Conjugated Polymers with Polar Linkages for OLED Charge Transport
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Solution Overview
Problem
Conventional hole transport materials like TPD and NPB have low thermal stability and morphological instability, making them unsuitable for long-lifetime OLED devices, and polymeric charge transport materials are difficult to fabricate due to solvent solubility issues, which hinder the development of efficient organic electronic/optoelectronic devices.
Innovation Solution
Development of hole or electron injection polymers and prepolymers with polar groups and copolymers comprising conjugated or non-conjugated structures connected by ether, ester, urethane, urea, carbonate, nitrogen, amide, or imide groups, allowing solubility in polar solvents and facilitating the formation of stable charge injection/transport layers with adjustable turn-on voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional small hole transport molecules (TPD, NPB) are used, then high charge carrier mobility is achieved, but thermal stability and morphological stability are poor
Solution Approach 1:
The patent employs composite material design by incorporating rigid aromatic groups (naphthalene, phenanthrene, pyrene) into polymeric charge transport materials. These rigid aromatic structures provide thermal and morphological stability while maintaining charge carrier mobility through conjugated systems. The composite approach combines the benefits of small molecule mobility with polymeric stability.
Solution Approach 2:
The patent changes the molecular structure parameters by introducing rigid aromatic groups and extending conjugation lengths in the polymeric materials. This structural parameter modification directly improves thermal stability (raising Tg) and morphological stability while preserving or enhancing charge carrier mobility through improved electronic structure.
2Stability of the object's composition
If polymeric charge transport materials are used, then thermal stability is improved, but fabrication is difficult due to solvent solubility issues
Solution Approach 1:
The patent modifies the solubility parameters of polymeric charge transport materials by introducing specific side chain structures and polar groups. These parameter changes enable the materials to dissolve in common organic solvents, making spin-coating and other solution-based fabrication methods feasible while maintaining thermal stability through the core rigid aromatic structure.
3Duration of action of stationary object
If charge transport materials with high thermal stability are developed, then device lifetime is improved, but injection barrier between charge transport layer and electrodes increases
Solution Approach 1:
The patent applies local quality modification by introducing specific functional groups (amine, cyano, carbonyl) at the interfaces between charge transport layers and electrodes. These localized functional groups provide good energy level matching and charge injection properties without compromising the overall thermal stability provided by the rigid aromatic core structures.
Solution Approach 2:
The patent uses composite material design with interface-optimized functional groups combined with thermally stable aromatic cores. This creates a multi-functional material that simultaneously achieves low injection barriers through interface engineering and high thermal stability through the core structure, resolving the contradiction between device lifetime and injection efficiency.
Data Source
AI summary
The present invention discloses hole or electron injection polymers and prepolymers, hole or electron transport polymers and prepolymers, which comprises a plurality of conjugated or non-conjugated structures with electronic function and a plurality of connecting structures, wherein the connecting structure is used to connect different conjugated or non-conjugated structures with electronic function, and the connecting structure comprises any one or any combination of the following group: ether based group, ester based group, urethane based group, urea based group, carbonate based group, nitrogen atom based group, amide based group, and imide based group. Moreover, this invention also discloses a method for forming the mentioned charge injection or transport polymers and prepolymers. Additionally, this invention provides hole injection layer or hole transport layer or electron injection layer or electron transport layer comprising copolymers with a first structure unit with hole injecting/transporting property and a second structure unit with electron injecting/transporting property.