OLED Compound (S-A)n-T for Efficient Energy Transfer
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Solution Overview
Problem
In electronic devices like OLEDs, the lack of control over the distribution of components in traditional vapor deposition or solution processing leads to inefficient energy transfer between phosphorescent and fluorescent emitter compounds, resulting in reduced efficiency due to statistical distribution and poor film-forming properties of small molecules.
Innovation Solution
A compound of the formula (S-A)n-T is introduced, where S is a monovalent group acting as an absorbing dye, T is a phosphorescent emitter unit, and A is a divalent group linking S and T covalently, ensuring efficient energy transfer and improved film-forming properties by positioning the emitter units optimally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional vapor deposition or solution processing is used to deposit layers in OLEDs, then the deposition process can be performed, but the distribution of components becomes statistical and uncontrolled, leading to inefficient energy transfer
Solution Approach 1:
The invention divides the system into separate functional layers: a phosphorescent emitter layer and a fluorescent emitter layer, each with controlled composition. This segmentation allows independent optimization of each layer's component distribution while maintaining efficient energy transfer through controlled interlayer proximity, resolving the contradiction between distribution control and process complexity.
Solution Approach 2:
The patent introduces a host matrix material as an intermediary that facilitates controlled energy transfer between phosphorescent and fluorescent emitters. The host matrix provides a structured environment that enables predictable energy transfer pathways while simplifying the deposition process, as all components can be co-deposited from solution without requiring complex sequential processing.
2Use of energy by moving object
If phosphorescent emitter compounds are used in OLEDs, then efficiency can be improved, but the triplet-triplet annihilation causes roll-off effect at high excitation densities, reducing efficiency
Solution Approach 1:
The invention separates phosphorescent and fluorescent emitters into different layers, allowing the phosphorescent layer to efficiently generate triplet excitons without the roll-off effect, while the fluorescent layer converts these excitons to singlet states for efficient light emission. This segmentation eliminates the triplet-triplet annihilation problem that occurs when phosphorescent emitters are used alone at high excitation densities.
Solution Approach 2:
The host matrix acts as an intermediary that mediates energy transfer between the phosphorescent and fluorescent layers. It accepts energy from the phosphorescent emitter and transfers it to the fluorescent emitter, enabling efficient energy utilization while avoiding the harmful triplet-triplet annihilation that would occur in a pure phosphorescent system at high excitation densities.
3Ease of manufacture
If small molecule emitter compounds are used, then the materials can be processed from solution, but they exhibit poor film-forming properties
Solution Approach 1:
The patent creates composite materials by combining small molecule emitter compounds with host matrix materials in specific ratios. The host matrix provides the structural framework that enables good film-forming properties, while the small molecule emitters provide the desired optical functions. This composite approach allows solution processing of small molecules while achieving reliable film formation.
Solution Approach 2:
The invention optimizes the local composition and structure of the emitting layers by carefully selecting host matrix materials and emitter concentrations. This local quality control ensures that each layer has the appropriate properties for its function: the phosphorescent layer is optimized for triplet exciton generation, while the fluorescent layer is optimized for efficient light emission, both with good film-forming properties.
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 compound ensures efficient energy transfer between phosphorescent and fluorescent units, enhancing the performance and stability of electronic device layers, particularly in OLEDs, by ensuring optimal positioning and improved film formation.
Implementation Method 1
energy transfer occurs between the singlet emitter and the phosphorescent metal complex according to the Förster transfer mechanism
Implementation Method 2
energy transfer occurs between the singlet emitter and the phosphorescent metal complex according to the Förster transfer mechanism
Implementation Method 3
energy transfer occurs between the singlet emitter and the phosphorescent metal complex according to the Förster transfer mechanism or Dexter energy transfer
Implementation Method 4
phosphorescent emitter unit T; T is an n-valent group comprising a phosphorescent emitter unit
Implementation Method 5
organic or polymeric light-emitting diodes (OLEDs or PLEDs)
Data Source
AI summary
The present invention relates to compounds of the general formula (S-A)n-T, in which at least one fluorescent group S is linked via a divalent group A to a phosphorescent group T, to the use thereof in an electronic device, and also to a formulation and to an electronic device, both comprising the new compounds.