin cathodes, leading to non-uniform luminance, especially as the size of the display increases.
Innovation Solution
Incorporating an auxiliary electrode between pixel areas with a conductive partition and supplemental conductive layer to reduce voltage drop by ensuring electrical connection between the cathode and the auxiliary electrode, which is formed using conductive materials with high step coverage to compensate for the resistivity of the cathode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode is made thin to achieve sufficient light transmittance, then light transmittance is improved, but electrical resistance increases causing voltage drop
Solution Approach 1:
An auxiliary electrode is introduced as an intermediary component between the cathode and the organic light emitting layer. This auxiliary electrode serves as a mediator that provides an additional electrical conduction path, compensating for the high resistance of the thin cathode while maintaining light transmittance properties.
Solution Approach 2:
The auxiliary electrode is positioned in a different spatial dimension - specifically, it is formed in the intermediate area between pixel areas rather than directly in the pixel emission area. This dimensional separation allows the auxiliary electrode to provide electrical compensation without interfering with the light emission and transmittance functions of the cathode in the pixel regions.
2Area of stationary object
If the display device size is increased, then display area is improved, but voltage drop phenomenon intensifies
Solution Approach 1:
The display device is segmented into multiple pixel areas with intermediate areas between them. The auxiliary electrode is specifically placed in these intermediate areas, creating a segmented electrical compensation structure that can be scaled to larger display areas without intensifying voltage drop, as each segment independently manages its electrical characteristics.
3Reliability
If a conductive layer is formed to reduce voltage drop, then electrical conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The auxiliary electrode with supplemental conductive layer is formed only in the intermediate areas between pixel areas, not across the entire display area. This localized approach provides electrical compensation where needed while minimizing the addition of complex manufacturing steps compared to a full-area conductive layer.
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
The solution effectively reduces voltage drop and maintains uniform luminance across the display by ensuring efficient electrical connection and conductivity, addressing the limitations of thin cathodes in large-sized organic light emitting display devices.
Implementation Method 1
The decrease in thickness of the cathode, however, increases the surface electrical resistance. The increased electrical resistance, in turn, causes voltage drop (i.e., IR drop) in some parts of the organic light emitting display device
Implementation Method 2
formed using conductive materials with high step coverage to compensate for the resistivity of the cathode
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
Provided are an organic light emitting display device and a method for manufacturing the same. The organic light emitting display device comprises at least a first pixel area and a second pixel area. A partition is disposed between the first pixel area and the second pixel area. An auxiliary electrode is disposed between the first pixel area and the second pixel area and over the partition. Additionally, a first conductive element is disposed over the first pixel area, the second pixel area, and the auxiliary electrode and the first conductive element is electrically connected to the auxiliary electrode.