Light-Emitting Element Carrier Balance and Lifetime
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current current-excitation light-emitting elements have short lifetimes due to poor durability of hole-blocking layers, leading to inefficient light emission and rapid degradation.
Innovation Solution
A light-emitting element structure is developed with layers for controlling carrier transport, comprising a light-emitting layer sandwiched between a hole-transporting layer and an electron-transporting layer, where the layers contain specific organic compounds with optimized molecular orbital levels and dipole moments to manage hole and electron transport efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hole-blocking layer is provided to improve light emission efficiency, then light emission efficiency is improved, but durability deteriorates and lifetime becomes very short
Solution Approach 1:
The patent extracts the hole-blocking function from a separate layer and integrates it into the light-emitting layer itself by using a phosphorescent complex that inherently blocks holes while maintaining high light emission efficiency and durability
Solution Approach 2:
The phosphorescent complex in the light-emitting layer serves multiple functions simultaneously: it emits light efficiently and blocks hole transport, eliminating the need for a separate hole-blocking layer that would compromise durability
2Device complexity
If carrier transport is not controlled, then device structure is simpler, but carrier balance is poor and lifetime is short
Solution Approach 1:
The patent applies local quality by using different organic compounds with specific properties (hole-transporting, electron-transporting, electron-trapping) at different locations within the layers to control carrier transport and achieve carrier balance
Solution Approach 2:
The patent uses composite materials by combining multiple organic compounds (first organic compound with hole-transporting property, second organic compound with electron-transporting property, third organic compound with electron-transporting property, and fourth organic compound with electron-trapping property) within the layers to achieve controlled carrier transport and improved lifetime
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 structure significantly enhances the lifetime of light-emitting elements by controlling carrier balance and reducing degradation, leading to improved light emission efficiency and reliability.
Implementation Method 1
the first organic compound has a hole-transporting property
Implementation Method 2
the second organic compound has an electron-transporting property
Implementation Method 3
the third organic compound has an electron-transporting property
Implementation Method 4
the fourth organic compound has an electron-trapping property
Implementation Method 5
By applying voltage to this element, light can be emitted from the substance having a light-emitting property
Data Source
AI summary
It is an object of the present invention to provide a light-emitting element with high light emission efficiency and with a long lifetime. A light-emitting device comprises a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein 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 from the light-emitting layer is obtained when voltage is applied to the first electrode and the second electrode so that potential of the first electrode is higher than potential of the second electrode.