Oxide Semiconductor Transparent Electrodes for Bottom Emission Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing electroluminescent (EL) substrates require a large number of photomasks and processes, leading to high production costs and low yield, and are unable to achieve a high aperture ratio while maintaining sufficient electric charge, especially for bottom emission type substrates.
Innovation Solution
The use of an oxide semiconductor layer on a gate insulating film, where the semiconductor layer is patterned to form a transistor, electroluminescent element, and capacitor section, with a protective layer having openings to expose the electrodes, allowing for reduction to form transparent electrodes that eliminate the need for ITO layers and reduce the number of photomasks required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography methods with multiple photomasks are used to form transistor, electroluminescent element, and capacitor section, then each component can be formed with precise patterning, but the number of photomasks and processes increases significantly, leading to high production costs and low yield
Solution Approach 1:
The patent merges the formation of transistor semiconductor layer, electroluminescent element lower electrode, and capacitor upper electrode into a single oxide semiconductor layer that is patterned using one photomask. This combining approach reduces the number of photomasks from multiple to one, simplifying the manufacturing process while maintaining the ability to form all three components with appropriate patterns.
Solution Approach 2:
The oxide semiconductor layer serves multiple functions simultaneously: it acts as the semiconductor layer for the transistor, the lower electrode for the electroluminescent element, and the upper electrode for the capacitor section. This multi-functionality eliminates the need for separate layers and photomasks for each component, reducing process complexity.
2Illumination intensity
If ITO layers are used to form transparent electrodes for bottom emission type substrates, then good transparency and electrical conductivity are achieved, but the aperture ratio is reduced and additional manufacturing steps are required
Solution Approach 1:
The patent changes the material parameter from ITO (indium tin oxide) to oxide semiconductor material that can be reduced to form transparent conductive electrodes. This parameter change allows the electrode to be formed from the same oxide semiconductor layer used for other components, eliminating the need for separate ITO layers and increasing the aperture ratio while maintaining transparency and conductivity.
Solution Approach 2:
The patent extracts the transparent electrode function from the separate ITO layer and integrates it into the oxide semiconductor layer itself. By reducing the oxide semiconductor layer, the transparent conductive electrode is formed in-situ, eliminating the need for additional ITO deposition steps and increasing the effective aperture area.
3Adaptability or versatility
If multiple separate layers are used for transistor semiconductor, electroluminescent lower electrode, and capacitor upper electrode, then each component can be optimized independently, but the number of manufacturing processes and photomasks increases
Solution Approach 1:
The patent combines three separate functional layers (transistor semiconductor, electroluminescent lower electrode, capacitor upper electrode) into a single oxide semiconductor layer. This merging maintains the ability to optimize each component's properties through selective processing and pattern design, while dramatically improving production efficiency by reducing the number of deposition and patterning steps.
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 approach reduces the number of photomasks and processes needed, improves the aperture ratio, and enables the production of electroluminescent substrates with enhanced electric charge retention and transparency, specifically for bottom emission types without requiring ITO layers.
Implementation Method 1
each of the lower part electrode and the upper part electrode being a reduction electrode which has been made by reducing the oxide semiconductor layer provided on the gate insulating film
Data Source
AI summary
The EL substrate includes semiconductor layers of TFTs, a pixel electrode, and an upper part electrode of a Cs section which are provided on a gate insulating film. The semiconductor layers are covered with a protective film which has openings via which the pixel electrode and the upper part electrode are exposed. The semiconductor layers are an oxide semiconductor layer, and the pixel electrode and the upper part electrode are reduction electrodes of the oxide semiconductor layer.