Spiro-9,9'-Bifluorene Hole Transport Layer for OLED Efficiency
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Solution Overview
Problem
Current light-emitting elements using organic compounds have limitations in achieving high luminous efficiency due to the low generation ratio of triplet excited states, leading to restricted internal quantum efficiency and power consumption.
Innovation Solution
Incorporating a spiro-9,9′-bifluorene derivative with a high triplet excitation energy level as a hole-transporting layer in conjunction with a phosphorescent compound in the light-emitting layer to enhance luminous efficiency and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fluorescent compound is used as the light-emitting substance, then the device structure is simple, but the internal quantum efficiency is limited to 25% due to low triplet excited state generation
Solution Approach 1:
The patent changes the emission mechanism parameter from fluorescence to phosphorescence by introducing a phosphorescent compound, enabling triplet excited state utilization and achieving internal quantum efficiency exceeding 25%
Solution Approach 2:
The patent uses a composite system combining a phosphorescent compound with a host material having high triplet excitation energy, creating a material system that efficiently generates and utilizes triplet excited states for light emission
2Use of energy by moving object
If a phosphorescent compound is used to improve internal quantum efficiency, then luminous efficiency increases, but the requirement for host material with high triplet excitation energy increases device complexity
Solution Approach 1:
The patent specifies precise parameter ranges for the host material, including triplet excitation energy of 2.1 eV or higher and specific HOMO/LUMO energy levels, to ensure efficient energy transfer and high luminous efficiency while maintaining device simplicity
3Weight of moving object
If organic compounds are used for light emission, then the device is thin and light in weight, but power consumption is high due to limited internal quantum efficiency
Solution Approach 1:
The patent changes the emission mechanism from fluorescence to phosphorescence, enabling utilization of triplet excited states and achieving internal quantum efficiency exceeding 25%, thereby reducing power consumption while maintaining the lightweight organic compound structure
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 use of spiro-9,9′-bifluorene derivative with a high T1 level and hole-transporting properties in the light-emitting element significantly improves luminous efficiency and reduces power consumption, achieving high color purity and heat resistance.
Implementation Method 1
Incorporating a spiro-9,9'-bifluorene derivative with a high triplet excitation energy level as a hole-transporting layer
Implementation Method 2
a compound which allows the forbidden transition of photoexcitation directly to the triplet excited state) is required. In other words, such a compound can be used as a photosensitizer and is useful. Also, such a compound often emits phosphorescence.
Implementation Method 3
Incorporating a spiro-9,9'-bifluorene derivative with a high triplet excitation energy level as a hole-transporting layer
Data Source
AI summary
It is an object to provide a light-emitting element with high luminous efficiency by using a hole transporting substance with a sufficiently high T1 level. Further, it is another object to provide a light-emitting device and an electronic appliance with low power consumption by using a hole transporting substance with a sufficiently high T1 level. The present invention provides a light-emitting element which has a first layer containing a spiro-9,9′-bifluorene derivative in which one amino group is combined and a second layer containing a phosphorescent compound between an anode and a cathode.