Cross-linkable Carrier Transport Material for OLEDs
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Solution Overview
Problem
The conventional solution process for manufacturing OLEDs faces challenges due to the dissolution of hole transport and light emitting layers, limiting the production of high-quality OLEDs, as materials like Spiro-2CBP dissolve TAPC, leading to inefficiencies in current efficiency and power efficiency.
Innovation Solution
A carrier transport material is developed through a reaction process involving aromatic compounds and polycyclic aromatic hydrocarbons (PAHs) with cross-linkable functional groups, allowing for cross-linking via heating or ultraviolet irradiation, which prevents dissolution by solvents and enhances electron confinement, thereby improving OLED efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the solution process is used to manufacture OLEDs with conventional materials (TAPC and Spiro-2CBP), then mass production can be achieved, but the Spiro-2CBP dissolves the TAPC hole transport layer, leading to poor device quality and limited manufacturing precision
Solution Approach 1:
The patent changes the chemical and physical parameters of the hole transport layer by using a cross-linkable compound that undergoes cross-linking reaction upon UV irradiation or heating. This transformation alters the layer's solubility and structural integrity, preventing dissolution by subsequent Spiro-2CBP coating while maintaining compatibility with the solution processing method for mass production
Solution Approach 2:
The patent employs a composite material system consisting of the cross-linkable hole transport compound combined with photoinitiators or curing agents. This composite structure enables the hole transport layer to form a cross-linked network that resists solvent attack from subsequent layers, thereby maintaining layer integrity during mass production processes
2Device complexity
If conventional hole transport materials are used without cross-linking, then the solution process can be simplified, but the materials are dissolved by solvents in subsequent layers, reducing reliability and device performance
Solution Approach 1:
The patent applies preliminary action by incorporating cross-linkable functional groups and photoinitiators into the hole transport layer before subsequent layer deposition. The cross-linking reaction is activated in advance (either during or immediately after hole transport layer formation), creating a stable, solvent-resistant structure that prevents dissolution when Spiro-2CBP and other materials are subsequently applied
Solution Approach 2:
The patent changes the chemical state of the hole transport material from a soluble, processable form to an insoluble, cross-linked network through UV irradiation or thermal treatment. This parameter change occurs at a specific stage in the manufacturing process, transforming the material's properties to achieve the desired reliability without compromising the overall process simplicity
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 carrier transport material effectively prevents solvent-induced dissolution and enhances OLED device efficiency, particularly in high-brightness operations, with demonstrated improvements in power and current efficiency across various color emissions.
Implementation Method 1
a cross linking reaction can be activated in the molecular compound through heating or ultraviolet irradiation because the molecular compound has at least one cross-linkable functional group
Implementation Method 2
a cross linking reaction can be activated in the molecular compound through heating or ultraviolet irradiation
Data Source
AI summary
The present invention provides a carrier transport material formed by completing a reaction process of at least one aromatic compound and at least one polycyclic aromatic hydrocarbons (PAHs), wherein a cross linking reaction can be activated in the molecular compound through heating or ultraviolet irradiation because the molecular compound has at least one cross-linkable functional group. Therefore, when the carrier transport material is applied in an OLED, the carrier transport material would not be dissolved by the solvent included in the next coated material because the carrier transport material has been cured after the cross linking reaction is carried out. Moreover, because the carrier transport material would simultaneously perform an electron confining functionality when being used as a hole transport layer, the device efficiency of the OLED having the carrier transport material is obviously enhanced during the high-brightness operation especially.