Organic Light Emitting Device Crosslinked Layer Stability
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Solution Overview
Problem
The luminance life of light emitting devices, particularly those with organic electroluminescent layers, is not sufficient according to existing technologies.
Innovation Solution
A light emitting device is designed with a specific configuration including an anode, a cathode, a first organic layer containing a phosphorescent material, and a second organic layer comprising a crosslinked body of a crosslinkable material and a phosphorescent material, where both layers use the same phosphorescent compound and a crosslinkable material with specific chemical structures to enhance stability and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional organic electroluminescent device structure is used, then the device can be manufactured with standard processes, but the luminance life is insufficient
Solution Approach 1:
The patent applies preliminary action by forming a crosslinked body structure in advance within the organic layers before the device operates. The crosslinkable material is pre-installed in the organic layers, and through crosslinking treatment (thermal or UV), a three-dimensional crosslinked network structure is formed beforehand. This preliminary crosslinked structure prevents molecular migration and degradation during operation, thereby extending luminance life and improving reliability.
Solution Approach 2:
The patent uses composite materials by combining crosslinkable materials (such as organometallic compounds with cyclooctene structures) with phosphorescent dopants and host materials to form composite organic layers. This composite structure integrates the stabilizing crosslinked network with the light-emitting functional components, achieving both improved luminance life through crosslinking and maintained electroluminescence performance through the phosphorescent composite system.
2Duration of action of stationary object
If crosslinkable materials are introduced to improve luminance life, then the stability of organic layers improves, but the device structure becomes more complex
Solution Approach 1:
The patent merges multiple functions into a single organic layer by incorporating crosslinkable materials, phosphorescent dopants, and host materials into one integrated layer structure. The crosslinkable material serves dual purposes: as a structural stabilizer that forms a protective network and as part of the electroluminescent system that can participate in charge transport and energy transfer. This merging eliminates the need for separate stabilization layers, thereby extending luminance life without significantly increasing structural complexity.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical structure of organic layer components to include crosslinkable functional groups (such as cyclooctene rings). This structural parameter change enables the material to undergo crosslinking transformation under external stimuli (heat or UV light), fundamentally changing the physical state from linear molecules to a three-dimensional network. This parameter change achieves enhanced stability and extended luminance life while maintaining compatibility with standard organic layer fabrication processes.
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
This configuration significantly improves the luminance life of the light emitting device by ensuring better stability and performance of the organic layers.
Implementation Method 1
a second organic layer disposed between the anode and the cathode and comprising a crosslinked body of a crosslinkable material
Implementation Method 2
a first organic layer disposed between the anode and the cathode and comprising a phosphorescent material
Data Source
AI summary
A light emitting device is provided which contains an anode, a cathode, and two organic layers disposed between the anode and the cathode. The first organic layer contains a phosphorescent material and the second organic layer contains a crosslinked body of a crosslinkable material and a phosphorescent material. The two phosphorescent materials contain the same phosphorescent compound represented by formula (1), and the crosslinkable material is a compound represented by formula (3):In formula (1), M represents a metal atom, n1 is ≥1, n2 is ≥0, E1 and E2 represent a carbon atom, L1 and L2 represent an aromatic heterocyclic ring, and A1-G1-A2 represents an anionic bidentate ligand.In formula (3), mB1 to mB3 represent an integer of ≥0, Ar7 may represent an aromatic hydrocarbon group, LB1 may represent a divalent group, and X″ may represent a crosslinkable group.