Top Emitting OLED Transparent Anode Inversion
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Solution Overview
Problem
Existing OLED display devices face challenges with low transmittance and aperture ratio, particularly in top emitting modes, due to restricted cathode material choices and light emission paths that pass through areas with thin film transistors, limiting their application in large-scale high-resolution displays.
Innovation Solution
A top emitting OLED display device design featuring a transparent anode on a second substrate with partition walls and transmission holes, and a metal cathode on the organic layer and partition walls, where the cathode is electrically connected to the thin film transistor's drain metal layer through a concave area in the passivation layer, allowing for high transmittance and aperture ratio without material selection constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a top emitting OLED display device is designed with a metal cathode on the organic layer, then the aperture ratio is improved, but the transmittance is restricted due to material selection constraints
Solution Approach 1:
The patent inverts the conventional OLED structure by placing the transparent anode on the second substrate instead of the first substrate, and positioning the metal cathode on the organic layer on the second substrate. This inversion allows light to emit through the transparent anode rather than being blocked by the metal cathode, thereby achieving high transmittance while maintaining high aperture ratio.
2Adaptability or versatility
If the cathode material is selected from calcium, aluminum, or magnesium, then the manufacturing flexibility is improved, but the light transmittance is restricted
Solution Approach 1:
By inverting the OLED structure and positioning the transparent anode on the light emission path (second substrate), the patent enables the use of metal cathode materials like calcium, aluminum, or magnesium without compromising transmittance. The transparent anode becomes the primary light transmission component, while the metal cathode serves its electrical function without blocking light.
3Device complexity
If light emission passes through the bottom where thin film transistors are formed, then the device structure is simplified, but the aperture ratio is decreased
Solution Approach 1:
The patent inverts the light emission direction by placing the transparent anode on the second substrate and emitting light upward through the transparent anode rather than downward through the thin film transistor layer. This eliminates the need for light to pass through the TFT area, thereby increasing the aperture ratio while maintaining structural simplicity.
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 enables a top emitting OLED display device with high transmittance and aperture ratio, improving manufacturing yield and productivity by allowing for the selection of cathode materials like calcium, aluminum, or magnesium, and facilitating efficient light emission through the transparent anode.
Implementation Method 1
The electrons and holes are combined to generate excited electron-hole pairs, and the excited electron-hole pairs are converted from an excited state to a ground state for achieving illumination.
Implementation Method 2
a transparent anode located on an inner surface of the second substrate
Data Source
AI summary
A method for manufacturing an OLED display device that includes pixel areas is provided. A first and a second substrates are provided. TFTs are arranged on the first substrate. A passivation layer is formed on the TFTs such that the passivation layer includes a concave area formed in a surface thereof to expose a part of a drain of each of the TFTs. A transparent anode is formed on the second substrate. Partition walls are arranged on the transparent anode to defined therebetween transmission holes respectively corresponding to the pixel areas. An organic layer is formed on the transparent anode and located in the transmission holes. A metal cathode is formed on the organic layer and the partition walls such that the metal cathode is receivable into the concave area and electrically engageable with the exposed part of the drain of each of the TFTs.