Emission Layer Doping Structure for Lower-Voltage Light Emission
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Solution Overview
Problem
Existing light-emitting devices face issues with non-uniform emission layers due to insufficient source application, leading to degraded device characteristics and increased driving voltage.
Innovation Solution
Incorporating a depletion layer and/or low-doped layer in the emission layer, with controlled dopant concentrations and layer thicknesses, to ensure uniform dopant distribution and enhanced hole and electron mobility, thereby improving device characteristics and reducing driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the emission layer is formed without a depletion layer or low-doped layer, then the manufacturing process is simpler, but the dopant distribution becomes non-uniform and device characteristics degrade
Solution Approach 1:
The emission layer is segmented into three distinct regions: a first emission layer with higher dopant concentration, a second emission layer (depletion layer) with lower or zero dopant concentration, and a third emission layer with higher dopant concentration. This segmentation creates a non-uniform dopant distribution pattern that prevents source aggregation and ensures uniform emission characteristics across the device.
Solution Approach 2:
Different regions of the emission layer are assigned different dopant concentrations tailored to their specific functional requirements. The central depletion layer has reduced dopant concentration to prevent source aggregation, while the adjacent first and third emission layers have higher dopant concentrations to ensure adequate charge carrier generation. This local quality variation optimizes both uniformity and device performance.
2Power
If the dopant concentration is increased to improve emission, then the driving voltage decreases, but the dopant distribution becomes non-uniform and device characteristics worsen
Solution Approach 1:
The patent applies local quality by creating regions with different dopant concentrations within the emission layer. The first and third emission layers have higher dopant concentrations to provide sufficient charge carriers and maintain low driving voltage, while the central second emission layer has lower or zero dopant concentration to prevent source aggregation and ensure uniform dopant distribution throughout the layer.
Solution Approach 2:
The patent changes the dopant concentration parameter spatially within the emission layer. By varying the dopant concentration from high in the first and third emission layers to low or zero in the central second emission layer, the patent achieves both adequate emission performance (low driving voltage) and uniform dopant distribution, preventing source aggregation issues.
3Speed
If the emission layer thickness is reduced to improve device response, then the charge carrier mobility decreases, but the dopant distribution becomes insufficient
Solution Approach 1:
The patent applies local quality by concentrating dopants in specific regions (first and third emission layers) rather than uniformly distributing them throughout the entire emission layer. This allows the emission layer to maintain a thin overall thickness for fast response while ensuring adequate dopant quantity in the regions where it is most needed for charge carrier generation and mobility.
Solution Approach 2:
The patent changes the dopant concentration parameter to compensate for reduced emission layer thickness. By increasing dopant concentration in the first and third emission layers, the patent ensures sufficient charge carrier generation and mobility even when the overall emission layer thickness is reduced to improve device response speed.
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 results in a uniform emission layer with increased mobility of charge carriers, leading to improved device performance and reduced driving voltage.
Implementation Method 1
Holes provided from the first electrode move toward the emission layer through the hole transport region, and electrons provided from the second electrode move toward the emission layer through the electron transport region. Carriers, such as holes and electrons, recombine in the emission layer to produce excitons. When the excitons transition from an excited state to a ground state, light is emitted.
Implementation Method 2
the second dopant emits delayed fluorescence
Data Source
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AI summary
Embodiments provide a light-emitting device and an electronic apparatus including the same. The light-emitting device includes a first electrode, a second electrode facing the first electrode, an emission layer between the first electrode and the second electrode, a hole transport region between the first electrode and the emission layer, and a hole transport region between the emission layer and the second electrode. The emission layer includes a first emission layer, a second emission layer, and a third emission layer, which are sequentially arranged from the hole transport region, wherein the second emission layer has a different configuration from the first emission layer and third emission layer.