Exciplex OLED Emitter Architecture for Low-Voltage High Efficiency
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Solution Overview
Problem
Existing light-emitting elements using thermally activated delayed fluorescent materials face challenges in efficiently generating singlet excited states from triplet excited states, leading to low luminous efficiency, high drive voltage, and high power consumption.
Innovation Solution
A light-emitting element is designed with a light-emitting layer containing two organic compounds that form an exciplex, where one compound converts triplet excitation energy into light emission and another converts singlet excitation energy, optimizing energy transfer and reducing drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermally activated delayed fluorescent materials are used to convert triplet excitation energy into light emission, then light emission can be achieved, but the efficiency of generating singlet excited states from triplet excited states is low
Solution Approach 1:
The patent introduces an exciplex as an intermediary system between the phosphorescent compound and the fluorescent compound. The exciplex forms through interaction between these two compounds and serves as a mediator that facilitates efficient reverse intersystem crossing from triplet to singlet excited states, thereby improving the overall luminous efficiency of the light-emitting element
Solution Approach 2:
The patent employs a composite light-emitting layer containing multiple compounds (phosphorescent compound, fluorescent compound, and host material) that form an exciplex. This composite material system combines the advantages of different compounds to achieve both efficient triplet excitation energy conversion and effective singlet excited state generation
2Device complexity
If conventional light-emitting materials are used, then the structure can be simple, but the drive voltage remains high and power consumption is high
Solution Approach 1:
The patent optimizes the energy level parameters of the light-emitting layer by carefully selecting compounds with appropriate HOMO and LUMO levels. This parameter optimization enables better energy matching between the phosphorescent and fluorescent compounds, facilitating efficient energy transfer and reducing the drive voltage required for 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
The solution enhances luminous efficiency, reduces drive voltage, and lowers power consumption while maintaining a highly reliable operation.
Implementation Method 1
In a light-emitting element, a singlet excited state is generated from a triplet excited state by reverse intersystem crossing
Implementation Method 2
excitation energy is supplied from the exciplex to a third organic compound which has a function of converting singlet excitation energy into light emission
Implementation Method 3
research and development have been extensively conducted on light-emitting elements using electroluminescence (EL)
Data Source
AI summary
A light-emitting element having high luminous efficiency is provided. The light-emitting element includes a first organic compound, a second organic compound, and a third organic compound. The first organic compound and the second organic compound, in combination, are capable of forming an exciplex. The first organic compound is a phosphorescent compound and the third organic compound is a fluorescent compound. Light emitted from the light-emitting element includes light emitted from the third organic compound to which excitation energy is supplied from the exciplex formed by the first organic compound and the second organic compound.