Organic Light Emitting Display Cathode Contact Structure
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Solution Overview
Problem
The manufacturing of organic light emitting display devices with top emission structures faces challenges due to increased resistance in the counter electrode, leading to voltage drops and higher manufacturing costs and complexity, particularly in the photo-lithography process for mask preparation and pattern transfer.
Innovation Solution
The solution involves an organic light emitting display device with a substrate, thin film transistor, and a cathode contact part comprising a first contact layer doped with ion impurities, a second contact layer made of the same material as the source and drain electrodes, and a counter electrode, which reduces resistance and simplifies the manufacturing process by eliminating the need for additional mask processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the counter electrode thickness is reduced to maintain top emission structure, then the aperture ratio is improved, but the resistance increases causing voltage drop
Solution Approach 1:
The counter electrode is segmented into multiple layers (first counter electrode layer and second counter electrode layer) with different materials and functions. The first layer provides low resistance while the second layer maintains transparency, resolving the contradiction between reducing thickness for aperture ratio and maintaining electrical conductivity.
Solution Approach 2:
The counter electrode uses composite material structure combining different materials (such as metal layers and transparent conductive oxide layers) to achieve both low resistance and high transparency, simultaneously satisfying the requirements for aperture ratio and voltage stability.
2Manufacturing precision
If photo-lithography process with mask is used for pattern formation, then manufacturing precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The mask preparation step is extracted and eliminated from the manufacturing process. Instead of using photo-lithography with masks, the invention employs direct patterning methods where patterns are formed without requiring separate mask fabrication and alignment steps, thereby reducing manufacturing complexity while maintaining precision.
Solution Approach 2:
The invention uses self-aligned patterning where previously formed structures serve as alignment references for subsequent layers, eliminating the need for external masks. This copying approach maintains manufacturing precision while significantly reducing process complexity and cost.
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 configuration effectively reduces voltage drops in the counter electrode while simplifying the manufacturing process, lowering costs, and maintaining a high aperture ratio for the top emission type organic light emitting display device.
Implementation Method 1
a first contact layer at a same layer as the active layer and being doped with ion impurities
Data Source
AI summary
An organic light emitting display device includes: a substrate; a thin film transistor (TFT) on the substrate and including an active layer, a gate electrode, a source electrode, and a drain electrode; an organic light emitting device including a pixel electrode that contacts at least one of the source electrode or the drain electrode of the TFT, an interlayer including a light emitting layer, and a counter electrode facing the pixel electrode, the pixel electrode, the interlayer, and the counter electrode being stacked; and a cathode contact part including a first contact layer and a second contact layer, the first contact layer being at a same layer as the active layer and being doped with ion impurities, the second contact layer including a same material as the source electrode and the drain electrode and coupling the first contact layer and the counter electrode to each other.