Metal Complex Hole Injection Layers for Stable OLED Voltage
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Solution Overview
Problem
There is a need to improve the performance of semiconductor materials, semiconductor layers, and electronic devices, particularly in achieving stable operating voltage over time, by enhancing the characteristics of compounds within these materials, including the hole injection layer, to balance hole and electron injection effectively and enable deposition through vacuum thermal evaporation suitable for mass production.
Innovation Solution
A compound represented by Formula I, comprising a metal M coordinated with a charge-neutral ligand L, is used in the semiconductor layer, specifically designed to form a hole injection layer that is non-emissive and has a HOMO level further away from the vacuum level, allowing for improved hole injection characteristics and stability, and can be deposited via vacuum thermal evaporation under conditions suitable for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hole injection materials are used, then device structure is simple, but operating voltage stability deteriorates over time
Solution Approach 1:
The patent employs composite hole injection materials comprising a matrix compound and a metal complex compound with specific molecular structures. The matrix compound provides structural framework while the metal complex compound enhances hole injection efficiency and stability. This composite approach resolves the contradiction by achieving improved operating voltage stability through the synergistic combination of materials, where the metal complex (e.g., iridium or platinum-based) embedded in the organic matrix provides both structural integrity and superior charge injection properties without excessive complexity.
Solution Approach 2:
The patent modifies key parameters of hole injection materials including HOMO level positioning (making it further from vacuum level), molecular weight range (400-2000 g/mol), and chemical composition (incorporating specific heteroaryl groups and metal complexes). These parameter changes enable optimized hole injection characteristics and improved voltage stability while maintaining manufacturability through vacuum thermal evaporation.
2Ease of operation
If hole injection layer is optimized for performance, then operating voltage improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes deposition parameters including rate onset temperature (200-255°C), molecular weight range (400-2000 g/mol), and compound composition to enable vacuum thermal evaporation under mass production conditions. The HOMO level is positioned further from vacuum level to improve hole injection while the molecular weight and thermal properties are tuned to ensure suitable vapor pressure and deposition characteristics, resolving the contradiction between performance optimization and manufacturing ease.
3Productivity
If metal complexes are used in semiconductor layer, then hole injection efficiency improves, but device lifetime decreases
Solution Approach 1:
The patent creates a composite hole injection layer combining a stable organic matrix compound with metal complex compounds (iridium or platinum-based). The matrix compound provides structural stability and long-term durability, while the metal complex enhances hole injection efficiency. This composite structure resolves the contradiction by allowing the metal complex to improve injection performance while the robust organic matrix protects against degradation, achieving both high efficiency and extended device lifetime.
4Ease of operation
If HOMO level is positioned further from vacuum level, then hole injection characteristics improve, but electron injection balance deteriorates
Solution Approach 1:
The patent positions the HOMO level further from vacuum level (more negative potential) to improve hole injection characteristics by creating a larger energy offset that facilitates hole extraction. Simultaneously, the patent carefully selects the LUMO level and uses specific matrix compounds to maintain electron injection capability, achieving charge balance through coordinated optimization of both HOMO and LUMO levels rather than focusing solely on HOMO positioning.
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 compound enhances the operating voltage stability and efficiency of electronic devices like OLEDs, ensuring balanced hole and electron injection, with a non-emissive contribution to the visible emission spectrum and suitable deposition conditions for mass production, leading to improved device performance and longevity.
Implementation Method 1
can be deposited via vacuum thermal evaporation under conditions suitable for mass production
Data Source
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AI summary
The present invention relates to compound represented by Formula (I) wherein M is a metal; L is a charge-neutral ligand, which coordinates to the metal M; n is an integer selected from 1 to 4, which corresponds to the oxidation number of M; m is an integer selected from 0 to 2; R1, R2 and R3 are substituents; at least one R1, R2 and/or R3 is selected from a substituted C2 to C24 heteroaryl group, wherein at least one substituent is selected from halogen, F, CI, CN, partially or fully fluorinated C1 to C6 alkyl, partially or fully fluorinated C1 to C6 alkoxy. The present invention also relates to a semiconductor material comprising at least one compound of formula (I), an semiconductor layer comprising at least one compound of formula (I) and an electronic device comprising at least one compound of formula (I). Exemplary compounds are e.g. metal complexes of 3-(2,3,5-trifluoro-6-(trifluoromethyl)pyridin-4-yl)pentane-2,4-dione, such as e.g. tris(((Z)-4-oxo-3-(2,3,5-trifluoro-6-(trifluoromethyl)pyridin-4-yl)pent-2-en-2-yl)oxy) iron or bis(((Z)-4-oxo-3-(2,3,5-trifluoro-6-(trifluoromethyl)pyridin-4-yl)pent-2-en-2-yl)oxy) copper