Organic Light-Emitting Element with Exciplex for Broad Spectrum
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Solution Overview
Problem
Current light-emitting elements using thermally activated delayed fluorescent materials face challenges in achieving high emission efficiency and controlling multi-color light emission, particularly in obtaining desired emission colors and broad emission spectra with low power consumption.
Innovation Solution
A light-emitting element is developed using a combination of two organic compounds that form an exciplex, where one compound converts triplet-excitation energy into light emission, with specific energy level configurations and ratios to optimize light emission from both the exciplex and the first organic compound, allowing for efficient generation of singlet excited states and broad emission spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thermally activated delayed fluorescent material is used to convert triplet excited state into light emission, then emission efficiency is improved, but it is difficult to control the light emission to obtain desired emission colors and broad emission spectra
Solution Approach 1:
The light-emitting layer is segmented into multiple functional components: a host material, a thermally activated delayed fluorescent material (guest), and a triplet state quenching material. Each component performs a specific function - the host provides the matrix, the TADF material converts triplet excitons to singlet excitons for light emission, and the triplet state quenching material prevents non-radiative decay. This segmentation allows independent optimization of each component to achieve both high efficiency and controllable emission color.
Solution Approach 2:
The invention optimizes the energy level parameters of the materials involved. Specifically, the triplet state energy level of the triplet state quenching material is controlled to be lower than that of the TADF material, enabling efficient energy transfer. The singlet state energy level of the TADF material is optimized to match the emission requirements. By adjusting these energy level parameters, the invention achieves both high emission efficiency and controllable emission color.
2Use of energy by moving object
If phosphorescent compounds are used to convert triplet excited state energy into light emission, then emission efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention replaces expensive phosphorescent compounds with a more economical system using TADF materials combined with triplet state quenching materials. The TADF material has a short excited state lifetime, which prevents triplet state accumulation and eliminates the need for expensive phosphorescent dopants. This approach reduces material costs and simplifies the overall device structure while maintaining high emission efficiency.
Solution Approach 2:
The invention changes the key parameter of excited state lifetime by using TADF materials with short singlet state lifetimes instead of long-lived phosphorescent states. This parameter change fundamentally alters the emission mechanism, allowing efficient triplet-to-singlet conversion without requiring phosphorescent materials. The result is a simplified device structure with reduced complexity in terms of material selection and device fabrication.
3Use of energy by moving object
If exciplex is used as thermally activated delayed fluorescent material, then emission efficiency is improved, but it is difficult to further increase emission efficiency and control multi-color light emission
Solution Approach 1:
The invention merges the advantages of exciplex systems with TADF materials by forming an exciplex between the host material and the TADF guest material. This exciplex formation enhances the TADF effect and improves emission efficiency. Additionally, the invention combines multiple TADF materials with different emission colors in the same light-emitting layer, enabling multi-color light emission while maintaining high efficiency. The triplet state quenching material is integrated into this system to further optimize performance.
Solution Approach 2:
The invention uses composite materials consisting of the host material, TADF guest material, and triplet state quenching material working together in a synergistic manner. The host-TADF exciplex forms a composite emitting system with enhanced TADF characteristics. By selecting appropriate combinations of materials with complementary properties, the invention achieves both high emission efficiency and controllable multi-color emission, overcoming the limitations of using single exciplex or TADF materials alone.
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 results in a light-emitting element with high emission efficiency, capable of producing a broad emission spectrum and low power consumption, enabling the creation of novel light-emitting and display devices with improved performance.
Implementation Method 1
light emission from the triplet excited state is referred to as phosphorescence
Implementation Method 2
In a thermally activated delayed fluorescent material, a singlet excited state is generated from a triplet excited state by reverse intersystem crossing, and the singlet excited state is converted into light emission
Implementation Method 3
a singlet excited state is generated from a triplet excited state by reverse intersystem crossing
Implementation Method 4
By recombination of the injected electrons and holes, the organic compound having a light-emitting property is put in an excited state to obtain light emission from the excited organic compound having a light-emitting property
Data Source
AI summary
Providing a light-emitting element emitting light in a broad emission spectrum. A combination of a first organic compound and a second organic compound forms an exciplex. The first organic compound has a function of converting triplet-excitation energy into light emission. The lowest triplet excitation level of the second organic compound is higher than or equal to the lowest triplet excitation level of the first organic compound, and the lowest triplet excitation level of the first organic compound is higher than or equal to the lowest triplet excitation level of the exciplex. Light emission from a light-emitting layer includes light emission from the first organic compound and light emission from the exciplex.