Organic EL Layer Formation Using Immiscible Solvent Coating
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Solution Overview
Problem
The existing methods for manufacturing organic electroluminescent elements face challenges in achieving high efficiency and low cost, particularly in forming multilayer structures using high molecular weight materials, which leads to reduced productivity and increased costs due to the complexity and expense of vacuum deposition processes.
Innovation Solution
A method involving the simultaneous coating of two layers on a substrate using coating solutions with immiscible solvents, followed by drying, to form an organic electroluminescent element with a light emission layer and adjacent layers such as a hole injecting layer, hole transporting layer, electron injecting layer, and electron transporting layer, allowing for the formation of a stable interface between layers without mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum deposition is used to manufacture organic EL elements with lower molecular weight materials, then high purity materials can be obtained and multilayer structures can be formed, but the operation becomes complex and expensive
Solution Approach 1:
The patent replaces the mechanical vacuum deposition system with a chemical solution-based coating system. Specifically, it uses spin coating or inkjet printing methods to deposit organic EL materials from solution, eliminating the need for complex vacuum equipment while achieving comparable or superior layer quality and simplifying the manufacturing process.
Solution Approach 2:
The patent changes the physical state of the EL materials from vapor phase (required for vacuum deposition) to solution phase. By dissolving the materials in appropriate solvents and applying them via liquid coating methods, the process operates at atmospheric pressure rather than requiring high vacuum conditions, thereby reducing operational complexity.
2Area of stationary object
If vacuum deposition is used for large size EL elements, then materials can be deposited, but it becomes difficult to manufacture and forms uneven layers
Solution Approach 1:
The patent replaces vacuum deposition with liquid coating methods (spin coating or inkjet printing) that are inherently more suitable for large-area deposition. These methods allow for uniform coating over large surfaces by controlling the flow and drying of liquid solutions, avoiding the unevenness problems associated with scaling up vacuum deposition.
Solution Approach 2:
The patent uses inkjet printing technology to precisely deposit materials in desired patterns across large areas. The inkjet method creates digital copies of the desired layer structure by selectively ejecting droplets, enabling uniform and accurate formation of EL layers over large substrates without the scaling limitations of vacuum deposition.
3Ease of manufacture
If wet process is used with high molecular weight EL materials, then low cost and large sized layers can be obtained, but multilayer structure formation becomes difficult due to material mixing
Solution Approach 1:
The patent segments the multilayer formation process into distinct sequential steps, where each layer is deposited, dried, and stabilized before the next layer is applied. This prevents mixing between layers by ensuring complete solvent evaporation and structural stabilization of each layer before subsequent coating, thereby enabling efficient multilayer formation with wet processes.
Solution Approach 2:
The patent applies preliminary drying and stabilization actions between layer depositions. By completely removing solvent and stabilizing each layer before applying the next, the method prevents interlayer mixing while maintaining the cost advantages of wet processing, thus improving multilayer formation 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
This approach enables the efficient and cost-effective manufacturing of organic electroluminescent elements by preventing material mixing during multilayer formation, thereby improving productivity and reducing manufacturing costs while maintaining high efficiency.
Implementation Method 1
simultaneous coating of two coating solutions on a substrate in contact with one another, wherein a first coating solution for a first layer and a second coating solution for a second layer are used, and solvents for the first coating solution and the second coating solution are immiscible with one another
Implementation Method 2
drying the coated to form the two layers on the substrate
Data Source
AI summary
Disclosed is a method of manufacturing an organic electroluminescent element comprising a substrate and provided thereon, a light emission layer and at least one layer of a hole injecting layer, a hole transporting layer, an electron injecting layer, and an electron transporting layer, two layers of the light emission layer and the at least one layer being adjacent to each other, the method comprising the steps of (a) providing a first coating solution employing a first organic solvent for one layer of the two layers and a second coating solution employing a second solvent for the other layer of the two layers, the first solvent being immiscible with the second solvent; (b) simultaneously coating the first and second coating solutions on the substrate so that the first coating solution is in contact with the second coating solution; and (c) drying the coated.