Tandem Light Emitting Device with Charge Generation Element
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Solution Overview
Problem
Conventional light emitting devices with single light emitting elements between electrodes face limitations in luminance efficiency and electroluminescent lifetime, and suffer from current short/leakage paths.
Innovation Solution
A light emitting device with a stacked arrangement of two or more light emitting elements, where a charge generation element comprising an inorganic n-type semiconductor material and a hole injection material is placed between adjacent light emitting elements, facilitating electron and hole injection, thereby enhancing luminance efficiency and reducing current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light emitting element is used between electrodes, then the device structure is simple, but the luminance efficiency and electroluminescent lifetime are limited and current short/leakage paths occur
Solution Approach 1:
The device is divided into multiple light emitting elements arranged in a stacked configuration between the electrodes, with charge generation elements positioned between adjacent light emitting elements. This segmentation allows each element to contribute to overall light output while the charge generation elements independently manage charge injection, thereby improving luminance efficiency and device reliability without requiring a completely new device architecture
2Reliability
If a stacked arrangement of multiple light emitting elements is used, then luminance efficiency and electroluminescent lifetime are improved, but the device complexity increases
Solution Approach 1:
Charge generation elements are introduced as intermediary components between adjacent light emitting elements in the stacked arrangement. These intermediaries facilitate efficient charge transfer and injection between elements, ensuring high luminance efficiency and stable operation while maintaining a manageable device structure through modular design
3Ease of manufacture
If conventional single element structure is used, then manufacturing is simpler, but current short/leakage paths reduce device performance
Solution Approach 1:
The charge generation functions are extracted from the light emitting elements themselves and placed into separate, dedicated charge generation elements positioned between the light emitting elements. This extraction eliminates current leakage paths that would occur within integrated structures while maintaining manufacturing simplicity through modular assembly of standardized components
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 improves luminance efficiency and electroluminescent lifetime while minimizing current short/leakage paths, achieving better performance compared to single light emitting element devices.
Implementation Method 1
an inorganic n-type semiconductor material that can inject electrons into a light emitting element adjacent the first layer of the charge generation element
Implementation Method 2
a hole injection material that can inject holes into a light emitting element adjacent the second layer of the charge generation element
Implementation Method 3
A light emitting element can include a layer comprising an emissive material comprising quantum dots
Data Source
AI summary
A light emitting device comprising: a pair of electrodes; two or more light emitting elements disposed between the electrodes in a stacked arrangement, wherein a light emitting element comprises a layer comprising an emissive material, and a charge generation element disposed between adjacent light emitting elements in the stacked arrangement, the charge generation element comprising a first layer comprising an inorganic n-type semiconductor material, and a second layer comprising a hole injection material. A charge generation is also disclosed.