Organic Light Emitting Device Intermediate Layers Charge Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional organic light emitting devices have relatively poor lifetime characteristics due to the imbalance in the flow speeds of holes and electrons, which leads to deterioration during operation.
Innovation Solution
Incorporating a first intermediate layer with a first host and dopant, a second intermediate layer with only the dopant, and a third intermediate layer with a second host and dopant, between the electrodes and the emission layer, to balance the flow speeds of holes and electrons, thereby enhancing the device's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic light emitting device structure is used, then device simplicity is maintained, but lifetime characteristics deteriorate due to imbalance in hole and electron flow speeds
Solution Approach 1:
The patent divides the intermediate layer into three distinct sub-layers (first, second, and third intermediate layers) with different material compositions. The first intermediate layer contains a first host and first dopant, the second intermediate layer contains only dopant without host, and the third intermediate layer contains a second host and first dopant. This segmentation allows each sub-layer to contribute differently to charge transport, balancing hole and electron flow speeds to improve lifetime characteristics.
Solution Approach 2:
Each intermediate layer is assigned specific local properties: the first intermediate layer provides hole transport with host-dopant complex, the second intermediate layer provides dopant-only region for charge balance, and the third intermediate layer provides additional host-dopant interaction. This local quality differentiation optimizes charge carrier flow in different regions of the device.
2Duration of action of stationary object
If intermediate layers are added to balance charge flow, then lifetime is improved, but device structure complexity increases
Solution Approach 1:
The intermediate region is segmented into three functional sub-layers, each with specific material compositions (host-dopant, dopant-only, host-dopant). This segmentation enables precise control over charge transport properties without requiring complete redesign of the entire device structure.
Solution Approach 2:
The three intermediate layers act as intermediary structures between the electrodes and emission layer, mediating the charge transport process. The dopant-containing layers specifically facilitate balanced hole and electron flow, serving as intermediaries that resolve the charge imbalance problem without requiring fundamental changes to the device architecture.
3Reliability
If dopant-only layer is introduced, then charge flow balance is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent varies the compositional parameters across the three intermediate layers: the first and third layers contain host-dopant complexes with specific doping concentrations, while the second layer contains dopant only. This parameter variation (host presence/absence, dopant concentration) enables precise control of charge transport properties.
Solution Approach 2:
The intermediate structure uses composite material combinations: host materials combined with dopant materials in specific ratios and configurations. The dopant-only second intermediate layer represents a unique composite configuration that optimizes charge balance while maintaining manufacturability through sequential deposition processes.
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 balanced flow of holes and electrons results in increased lifetime and improved luminescence characteristics without a substantial increase in operating voltage, as demonstrated by the comparison with conventional devices in the provided examples.
Implementation Method 1
a first intermediate layer including a first host and a first dopant, a second intermediate layer including the first dopant, and a third intermediate layer including a second host and the first dopant, between a first electrode and an emission layer
Data Source
AI summary
An organic light emitting device includes a substrate; a first electrode; a second electrode; and an organic layer including an emission layer between the first electrode and the second electrode. The organic layer includes a first intermediate layer including a first host and a first dopant, a second intermediate layer including the first dopant, and a third intermediate layer including a second host and the first dopant interposed between the first electrode and the emission layer. The organic light emitting device has a long lifetime.