OLED Upper Transparent Electrode Wiring Resistance Reduction
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Solution Overview
Problem
In organic light emitting display devices, the use of a highly-resistive upper transparent electrode leads to uneven voltage application across the display panel due to wiring resistance, resulting in luminance inconsistencies and reduced mass productivity due to the need for precision masks in patterning organic layers.
Innovation Solution
A method where the upper transparent electrode is connected electrically to a current supply line within the driving layer, allowing the organic layers to be formed over the entire display region without precision masks, thereby reducing wiring resistance and luminance unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a highly-resistive transparent conductive film is used for the upper transparent electrode, then the transparency and light emission quality are improved, but the wiring resistance increases causing uneven voltage distribution and luminance inconsistency across the display panel
Solution Approach 1:
The upper transparent electrode is divided into multiple segments corresponding to different pixel regions. Each segment is independently connected to current supply lines, allowing separate voltage control and compensation for wiring resistance effects across different areas of the display panel.
Solution Approach 2:
Different regions of the upper transparent electrode are assigned different electrical connection characteristics. Peripheral regions are connected with lower resistance paths compared to central regions, compensating for the voltage drop that occurs in highly-resistive materials and achieving uniform voltage distribution across the entire panel.
2Manufacturing precision
If precision masks are used for patterning organic layers to achieve pixel-level precision, then the manufacturing precision is improved, but the productivity decreases due to frequent mask exchange and complex processing
Solution Approach 1:
The light emitting layer is extracted and patterned separately from the transport layers. The transport layers are formed over the entire display region without patterning, while the light emitting layer is selectively formed only in pixel regions using simple masks, eliminating the need for precision masks and complex multi-step patterning processes.
Solution Approach 2:
Instead of patterning all organic layers with precision masks, the invention inverts the approach by forming transport layers uniformly across the entire surface and only patterning the light emitting layer where needed. This reverses the conventional sequence and simplifies the masking requirements significantly.
Data Source
AI summary
The present invention provides an organic light emitting device in which an upper transparent electrode 10 of an organic light emitting device 2 is connected electrically at a contact hole portion 122 to a current supply line 121 disposed in the same layer as that of and extending in parallel with a gate line 106. That is, a hole transport layer 5 and an electron transport layer 9 of the organic light emitting device 2 are formed over the entire display region, and then a contact hole portion 122 is removed to electrically connect the current supply line 121 and the upper transparent electrode 10, thereby decreasing unevenness of luminance due to wiring resistance of the upper transparent electrode.