Aromatic Amine Hole-Transport Material for Low-Index OLED Layers
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Solution Overview
Problem
Existing organic light-emitting devices face challenges with low outcoupling efficiency due to refractive index differences between layers, which affect carrier-transport properties and reliability, making it difficult to form low refractive index layers without compromising device performance.
Innovation Solution
Development of novel aromatic amine compounds for hole-transport and hole-injection layers with specific refractive indices and carrier-transport properties, including monoamine compounds with aromatic groups bonded to a nitrogen atom, sp3 hybrid orbital configurations, and fluorene skeletons, to enhance emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low refractive index layer is formed in the EL layer, then outcoupling efficiency is improved, but carrier-transport property deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the organic compound by introducing specific saturated hydrocarbon groups (sp3 hybridized carbon atoms) into the molecular structure. This structural modification reduces the refractive index while maintaining carrier-transport capability through the aromatic amine core structure, thus resolving the trade-off between outcoupling efficiency and carrier-transport property
Solution Approach 2:
The patent creates a composite molecular structure combining aromatic amine groups (for carrier transport) with saturated hydrocarbon groups (for low refractive index). This molecular-level composite allows simultaneous achievement of high outcoupling efficiency and good carrier-transport property by integrating the beneficial properties of different structural motifs
2Loss of energy
If a low refractive index layer is formed in the EL layer, then external quantum efficiency is improved, but device reliability deteriorates
Solution Approach 1:
The patent modifies molecular parameters by controlling the proportion of sp3 hybridized carbon atoms (saturated hydrocarbon content) to achieve optimal refractive index reduction while maintaining device reliability through the stable aromatic amine framework, thus improving external quantum efficiency without sacrificing reliability
3Reliability
If organic compounds with many unsaturated bonds are used, then carrier-transport property is improved, but refractive index increases
Solution Approach 1:
The patent changes the hybridization state parameter of carbon atoms in the molecular structure, specifically incorporating sp3 hybridized (saturated) hydrocarbon groups instead of purely sp2 unsaturated structures. This parameter change reduces the refractive index while the aromatic amine core maintains adequate carrier-transport property through its electronic structure
Data Source
AI summary
A material for a hole-transport layer includes a monoamine compound. The first aromatic group, the second aromatic group, and the third aromatic group are bonded to the nitrogen atom of the monoamine compound. The first and second aromatic groups each independently include 1 to 3 benzene rings. One or both of the first and second aromatic groups have one or more hydrocarbon groups each having 1 to 12 carbon atoms each forming a bond only by the sp3 hybrid orbitals. The total number of the carbon atoms in the hydrocarbon group in the first or second aromatic group is 6 or more. The total number of the carbon atoms in all of the hydrocarbon groups in the first and second aromatic groups is 8 or more. The third aromatic group is a substituted or unsubstituted monocyclic condensed ring or a substituted or unsubstituted bicyclic or tricyclic condensed ring.