Mixed-Host Light-Emitting Element for Low-Capacitance Displays
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Solution Overview
Problem
There is a persistent demand for an organic electroluminescence element with low driving voltage and improved image quality in display devices.
Innovation Solution
A light-emitting element comprising a first electrode, a second electrode, and a light-emitting layer with specific host compounds and phosphorescent and fluorescent compounds, including hole-transporting and electron-transporting host compounds with controlled surface potentials, and additional layers such as hole transport and electron transport regions, to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a phosphorescent compound with positive giant surface potential is used in the light-emitting layer, then light emission efficiency is improved, but capacitance increases
Solution Approach 1:
The patent changes the giant surface potential parameter of the host compounds from positive to negative. Specifically, the hole-transporting host compound and electron-transporting host compound both have negative giant surface potentials, which is a fundamental parameter change that resolves the capacitance issue while maintaining light emission efficiency through optimized charge transport properties
Solution Approach 2:
The patent uses a composite light-emitting layer comprising multiple host compounds (hole-transporting host compound and electron-transporting host compound) with specific negative giant surface potentials, combined with phosphorescent and fluorescent compounds. This composite material system achieves both low capacitance and high light emission efficiency through synergistic interactions between the components
2Device complexity
If conventional host compounds are used in the light-emitting layer, then device structure is simple, but driving voltage is high
Solution Approach 1:
The patent changes the giant surface potential parameter of the host compounds to negative values, which fundamentally alters the charge transport characteristics and reduces the driving voltage required for device operation, while maintaining a relatively simple device structure
Solution Approach 2:
The patent optimizes the local properties of the light-emitting layer by selecting host compounds with specific negative giant surface potentials and appropriate HOMO-LUMO energy levels, creating localized regions with optimized charge transport properties that reduce overall device driving voltage
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 achieves low capacitance characteristics and improved image quality in display devices, addressing the need for low driving voltage and enhanced performance.
Implementation Method 1
a phosphorescent compound, and a fluorescent compound
Implementation Method 2
a phosphorescent compound, and a fluorescent compound
Implementation Method 3
an organic electroluminescence element in which holes and electrons respectively injected from a first electrode and a second electrode recombine in a light-emitting layer. In the light-emitting layer, a light-emitting material that includes an organic compound emits light upon this recombination of holes and electrons
Data Source
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AI summary
Embodiments provide a light-emitting element and a display device that includes the light-emitting element. The light-emitting element includes a first electrode, a second electrode disposed on the first electrode, and a light-emitting layer disposed between the first electrode and the second electrode. The light-emitting layer includes a hole-transporting host compound, an electron-transporting host compound, a phosphorescent compound, and a fluorescent compound, wherein at least one of the hole-transporting host compound and the electron-transporting host compound has a lower giant surface potential than the phosphorescent compound.