OLED Layer Deposition via Kinetic Solvent Control
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Solution Overview
Problem
Existing processes for preparing OLEDs through solution-based methods are complex and time-consuming, requiring multiple steps and often result in defects at the interface between functional layers, leading to suboptimal device performance and limited material design flexibility.
Innovation Solution
A process involving the controlled deposition of organic functional materials using specific solvent combinations, where the absolute solubility of the first material in the second solvent is between 0.1 and 200 g/L, and the second solvent has a boiling point between 210 and 350°C, allowing for efficient and uniform layer formation without cross-linking, thereby preventing detachment or impairment of the first layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple process steps (inkjet printing, drying, cross-linking, vacuum deposition) are used to form OLED layers, then the device performance and layer definition are improved, but the process complexity and production time increase significantly
Solution Approach 1:
The patent combines multiple process steps into a single inkjet printing operation. The inkjet fluid contains both the organic semiconductor material and the cross-linkable binder in a unified formulation, allowing simultaneous deposition of functionally active layer and protective layer in one printing pass, eliminating separate drying and cross-linking steps
Solution Approach 2:
The inkjet fluid serves multiple functions: it acts as the solvent carrier for the organic semiconductor, provides the cross-linkable binder for layer protection, and enables direct patterning. The binder polymer performs both structural support and interface protection functions, reducing the need for additional specialized materials and process steps
2Reliability
If cross-linking is performed to prevent detachment and dissolution of the first functional layer, then the interface quality is improved, but the process time and temperature requirements increase
Solution Approach 1:
The cross-linkable binder is pre-incorporated into the inkjet fluid formulation at the appropriate concentration. The binder is already positioned and distributed throughout the first functional layer during the initial printing step, so the cross-linking capability is prepared in advance without requiring additional material deposition or processing steps
Solution Approach 2:
The patent uses a cross-linkable binder polymer with specific molecular weight and functional group concentration that enables cross-linking to proceed at reduced temperatures and shorter times compared to traditional small-molecule cross-linking systems. The polymer's inherent structure allows for faster network formation
3Reliability
If orthogonal solvent concepts are used to deposit successive layers, then layer detachment is prevented, but the material design flexibility and solubility options are restricted
Solution Approach 1:
The cross-linkable binder polymer acts as an intermediary between the first functional layer and the second functional layer. It provides a stable, cross-linked interface that prevents direct solvent-material interactions that would cause dissolution or detachment, while allowing the use of conventional solvents for subsequent layer deposition without requiring orthogonal solvent systems
Solution Approach 2:
The inkjet fluid is formulated as a composite material containing the organic semiconductor, cross-linkable binder polymer, and solvent in specific proportions. This composite formulation integrates multiple functional components into a single depositable material that provides both electronic function and structural stability
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 formation of well-defined, uniform interfaces between functional layers, reducing process steps and improving OLED performance, including extended device lifetime, while allowing for a wider range of material options without the need for solubility-modifying chemical means.
Implementation Method 1
the dissolution rate of the first organic functional material in the second solvent is less than 1e-05 g/(cm² s)
Implementation Method 2
the second solvent is an organic solvent having a boiling point in the range from 210 to 350°C at 1.01325 bar
Data Source
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AI summary
The present invention relates to a process for the preparation of an electronic device such as an organic electroluminescent device (OLED), wherein two adjacent functional layers having an interface are formed from solution in a kinetically controlled manner. The process is particularly suitable for fast and efficient production of electronic devices by printing or coating processes. The invention further relates to an electronic device which is obtainable by said process.