Organic Light-Emitting Element Carrier Transport Control
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Solution Overview
Problem
Current light-emitting elements using organic compounds for electroluminescence face challenges in achieving high light emission efficiency and long lifetime due to poor durability of hole-blocking layers, leading to short lifespans.
Innovation Solution
A light-emitting element structure is developed with specific organic compound layers for controlling carrier transport, including a hole-transporting layer and an electron-transporting layer, where the weight percentage of certain organic compounds is optimized to enhance light emission efficiency and extend the element's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hole-blocking layer is provided to improve light emission efficiency, then light emission efficiency is improved, but lifetime is shortened due to poor durability
Solution Approach 1:
The patent changes the functional parameters of the layer by providing both hole-blocking and electron-transporting properties through specific material selection and composition ratios. The layer contains a first organic compound (electron-transporting) and a second organic compound (hole-blocking) in controlled weight ratios, transforming a single-function layer into a multi-functional layer that blocks holes while maintaining electron transport capability.
Solution Approach 2:
The patent applies multi-functionality by designing a layer that simultaneously performs hole-blocking and electron-transporting functions. This eliminates the need for separate hole-blocking and electron-transporting layers, and specifically replaces the conventional hole-blocking layer (which has poor durability) with a multi-functional layer that combines hole-blocking with electron-transporting capabilities, thereby improving both efficiency and lifetime.
2Productivity
If conventional hole-blocking layer is used, then light emission efficiency is improved, but durability is poor leading to short lifetime
Solution Approach 1:
The patent uses composite materials by combining two different organic compounds in a specific layer: a first organic compound with electron-transporting property and a second organic compound with hole-blocking property. This composite structure allows the layer to exhibit both hole-blocking and electron-transporting properties simultaneously, replacing the conventional single-material hole-blocking layer with a composite material system that provides both functionality and improved durability.
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 structure achieves high light emission efficiency and a longer lifetime by controlling carrier transport, reducing degradation and maintaining performance over time.
Implementation Method 1
electrons and holes are injected into a layer including an organic compound having a light-emitting property from a pair of electrodes by voltage application to a light-emitting element, so that current flows therethrough. Then, these carriers (electrons and holes) are recombined; thus, the organic compound having a light-emitting property is brought into an excited state. The organic compound having a light-emitting property returns to a ground state from the excited state, thereby emitting light.
Implementation Method 2
electrons and holes are injected into a layer including an organic compound having a light-emitting property from a pair of electrodes by voltage application to a light-emitting element, so that current flows therethrough. Then, these carriers (electrons and holes) are recombined; thus, the organic compound having a light-emitting property is brought into an excited state. The organic compound having a light-emitting property returns to a ground state from the excited state, thereby emitting light.
Data Source
AI summary
It is an object of the present invention to provide a light-emitting element with high light emission efficiency. It is another object of the present invention to provide a light-emitting element with a long lifetime. A light-emitting device is provided, which includes a light-emitting layer, a first layer, and a second layer between first electrode and a second electrode, 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 a 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.