OLED Display Common Electrode Resistance Reduction
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Solution Overview
Problem
The manufacturing of large-sized top emission type OLED displays is hindered by high resistance in the current transparent common electrode, which affects the application of a common voltage effectively.
Innovation Solution
A display device structure incorporating a thin film transistor, a pixel electrode, an organic layer, a conductive layer, a transparent electrode layer applied with a common voltage, and a second insulating substrate, where the conductive layer can include conductive polymers or particles like Ag or Ni, and the common electrode is made of materials like Mg and Ag, with a thickness of 50 Å to 200 Å, allowing effective voltage application through a transparent electrode layer made of ITO or IZO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin metal layer deposition method (e.g., sputtering) using ITO or IZO is used to create a transparent common electrode, then the electrode transparency is improved, but the resistance becomes too high for large-sized displays
Solution Approach 1:
The patent applies a composite structure consisting of a transparent electrode layer (ITO or IZO) and a conductive polymer layer. This composite material combination allows the transparent electrode to maintain its transparency while the conductive polymer layer provides additional conductivity to reduce overall resistance, solving the contradiction between transparency and resistance in large-sized display applications
Solution Approach 2:
The patent changes the electrical parameters of the common electrode by introducing a conductive polymer layer with different conductivity characteristics. This parameter change enables the electrode to achieve both transparency (from the ITO/IZO layer) and low resistance (from the conductive polymer), resolving the contradiction for large display applications
2Area of moving object
If the common electrode is made transparent for top emission type OLED, then the aperture ratio is improved, but the resistance increases making voltage application ineffective
Solution Approach 1:
The patent uses a composite structure of transparent electrode material (ITO/IZO) and conductive polymer to achieve both high aperture ratio (through transparency) and effective voltage application (through reduced resistance provided by the conductive polymer layer)
Solution Approach 2:
The conductive polymer acts as an intermediary layer between the transparent electrode and the organic light-emitting layer, providing the necessary conductivity for effective voltage application while allowing the transparent electrode to maintain its transparency and high aperture ratio
Data Source
AI summary
A display device, and method for making the same, comprising a thin film transistor formed on a first insulating substrate, a pixel electrode electrically connected to the thin film transistor, an organic layer formed on the pixel electrode, a common electrode formed on the organic layer, a conductive layer formed on the common electrode, a transparent electrode layer formed on the conductive layer, the transparent electrode being applied with a common voltage, and a second insulating substrate located on the transparent electrode layer. Thus, the present invention provides a display device to which common voltage is applied effectively.