Light-Emitting Element With Segmented Electron Injecting Layers
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Solution Overview
Problem
Conventional light-emitting elements face challenges in reducing driving voltage while maintaining high manufacturing yields and achieving good color purity, as increasing the thickness of the electron injecting layer to control the emission spectrum often results in increased power consumption unless specific organic compounds like bathocuproin are used.
Innovation Solution
A light-emitting element configuration featuring a first layer with a light-emitting material, a second layer with an n-type semiconductor, and a third layer with a p-type semiconductor, where the layers are sequentially formed between the anode and cathode, allowing for increased thickness without raising the driving voltage, using materials such as zinc oxide, vanadium oxide, and chromium oxide to enhance hole mobility and control the optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the electron injecting layer is increased to control the emission spectrum and improve color purity, then the manufacturing yield is improved, but the driving voltage is drastically increased and power consumption is increased
Solution Approach 1:
The electron injecting layer is divided into multiple sub-layers with different thicknesses and compositions. The first electron injecting layer has a greater thickness than the second electron injecting layer, allowing optimized electron injection while controlling the optical path length for improved color purity without requiring excessive total thickness that would increase power consumption.
Solution Approach 2:
Different regions of the electron injecting layer structure are assigned different properties: the first electron injecting layer uses an organic compound with specific electron mobility characteristics and greater thickness for primary electron injection, while the second electron injecting layer uses a different organic compound with complementary properties to fine-tune the emission spectrum and improve color purity locally at the interface with the light-emitting layer.
2Productivity
If the thickness of the electron injecting layer is increased to improve manufacturing yield, then more electrons are available for injection, but the driving voltage is drastically increased
Solution Approach 1:
The electron injecting layer is segmented into multiple sub-layers where the first electron injecting layer provides the primary electron supply with greater thickness for improved manufacturing yield, while the second electron injecting layer with smaller thickness and different material properties optimizes the electron injection efficiency, preventing excessive driving voltage increase.
Solution Approach 2:
The electron injecting layer structure combines multiple organic compounds with different electron mobility characteristics and energy levels. This composite structure allows optimized electron injection by leveraging the complementary properties of different materials, achieving high electron supply for improved manufacturing yield while maintaining acceptable driving voltage levels.
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 configuration enables a light-emitting element that operates at low driving voltage, consumes low power, and maintains good color purity, while also improving manufacturing yields by effectively managing the optical path and carrier mobility.
Implementation Method 1
a second layer containing n-type semiconductor
Implementation Method 2
a third layer containing p-type semiconductor
Implementation Method 3
holes injected from the anode and electrons injected from the cathode are recombined with each other at an emission center within the layer containing a light-emitting material to lead the formation of molecular excitons, and the molecular excitons return to the ground state while radiating energy as light
Implementation Method 4
the thickness of the electron injecting layer is increased to vary the optical path between a cathode and a light-emitting layer, so that an emission spectrum emitted to outside can be controlled due to the effect of interference of light
Data Source
AI summary
In the present invention, a light-emitting element operating at low driving voltage, consuming low power, emitting light with good color purity and manufactured in high yields can be obtained. A light-emitting element is disclosed with a configuration composed of a first layer containing a light-emitting material, a second layer, a third layer are formed sequentially over an anode to be interposed between the anode and a cathode in such a way that the third layer is formed to be in contact with the cathode. The second layer is made from n-type semiconductor, a mixture including that, or a mixture of an organic compound having a carrier transporting property and a material having a high electron donor property. The third layer is made from p-type semiconductor, a mixture including that, or a mixture of an organic compound having a carrier transporting property and a material having a high electron acceptor property.