Spirofluorene Electron Transport Layer for OLED Durability
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Solution Overview
Problem
Triazine- and pyrimidine-based compounds used in organic electronics often have low glass transition temperatures, which negatively impact the durability and performance of OLED devices, while bulky molecular fragments required to increase Tg can disrupt charge carrier mobility.
Innovation Solution
The use of a compound with a spiro[benzo[de]anthracene-7,9′-fluorene structural unit in the electron transport layer, allowing for high Tg and charge carrier mobility, and potentially combined with additives like metals or metal complexes, to enhance the performance of OLED devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If triazine- and pyrimidine-based compounds are used as electron transport materials, then the device structure can be simplified and manufacturing can be eased, but the glass transition temperature becomes low which deteriorates device durability and performance
Solution Approach 1:
The patent modifies the molecular structure of triazine- and pyrimidine-based compounds by introducing specific substituents (R1-R6 groups including aryl, heteroaryl, alkyl groups) to increase the glass transition temperature while preserving the electron transport functionality. This parameter change in molecular structure allows the material to maintain both ease of manufacture and improved device durability through higher thermal stability.
Solution Approach 2:
The patent creates composite electron transport materials by combining triazine- or pyrimidine-based core structures with various functional groups and substituents. These composite molecular structures achieve both the desired high glass transition temperature and maintained electron transport capability, resolving the contradiction between ease of manufacture and device durability.
2Reliability
If bulky molecular fragments are introduced to increase glass transition temperature, then device durability is improved, but charge carrier mobility is significantly disturbed which deteriorates overall device performance
Solution Approach 1:
The patent applies local quality by introducing bulky molecular fragments only at specific positions (R1-R6 substituents) on the triazine- or pyrimidine core structure, rather than throughout the entire molecule. This localized approach allows the material to achieve high glass transition temperature in specific regions while maintaining good charge carrier mobility in the conjugated core regions essential for electron transport.
Solution Approach 2:
The patent carefully controls the parameters of the molecular structure by selecting specific substituents with appropriate sizes and electronic properties. This parameter optimization allows achieving sufficient glass transition temperature increase without excessive bulk that would hinder charge carrier mobility, thus resolving the contradiction between device durability and power efficiency.
3Duration of action of stationary object
If the glass transition temperature is increased to improve device lifetime, then material stability is enhanced, but the charge carrier mobility decreases due to molecular structure modifications
Solution Approach 1:
The patent optimizes molecular parameters by selecting specific substituent types and combinations on the triazine- or pyrimidine core to achieve the right balance. The substituent parameters (size, electronic nature, position) are carefully chosen to increase glass transition temperature sufficiently for long device lifetime while maintaining charge carrier mobility above acceptable thresholds for efficient OLED operation.
Solution Approach 2:
The patent designs composite molecular structures where the triazine- or pyrimidine core provides the electron transport pathway for high charge carrier mobility, while the attached substituents provide the structural rigidity and thermal stability for long device lifetime. This composite approach allows both contradictory requirements to be satisfied simultaneously.
Data Source
AI summary
The invention relates to an organic electronic device comprising at least one electron transport, electron injection or electron generation layer comprising a compound of Formula (I) wherein all positions which are not linked to a -(A)a-L moiety at a *- position may be bound to another substituent; A is selected from substituted or unsubstituted aryl or heteroaryl; L is selected from substituted or unsubstituted aryl or heteroaryl or a group (II) and (III); and “a” is an integer from 0 to 2; to the compounds of Formula (I) as well as to display and lightning devices comprising the same.