Cascaded OLEDs with Middle Electrodes for Short Tolerance
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Solution Overview
Problem
Existing OLED-based displays face challenges with increased probability of electrical shorts as the area increases, leading to unacceptable image degradation, and current architectures for fault tolerance and large-area manufacturing are complex and costly.
Innovation Solution
The development of cascaded light emitting devices with a mixed conductor structure that eliminates the need for patterning of electroluminescent layers, allowing for alternating current driving and increased tolerance to shorts, featuring a base and top electrode with middle electrodes between electroluminescent layers, and a split electrode structure with high resistance between electrode portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area of an OLED increases, then the display coverage and visibility are improved, but the probability of electrical shorts increases
Solution Approach 1:
The OLED panel is divided into multiple independently addressable pixel elements, each with its own switching mechanism. This segmentation allows the panel to be divided into functional units that can operate independently, reducing the impact of shorts on the overall display
Solution Approach 2:
An active matrix structure with switching transistors is introduced as an intermediary between the row and column electrodes and the OLED elements. This intermediary enables precise control of current flow to individual pixels, allowing shorts to be isolated and preventing them from affecting entire rows or columns
2Device complexity
If a passive matrix architecture is used, then the manufacturing complexity is reduced, but the image quality deteriorates due to short-induced pixel failures
Solution Approach 1:
The display is segmented into individually controllable pixel elements with dedicated switching transistors, enabling precise addressing of each pixel. This segmentation allows for localized control and isolation of defects, maintaining image quality even in the presence of shorts
Solution Approach 2:
The active matrix architecture introduces dynamic control through switching transistors that can be programmed to control current flow timing and magnitude. This dynamic control enables sophisticated pixel addressing schemes that can compensate for or isolate short circuit conditions
3Manufacturing precision
If an active matrix architecture is used, then the image quality is maintained, but the manufacturing cost and difficulty increase
Solution Approach 1:
The switching transistors in the active matrix serve multiple functions: they act as pixel switches, current regulators, and defect isolation mechanisms. This multi-functionality reduces the need for additional specialized components, simplifying the overall manufacturing process while maintaining image quality
Solution Approach 2:
The invention utilizes changes in electrical parameters (voltage levels, current timing) to control pixel activation and deactivation. By manipulating these parameters dynamically, the system achieves precise pixel control without requiring complex physical structures, reducing manufacturing complexity
4Reliability
If laser ablation is used to pattern the organic layer, then the fault tolerance is achieved, but the manufacturing complexity and time increase significantly
Solution Approach 1:
The invention replaces the mechanical laser ablation process with a chemical or self-organizing patterning mechanism. The organic layer is patterned through controlled deposition or self-assembly processes that occur during standard OLED fabrication, eliminating the need for post-deposition laser processing and significantly improving manufacturing throughput
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 solution simplifies manufacturing, enhances optical output, and provides increased resistance to manufacturing defects, allowing for high-yield, cost-effective production of large-area OLED panels with improved fault tolerance and efficient AC driving.
Implementation Method 1
The electroluminescent layers include a mixed conductor that luminesces with a peak wavelength
Data Source
AI summary
A cascaded light emitting device. The cascaded light emitting device includes: a base electrode formed of a base electrode material and electrically coupled to a base voltage lead; a top electrode layer formed of a top electrode material and electrically coupled to a top voltage lead; a number of electroluminescent layers arranged between and electrically coupled to the base electrode and top electrode layer; and at least one middle electrode layer formed of a middle electrode material. Each of the middle electrodes is coupled between two juxtaposed electroluminescent layers. The electroluminescent layers include a mixed conductor that luminesces with a peak wavelength.