Stacked OLED Mixed Region Charge Transport
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Solution Overview
Problem
Stacked OLED configurations face limited operational stability, which affects their performance and longevity in display applications despite achieving high electroluminescence efficiency.
Innovation Solution
Incorporating a mixed region with a mixture of materials having different electron and hole transport capacities, along with optional dopants, between luminescent regions in a stacked OLED configuration, where the materials can be independently selected from hole transport, electron transport, and bipolar transport materials, to enhance charge transport and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If stacked OLED configurations are used to achieve high electroluminescence efficiency, then brightness and efficiency are improved, but operational stability deteriorates
Solution Approach 1:
The patent introduces a mixed region with specific local composition between luminescent regions, where materials are selectively combined to optimize charge transport properties in critical areas without altering the overall stacked structure. This local modification improves operational stability while preserving the high efficiency benefits of the stacked configuration.
Solution Approach 2:
The patent employs composite materials in the mixed region, combining multiple organic materials with different electron and hole transport capacities. This composite approach creates a balanced charge transport environment that enhances device stability while maintaining high electroluminescence efficiency in the stacked OLED structure.
2Adaptability or versatility
If intermediate electrodes are added between luminescent regions to enable stacked configuration, then device functionality is improved, but device complexity increases
Solution Approach 1:
The intermediate electrodes in the stacked OLED structure are designed to perform multiple functions simultaneously: serving as charge injection contacts, charge transport pathways, and structural support between luminescent regions. This multi-functionality reduces the need for additional separate components, thereby managing complexity while enhancing device functionality.
Solution Approach 2:
The stacked OLED is divided into discrete functional modules (luminescent regions separated by intermediate electrodes), allowing independent optimization of each segment. This segmentation enables complex functionality to be achieved through modular design, where each intermediate electrode can be tailored for specific charge transport requirements without redesigning the entire device.
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 improves the operational stability of stacked OLEDs while maintaining high electroluminescence efficiency, as demonstrated by comparative examples showing comparable stability to non-stacked OLEDs with increased brightness and efficiency.
Implementation Method 1
at least one of the plurality of luminescent regions comprises a mixed region, the mixed region comprising a mixture of at least two materials having different electron and hole transport capacities... and wherein the mixed region there is at least one electroluminescent material capable of emitting light
Data Source
AI summary
A stacked OLED device comprises a plurality of individual OLEDs in a vertical stacked arrangement separated by intermediate electrodes, wherein at least one of the individual OLEDs includes a light emitting region or zone comprising a mixed region; the mixed region comprising a mixture of a hole transport material, an electron transport material, and optionally a dopant.