OLED Light Emitting Device with Segmented Electrodes for AC Driving
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Solution Overview
Problem
Existing solutions for delaying the aging of OLEDs in display panels, such as alternating the light emission of two OLEDs sharing common electrodes, cause shifts in the threshold voltage of the driving thin film transistor, leading to differences in brightness and affecting the display effect.
Innovation Solution
A light emitting device comprising a first and a second light emitting unit, where both units are alternately conducted and connected to AC power supplies, reducing the impact on the threshold voltage of the driving thin film transistor and improving the display effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If two OLEDs share common electrodes and alternate light emission is implemented using AC power supplies, then the aging of OLEDs is delayed and service life is extended, but the threshold voltage of the driving thin film transistor shifts causing brightness differences
Solution Approach 1:
The light emitting device is divided into a first light emitting unit and a second light emitting unit, each with independent electrode structures (first anode, first cathode, second anode, second cathode). This segmentation allows each unit to be driven independently by separate AC power supplies, preventing the threshold voltage shift problem that occurs with shared electrodes while enabling alternate light emission to extend overall service life.
2Manufacturing precision
If DC power supplies are used to drive OLEDs, then the threshold voltage of driving transistors remains stable, but the OLEDs age faster and service life is reduced
Solution Approach 1:
The patent employs AC power supplies to drive the first and second light emitting units in an alternating periodic manner. The first light emitting unit emits light during one half-cycle while the second unit is off, then they switch in the next half-cycle. This periodic action extends service life by allowing each OLED unit to rest during the other's operation, while the AC waveform itself prevents threshold voltage shift that would occur with continuous DC operation.
3Duration of action of stationary object
If AC power supplies are used for alternate light emission, then service life of OLEDs is extended, but brightness uniformity deteriorates due to threshold voltage shifts
Solution Approach 1:
By segmenting the electrode structures into independent first anode/first cathode and second anode/second cathode pairs, each light emitting unit can be driven by its own AC power supply. This eliminates the threshold voltage shift problem caused by shared electrodes, ensuring that both units maintain stable operating characteristics and produce uniform brightness during alternate light emission, while still extending service life through the alternating operation mode.
Data Source
AI summary
A light emitting device includes: a first light emitting unit and a second light emitting unit arranged beneath the first light emitting unit. The first light emitting unit and the second light emitting unit are alternately conducted. The first light emitting unit includes: a first cathode, a first electron transport layer, a first luminescent layer, a first hole transport layer, and a first anode arranged sequentially from bottom to top. The second light emitting unit includes: a second anode, a second hole transport layer, a second luminescent layer, a second electron transport layer, and a second cathode arranged sequentially from bottom to top. The first cathode, the first anode, the second cathode, and the second anode are all connected to AC power supplies, respectively.