Metal Amide Hole Injection Layers for Deep-HOMO OLEDs
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Solution Overview
Problem
Existing hole injection layer materials, such as dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (CNHAT), fail to effectively promote hole injection into hole transport layers with HOMO levels further away from the vacuum level, leading to high drive voltages and inefficient operation of OLEDs, particularly for blue and green phosphorescent emitters.
Innovation Solution
Employing a charge-neutral metal amide compound as the hole injection layer material, which facilitates effective hole injection into deep HOMO levels, reducing drive voltage and improving voltage stability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional hole injection layer materials (e.g., CNHAT) are used, then the device structure is simple and easy to manufacture, but the hole injection efficiency into deep HOMO levels is insufficient, leading to high drive voltages
Solution Approach 1:
The patent introduces a hole injection layer comprising a metal amide compound as an intermediary material between the anode and the hole transport layer. This intermediary layer specifically facilitates hole injection into deep HOMO levels that conventional materials cannot effectively access, thereby resolving the contradiction between manufacturing simplicity and injection efficiency
Solution Approach 2:
The patent changes the chemical and electronic parameters of the hole injection layer by using metal amide compounds with specific molecular structures (Formula Ia-Ib) and HOMO levels (5.8-6.5 eV). This parameter change enables effective hole injection into deep HOMO levels while maintaining ease of manufacture through solution processing
2Device complexity
If conventional hole injection layer materials are used, then the manufacturing process is simple, but the drive voltage is too high and voltage stability is poor
Solution Approach 1:
The metal amide compound-based hole injection layer acts as a mediator that reduces the energy barrier for hole injection, thereby lowering the drive voltage and improving voltage stability without significantly increasing device complexity
Solution Approach 2:
The patent employs composite material strategy by combining metal amide compounds (such as LiTFSI, Mg(TFSI)2, AgTFSI, Mn(TFSI)2) with organic ligands to create a hole injection layer that achieves low drive voltage and high stability while maintaining relatively simple device structure
3Device complexity
If conventional hole injection layer materials are used, then the device structure is simple, but the external quantum efficiency is insufficient
Solution Approach 1:
The metal amide compound-based hole injection layer serves as an intermediary that enhances charge injection efficiency, which directly improves external quantum efficiency. This intermediary layer enables better hole injection into the hole transport layer without requiring complex device structural modifications
Solution Approach 2:
By changing the HOMO level parameter of the hole injection layer to 5.8-6.5 eV using metal amide compounds, the patent achieves improved external quantum efficiency (5-10% or higher) while maintaining relatively simple device structure
Data Source
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AI summary
The present invention relates to metal amides of general Formula Ia and for their use as hole injection layer (HIL) for an Organic light-emitting diode (OLED), and a method of manufacturing Organic light-emitting diode (OLED) comprising an hole injection layer containing a metal amide of general Formula Ia: