Light-Emitting Device Electron Injection Efficiency
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Solution Overview
Problem
Existing light-emitting devices using organic electroluminescence elements often fail to achieve optimal luminous efficiency due to the combination of switching elements like TFTs and light-emitting portions, depending on their configuration and layering order.
Innovation Solution
A light-emitting device comprising a first electrode, a second electrode, a light-emitting layer with a phosphor, a metal layer, and insulating layers that allow electron injection, with a first power supply applying voltage between the electrodes and a second power supply applying a voltage with opposite polarity to the metal layer and cathode, enhancing electron injection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a TFT and light-emitting portion are combined to form a light-emitting device, then the device can be driven and controlled, but the luminous efficiency may not be optimal due to configuration and layering issues
Solution Approach 1:
The patent divides the light-emitting device into distinct functional layers: a light-emitting layer containing phosphor, a metal layer, and insulating layers with specific thicknesses. This segmentation allows each layer to be optimized independently for electron injection and light emission, resolving the contradiction between achieving high luminous efficiency and maintaining manageable device complexity.
Solution Approach 2:
The patent changes key parameters including the thickness of insulating layers, the material composition of the metal layer, and the voltage polarity applied to different layers. By optimizing these parameters, the device achieves improved luminous efficiency without requiring overly complex configurations.
2Loss of energy
If additional layers are added to improve electron injection, then luminous efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The metal layer in the patent serves multiple functions: it acts as an electron injection layer, a reflective layer for light extraction, and a structural support layer. This multi-functionality improves electron injection efficiency without requiring separate dedicated layers for each function, thereby maintaining manufacturing simplicity.
Solution Approach 2:
The insulating layers with specific thicknesses act as intermediaries between the metal layer and the light-emitting layer, facilitating controlled electron injection while preventing direct contact that would cause short circuits. This intermediary approach improves electron injection efficiency without adding excessive structural complexity.
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 achieves improved luminous efficiency by optimizing electron injection and reducing the need for additional layers, lowering drive voltage, and simplifying manufacturing while maintaining cost-effectiveness.
Implementation Method 1
a second insulating layer provided on a light-emitting layer side of the metal layer and having a thickness allowing electron injection from the second electrode to the light-emitting layer
Implementation Method 2
a light-emitting layer provided between the first electrode the second electrode and including a phosphor
Implementation Method 3
a light-emitting layer provided between the first electrode the second electrode and including a phosphor
Implementation Method 4
a first power supply that applies a voltage between the first electrode and the second electrode
Implementation Method 5
a second power supply that applies, between the metal layer and the second electrode, a voltage having a polarity, of the second electrode, being opposite to a polarity of the voltage applied by the first power supply
Data Source
AI summary
A light-emitting device includes a first electrode, a second electrode facing the first electrode, a light-emitting layer provided between the first electrode the second electrode and including a phosphor, a layered body including a metal layer, a first insulating layer provided on a second electrode side of the metal layer, and a second insulating layer provided on a light-emitting layer side of the metal layer, and having a thickness that allows electron injection from the second electrode to the light-emitting layer, a first power supply configured to apply a voltage between the first electrode and the second electrode, and a second power supply configured to apply, between the metal layer and the second electrode, a voltage of which polarity of the second polarity is opposite to a polarity of the second electrode of a voltage applied by the first power supply between the first electrode and the second electrode.