Misaligned Substrates in OLED Devices for Aperture Ratio
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Solution Overview
Problem
The existing organic electro-luminescence devices face limitations in yield and aperture ratio, particularly in the bottom emission type, due to the alignment of substrates and the restriction on material selection for the cathode in top emission types, which affects luminous efficiency and production efficiency.
Innovation Solution
The substrates are misaligned by a predetermined distance, allowing conductive spacers to connect and enabling the use of various materials for the electrodes, thereby reducing design constraints on TFTs and improving aperture ratio and production management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If substrates are accurately aligned in bottom emission type devices, then manufacturing precision is improved, but aperture ratio is reduced due to seal pattern constraints
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the second substrate relative to the first substrate in a controlled manner. The substrates are shifted by a predetermined distance (e.g., 0.5-2 mm) in a specific direction, breaking the traditional symmetric alignment. This asymmetric positioning allows the aperture opening to be positioned optimally within the pixel area, increasing the aperture ratio while maintaining manufacturing feasibility through the seal pattern's flexible configuration.
2Device complexity
If cathode material selection is restricted in top emission type devices, then manufacturing complexity is reduced, but luminous efficiency deteriorates
Solution Approach 1:
The patent changes the material parameter of the cathode electrode by selecting materials with low work function (such as Al, Ag, Mo, or their alloys) specifically optimized for top emission devices. This parameter change enables efficient electron injection into the organic electro-luminescence layer, significantly improving luminous efficiency. The manufacturing complexity remains manageable through standardized deposition processes, balancing material optimization with process feasibility.
3Reliability
If conductive spacers are used to connect substrates, then electrical connection is improved, but design constraints on TFTs increase due to alignment requirements
Solution Approach 1:
The patent applies preliminary action by pre-positioning the conductive spacers on the first substrate at predetermined locations before substrate attachment. The spacers are formed with specific dimensions and positions that anticipate the misalignment of the second substrate. This preliminary positioning ensures that after misalignment, the spacers still make reliable electrical contact between the TFT and the electrode on the second substrate, reducing design constraints on the TFT structure.
Data Source
AI summary
An organic electro-luminescence device is provided. First and second substrates are arranged spaced apart from each other by a predetermined distance and sub-pixels are defined in the substrates. An array element has at least one thin film transistor (TFT) formed on an inner surface of the first substrate in sub-pixel unit. A conductive spacer is electrically connected to a drive TFT of the array element. A first electrode for an organic electro-luminescence diode is disposed on an inner surface of the second substrate. An organic electro-luminescence layer and a second electrode for the organic electro-luminescence diode are sequentially formed on the first electrode in sub-pixel unit. The first substrate and the second substrate are misaligned by a predetermined position and attached to each other, such that the conductive spacer is in contact with a conductive spacer contact region provided on the second electrode.