Organic Molecules for OLED Emitter Materials
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optoelectronic devices, such as OLEDs, face inefficiencies and stability issues due to the use of metal complexes, particularly in achieving high photoluminescence quantum yields and emission maxima in the blue, sky-blue, or green spectral range without metal ions.
Innovation Solution
Development of purely organic molecules with a specific chemical structure, comprising a first chemical moiety linked to three second chemical moieties via single bonds, exhibiting thermally activated delayed fluorescence (TADF) and photoluminescence quantum yields of 20% or more, specifically designed for use in OLEDs to enhance efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metal complexes are used as emitter materials in OLEDs, then photoluminescence quantum yield and device efficiency are improved, but device stability and material purity are worsened due to metal ion contamination and degradation
Solution Approach 1:
The invention extracts and eliminates metal ions from the emitter material system, transitioning from metal complexes to purely organic molecules. This removal of metal contaminants directly addresses the stability issue while maintaining the desired photoluminescence performance through carefully designed organic structures with appropriate HOMO-LUMO energy levels and TADF characteristics.
Solution Approach 2:
The invention employs composite molecular structures combining electron-donating moieties (carbazole, triphenylamine) with electron-accepting moieties (fluorinated pyridine, cyano groups) to create purely organic emitter materials. This composite approach enables achievement of high photoluminescence quantum yield and stable TADF emission without requiring metal complexes.
2Productivity
If emission maxima in the blue spectral range (420-480 nm) are achieved with high quantum yield, then device efficiency is improved, but material stability is worsened due to high energy state degradation
Solution Approach 1:
The invention modifies molecular parameters including introducing fluorine atoms at specific positions (positions 2 and 6 of pyridine ring) to adjust HOMO-LUMO energy gaps and optimize emission wavelengths in the blue range (420-480 nm). The fluorine substitution also enhances molecular stability by strengthening C-F bonds and reducing non-radiative decay pathways, thereby maintaining material stability while achieving high efficiency blue emission.
3Reliability
If purely organic molecules are designed to replace metal complexes, then material purity and device stability are improved, but achieving high photoluminescence quantum yield and TADF emission is worsened
Solution Approach 1:
The invention applies local quality by creating distinct functional moieties within the molecule: electron-donating carbazole/triphenylamine units provide high electron density for efficient excitation, while electron-accepting fluorinated pyridine/cyano units create appropriate LUMO levels. This spatial separation of electron-rich and electron-poor regions facilitates efficient charge transfer and achieves high photoluminescence quantum yield (20% or more) purely through organic structures.
Solution Approach 2:
The invention utilizes dynamic thermal activation to enable TADF emission. The molecular structure is designed with small singlet-triplet energy gaps that allow thermal energy at operating temperatures to promote triplet excitons to singlet states, which then emit photons. This dynamic thermal process enables high photoluminescence quantum yield without requiring metal complexes, achieving both material purity and high efficiency.
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 organic molecules achieve higher efficiencies and stability in OLEDs with comparable color, offering improved performance by utilizing TADF and specific chemical structures to optimize emission characteristics.
Implementation Method 1
The molecules according to the invention exhibit in particular thermally activated delayed fluorescence (TADF)
Data Source
Figure 1~2
AI summary
The invention relates to an organic compound for the use in optoelectronic devices. According to the invention, the organic molecule has - one first chemical moiety with a structure of formula I, and - three second chemical moieties, each with a structure of formula II, wherein the first chemical moiety is linked to each of the three second chemical moieties via a single bond; wherein # represents the binding site of a single bond linking the second chemical moiety to the first chemical moiety; Z is at each occurrence independently from another selected from the group consisting of a direct bond, CR3R4, C=CR3R4, C=O, C=NR3, NR3, O, SiR3R4, S, S(O) and S(O)2; LT is N or C-T; Lv is N or C-V; Lw is N or C-W; T, V, W is the binding site of a single bond linking the first chemical moiety to one of the three second chemical moieties or is R2; X, Y is the binding site of a single bond linking the first chemical moiety to one of the three second chemical moieties or is R1; Rc is the binding site of a single bond linking the first chemical moiety to one of the three second chemical moieties; and Rw is selected from the group consisting of CN and CF3.