P-Doped Small Molecular Electrolyte for OLED Work Function Control
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Solution Overview
Problem
Conventional interfacial materials for organic electronic devices, such as PEDOT:PSS and conjugated polyelectrolytes, face issues like exciton quenching, anode oxidation, and batch-to-batch variability due to their polymer-based nature, limiting their commercialization and efficiency in controlling the work function for metal electrodes.
Innovation Solution
A p-doped conjugated small molecular electrolyte with a compound structure represented by Formula 1, which is solution-processable and neutral, acting as a hole transport material to control the work function effectively without anode oxidation and batch-to-batch problems, is introduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PEDOT:PSS is used as a hole transport material, then solution processability is achieved, but severe exciton quenching occurs at the interface with the active layer
Solution Approach 1:
The patent changes the chemical composition parameters by replacing the conventional PEDOT:PSS system with a small molecular electrolyte containing a conjugated compound and lithium salt. This parameter change maintains solution processability while eliminating the exciton quenching issue through different chemical properties of the small molecular electrolyte system
Solution Approach 2:
The invention uses a composite material system consisting of a conjugated compound (providing hole transport capability) and a lithium salt (providing ionic conductivity and doping). This composite approach achieves both solution processability and compatibility with the active layer by combining materials with complementary properties
2Reliability
If PEDOT:PSS is used as a hole transport material, then work function control is achieved, but anode oxidation occurs due to strong acidity
Solution Approach 1:
The patent changes the chemical nature parameter from acidic (PEDOT:PSS) to neutral (small molecular electrolyte with lithium salt). This parameter change maintains the ability to control work function through ionic doping while eliminating the harmful acidity that causes anode oxidation
Solution Approach 2:
The small molecular electrolyte system uses stable, non-acidic lithium salt compounds that provide durable work function control without the corrosive effects of acidic materials, effectively replacing short-lived degraded materials with stable long-lasting alternatives
3Ease of manufacture
If conjugated polyelectrolytes are used as hole transport materials, then print processability is achieved, but batch-to-batch variability occurs due to polymer synthesis
Solution Approach 1:
The patent segments the material from polymer form to small molecular form. This segmentation allows each component (conjugated compound and lithium salt) to be synthesized and purified independently with high precision, then combined in controlled ratios, eliminating the batch-to-batch variability inherent in polymer synthesis while maintaining print processability
Solution Approach 2:
The invention creates a composite of small molecular conjugated compound and lithium salt that can be precisely formulated. This composite approach allows exact control of composition ratios and properties for each batch, achieving high manufacturing precision and reproducibility while maintaining solution and print processability
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 p-doped conjugated small molecular electrolyte enhances the reproducibility and efficiency of organic electronic devices by finely adjusting the work function, reducing corrosion and improving the performance of OLEDs and solar cells.
Implementation Method 1
it can be used as a hole transport material since there is no concern about the anode oxidation
Implementation Method 2
Such interfacial layers form an ohmic contact between the metal electrode and organic materials by controlling the work function of the electrode effectively
Implementation Method 3
superscript '+' in the square bracket indicates an oxidized portion of a main chain of the small molecule
Data Source
AI summary
Disclosed are a p-doped conjugated small molecular electrolyte containing a compound represented by Formula 1 and an organic electronic device using the same as a hole transport material.[Ar2—Ar1—Ar2]+ <Formula 1>wherein, in Formula 1, Ar1 is any one selected from the following Compound Group 1, Ar2 is any one selected from the following Compound Group 2a or the following Compound Group 2b, and superscript “+” in the square bracket indicates an oxidized portion of a main chain of the small molecule.