Fluorescent-Phosphorescent EL Layers for Efficient White-Light Emission
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Solution Overview
Problem
Existing light-emitting elements face challenges in achieving high emission efficiency and effective multicolor or white light emission.
Innovation Solution
A light-emitting element structure is designed with a first light-emitting layer containing a fluorescent material and host material, and a second light-emitting layer containing a phosphorescent material, an exciplex, and a specific energy transfer mechanism to enhance emission efficiency, allowing for multicolor or white light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light-emitting layer with phosphorescent material is used, then device complexity is reduced, but emission efficiency and multicolor/white light emission capability are insufficient
Solution Approach 1:
The light-emitting element is divided into multiple light-emitting layers: a first light-emitting layer containing fluorescent material and a second light-emitting layer containing phosphorescent material. This segmentation allows each layer to contribute differently to light emission, improving overall emission efficiency while enabling multicolor or white light output through the combination of fluorescent and phosphorescent emissions.
2Use of energy by moving object
If a first light-emitting layer with fluorescent material and a second light-emitting layer with phosphorescent material are combined, then emission efficiency and multicolor/white light emission are improved, but device complexity increases
Solution Approach 1:
The patent combines fluorescent and phosphorescent light-emitting layers in a single light-emitting element structure. The first light-emitting layer with fluorescent material and the second light-emitting layer with phosphorescent material are integrated to work together, merging their emission mechanisms to achieve high emission efficiency and multicolor or white light emission from a unified device.
3Ease of manufacture
If conventional light-emitting structures are used, then manufacturing is simpler, but degradation resistance and stable high-luminance emission are insufficient
Solution Approach 1:
The light-emitting element employs composite material structures including the first light-emitting layer with fluorescent material and host compound, and the second light-emitting layer with phosphorescent material, exciplex, and specific organic compounds. These composite structures enhance degradation resistance and enable stable high-luminance emission by combining materials with complementary properties that protect against degradation while maintaining emission performance.
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 improves emission efficiency and enables stable, high-luminance multicolor or white light emission with reduced degradation, suitable for various display and lighting applications.
Implementation Method 1
The second light-emitting layer includes a phosphorescent material
Implementation Method 2
Energy transfer from the exciplex to the phosphorescent material is described
Implementation Method 3
The first light-emitting layer includes a fluorescent material
Implementation Method 4
research and development of a light-emitting element (organic EL element) which uses an organic compound and utilizes electroluminescence (EL)
Data Source
AI summary
Emission efficiency of a light-emitting element is improved. The light-emitting element has a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a fluorescent material and a host material. The second light-emitting layer includes a phosphorescent material, a first organic compound, and a second organic compound. An emission spectrum of the second light-emitting layer has a peak in a yellow wavelength region. The first organic compound and the second organic compound form an exciplex.