OLED Light-Emitting Device Doublet Excited State Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic light-emitting devices (OLEDs) face challenges in achieving high emission efficiency and reliability, particularly for blue-light-emitting devices, due to the short driving lifetime and instability of phosphorescent materials, which are necessary for high efficiency but suffer from long exciton lifetimes and high triplet excited states.
Innovation Solution
Incorporating an organic compound that emits light from a doublet excited state, such as an organic complex containing trivalent cerium, which has a short exciton lifetime and allows for 100% internal quantum efficiency without the need for materials with high triplet excited levels, enabling stable operation and efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphorescent materials are used to achieve high emission efficiency, then emission efficiency is improved, but device reliability deteriorates due to long exciton lifetimes and high triplet excited states
Solution Approach 1:
The patent changes the excited state parameter from triplet (phosphorescent) to doublet (fluorescent), which fundamentally alters the emission mechanism. This parameter change enables short exciton lifetimes while maintaining high emission efficiency, thereby resolving the contradiction between efficiency and reliability
Solution Approach 2:
The patent employs fluorescent materials with short exciton lifetimes (nanosecond scale) instead of phosphorescent materials with long exciton lifetimes (microsecond scale). This use of short-living excited states reduces the risk of degradation and improves device reliability while maintaining high emission efficiency through appropriate material selection
2Productivity
If phosphorescent materials with high triplet excited levels are used to achieve high emission efficiency, then emission efficiency is improved, but material stability deteriorates
Solution Approach 1:
The patent transitions from utilizing triplet excited states (requiring high triplet energy levels) to utilizing doublet excited states. This parameter change eliminates the need for materials with high triplet excited levels, thereby improving material stability while maintaining high emission efficiency through fluorescent materials with appropriate energy levels
3Reliability
If conventional fluorescent materials are used to improve reliability, then device reliability is improved, but emission efficiency deteriorates due to short exciton lifetimes and energy loss
Solution Approach 1:
The patent optimizes the excited state parameter by selecting fluorescent materials with doublet excited states that have appropriate energy levels. This enables efficient energy transfer from the host material to the fluorescent dopant while maintaining short exciton lifetimes, thereby achieving both high reliability and high emission efficiency simultaneously
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 approach results in a light-emitting device with high emission efficiency and reliability, particularly for blue light, by using a substance with a doublet excited state that avoids the limitations of phosphorescent materials, allowing for a wider material selection and improved device characteristics.
Implementation Method 1
Carriers are injected by application of voltage to the device, and recombination energy of the carriers is used, whereby light emission can be obtained from the light-emitting material
Implementation Method 2
the first substance emits light from a doublet excited state; and a doublet excited level of the first substance is lower than a singlet excited level of the second substance and higher than a triplet excited level of the second substance
Data Source
AI summary
A light-emitting device having high emission efficiency, reliability, and color purity is provided. The light-emitting device includes a first electrode, a second electrode, and an organic compound layer; the organic compound layer is positioned between the first electrode and the second electrode; the organic compound layer includes a light-emitting layer; the light-emitting layer includes a first substance and a second substance; the first substance emits light from a doublet excited state; a doublet excited level of the first substance is lower than a singlet excited level of the second substance and higher than a triplet excited level of the second substance; and the first substance emits light.