Cross-linked Organic Compound for OLED Interface Blocking
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Solution Overview
Problem
In organic light-emitting diodes (OLEDs) manufactured by a solution process, the mixing of materials between the hole transport layer and the emissive layer results in a rough interface, leading to reduced luminous efficiency and increased power consumption due to imbalanced charge injection and recombination.
Innovation Solution
An organic compound with hole transfer properties, featuring a dibenzothiophene core and vinyl groups for cross-linking, is used to form a cured product that prevents material mixing between the hole transport layer and the emissive layer, ensuring a smooth interface and enhanced morphological characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a solution process is used to form the hole transport layer and emissive layer, then manufacturing complexity is reduced and productivity is improved, but material mixing occurs at the interface resulting in rough morphology and reduced luminous efficiency
Solution Approach 1:
A blocking layer is introduced between the hole transport layer and the emissive layer to prevent material mixing. This intermediary layer acts as a barrier that stops the solvent from dissolving the lower layer while allowing the solution process to continue, thereby maintaining both manufacturing efficiency and interface quality.
Solution Approach 2:
The patent changes the solvent parameters by selecting a blocking layer material that is insoluble in the solvent used for the emissive layer. This parameter change (selecting appropriate material solubility characteristics) prevents material mixing while allowing the solution process to proceed, resolving the contradiction between productivity and manufacturing precision.
2Loss of substance
If a solution process is used to manufacture OLEDs, then waste of organic material is reduced and cost is lowered, but material mixing between layers occurs leading to imbalanced charge injection and increased power consumption
Solution Approach 1:
The blocking layer serves as a mediator that prevents material mixing between the hole transport layer and emissive layer. By introducing this intermediate barrier, the patent maintains the benefits of solution processing (reduced material waste) while preventing the harmful effects (material mixing leading to imbalanced charge injection and increased power consumption).
3Reliability
If conventional hole transporting materials are used in the hole transport layer, then charge transport function is achieved, but material mixing with the emissive layer occurs resulting in rough interface morphology
Solution Approach 1:
The blocking layer is introduced as an intermediary between the hole transport layer and emissive layer. This blocking layer maintains the charge transport function of the hole transport layer while preventing material mixing that would otherwise occur at the interface, thereby preserving both reliability and shape.
Solution Approach 2:
The patent applies local quality by making the blocking layer selectively positioned at the interface where material mixing occurs. This localized intervention prevents mixing only at the critical interface region while maintaining the overall charge transport function of the hole transport layer.
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 use of the cured organic compound in the hole transport layer of OLEDs results in balanced charge injection, improved luminous efficiency, and reduced power consumption, enabling low-voltage operation.
Implementation Method 1
capable of forming cross-links by a curing process
Data Source
AI summary
Compounds, and polymers thereof, useful dopants for light emitting diodes and light emitting display devices are disclosed. The compounds have the following structure Formula 1:wherein R1, R2, R3, R4, L1, L2, L3, L4, a, b, c and d are as defined herein. Light emitting diodes including compounds of Formula 1 (and polymers thereof, i.e., compounds of Formula 3), light emitting devices including the same as well as methods associated with preparation and use of such compounds, polymers and devices are also provided.