Light-Emitting Device With Segmented Intermediate And Auxiliary Layers
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Solution Overview
Problem
Light-emitting devices with a common layer suffer from increased driving voltage, color mixing, and reduced lifespan due to the absence of an auxiliary layer, leading to variations in luminance with viewing angle.
Innovation Solution
A light-emitting device structure with a first emission layer, a first auxiliary layer, and a first intermediate layer, where the intermediate layer's energy levels facilitate improved hole injection and electron blocking, and a second emission layer with a dopant emitting light with a full width at half maximum (FWHM) of 35 nm or more to minimize spectral changes with angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common layer is used in light-emitting devices, then device complexity is reduced, but driving voltage increases due to high hole injection barrier
Solution Approach 1:
The common layer is segmented into two separate layers: a first intermediate layer positioned between the first emission layer and the second emission layer, and a first auxiliary layer positioned between the first intermediate layer and the first emission layer. This segmentation resolves the contradiction by allowing each layer to be optimized for specific functions, reducing the hole injection barrier and thus lowering driving voltage while maintaining structural simplicity.
2Ease of manufacture
If a common layer is used, then manufacturing is simplified, but color mixing occurs due to absence of auxiliary layer
Solution Approach 1:
The common layer is divided into functionally distinct segments: the first intermediate layer serves as an electron blocking layer to prevent color mixing, while the first auxiliary layer provides hole injection and transport functions. This segmentation enables effective prevention of color mixing while maintaining ease of manufacture through a systematic layer structure.
Solution Approach 2:
The first intermediate layer acts as an intermediary between the two emission layers, functioning as an electron blocking layer that prevents electrons from the second emission layer from migrating to the first emission layer, thereby preventing color mixing while maintaining manufacturing simplicity.
3Device complexity
If a common layer is used, then device structure is simplified, but lifespan is reduced due to electron leakage
Solution Approach 1:
Segmenting the common layer into the first intermediate layer (electron blocking) and the first auxiliary layer (hole transport) creates a more reliable structure that prevents electron leakage, thereby extending device lifespan while maintaining structural simplicity.
Solution Approach 2:
The first intermediate layer serves as an intermediary electron blocking barrier that prevents electrons from leaking into the first emission layer, thereby protecting the device and extending its operational lifespan while keeping the overall structure simple.
4Ease of manufacture
If a common layer is used, then manufacturing is easier, but luminance varies with angle due to resonance distance difference
Solution Approach 1:
Segmenting the common layer into distinct functional layers with optimized thicknesses allows for better control of optical resonance characteristics, reducing luminance variation with viewing angle while maintaining ease of manufacture.
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 reduces driving voltage, prevents color mixing, and maintains consistent luminance across viewing angles, enhancing the overall performance of the light-emitting device.
Implementation Method 1
an absolute value of a highest occupied molecular orbital (HOMO) energy level of the first intermediate layer is larger than an absolute value of a HOMO energy level of the first auxiliary layer and smaller than an absolute value of a HOMO energy level of the first emission layer
Implementation Method 2
an absolute value of a lowest unoccupied molecular orbital (LUMO) energy level of the first intermediate layer is larger than an absolute value of a LUMO energy level of the first auxiliary layer and smaller than an absolute value of a LUMO energy level of the first emission layer
Implementation Method 3
Holes provided from the anode and electrons provided from the cathode recombine in the emission layer to produce excitons. These excitons transit (e.g., transition or relax) from an excited state to a ground state, thereby generating light.
Data Source
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AI summary
A light-emitting device includes: a plurality of first electrodes respectively in a first sub-pixel, a second sub-pixel, and a third sub-pixel; a second electrode facing the plurality of first electrodes; a first emission layer in the first sub-pixel and configured to emit a first color light; a second emission layer in the second sub-pixel and configured to emit a second color light; a first layer that is integrated with the first sub-pixel, the second sub-pixel, and the third sub-pixel; a first auxiliary layer between the first layer and the first emission layer; and a first intermediate layer between the first auxiliary layer and the first emission layer. The first emission layer includes a first host and a first dopant. The first dopant is configured to emit light having a full width at half maximum (FWHM) of about 35 nm or more.