Light-Emitting Element Carrier Transport Control
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Solution Overview
Problem
Current current excitation type light-emitting elements have short lifetimes due to poor durability of hole-blocking layers, leading to inefficient light emission and reduced device longevity.
Innovation Solution
Incorporating layers with specific organic compounds that control carrier transport, where the first layer contains a hole-transporting organic compound and a second layer contains an electron-transporting organic compound, with the second compound degrading the transporting property of the third compound, to manage carrier balance and extend the light-emitting element's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a hole-blocking layer is provided in a light-emitting element using a phosphorescent material, then light emission efficiency is improved, but durability deteriorates and lifetime is reduced
Solution Approach 1:
The patent extracts the hole-blocking function from a separate layer and integrates it into the light-emitting layer itself by incorporating a hole-blocking organic compound. This eliminates the need for a dedicated hole-blocking layer that causes durability issues, while maintaining the light emission efficiency benefits.
Solution Approach 2:
The patent combines multiple functions into the light-emitting layer: light emission, hole blocking, and carrier balance control. By incorporating both the phosphorescent material and hole-blocking compound into the same layer, the patent achieves efficient light emission while improving durability through reduced carrier imbalance.
2Use of energy by moving object
If a hole-blocking layer is provided to improve light emission efficiency, then light emission is enhanced, but lifetime is reduced due to poor durability
Solution Approach 1:
The patent removes the separate hole-blocking layer that causes short lifetime and integrates its function into the light-emitting layer, thereby extending element lifetime while maintaining light emission efficiency.
Solution Approach 2:
The patent creates a composite light-emitting layer containing both phosphorescent material and hole-blocking organic compound. This composite structure achieves efficient light emission while improving lifetime by preventing carrier imbalance and reducing degradation.
3Device complexity
If carrier transport is not controlled, then device structure is simpler, but carrier imbalance occurs leading to reduced light emission efficiency and shorter lifetime
Solution Approach 1:
The patent merges carrier transport control functionality into the light-emitting layer by incorporating organic compounds with specific transporting properties. This maintains structural simplicity while achieving efficient carrier balance and high light emission efficiency.
Solution Approach 2:
The light-emitting layer is designed to perform multiple functions simultaneously: light emission, hole blocking, and carrier transport control. This multi-functionality eliminates the need for separate control layers, maintaining structural simplicity while ensuring efficient operation.
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 enhances light emission efficiency and extends the lifetime of the light-emitting element by suppressing carrier imbalance and reducing degradation of transport layers, resulting in improved recombination probabilities and sustained performance over time.
Implementation Method 1
the first layer contains a first organic compound with a hole-transporting property
Implementation Method 2
a second organic compound which degrades the hole-transporting property of the first organic compound and is dispersed in the first organic compound
Implementation Method 3
the second layer contains a third organic compound with an electron-transporting property
Implementation Method 4
a fourth organic compound which degrades the electron-transporting property of the third organic compound and is dispersed in the third organic compound
Implementation Method 5
recombination of these carriers (the electrons and holes) makes the light-emitting organic compound be in an excited state and emit light when the excited state returns to a ground state
Implementation Method 6
By applying voltage to these elements, light emission can be obtained from the light-emitting substance
Data Source
AI summary
It is an object to provide a light-emitting element having long lifetime. A light-emitting element is provided, in which a light-emitting layer, a first layer, and a second layer are provided between a first electrode and a second electrode; the first layer is provided between the light-emitting layer and the first electrode; the second layer is provided between the light-emitting layer and the second electrode; the first layer is a layer for controlling the hole transport; the second layer is a layer for controlling the electron transport; and light emission is obtained from the light-emitting layer by applying voltage to the first electrode and the second electrode such that the potential of the first electrode is higher than that of the second electrode.