Soluble Electron Transport Ink for OLEDs
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Solution Overview
Problem
Large-size OLED products face challenges with warpage, deformation, and high material waste due to complex equipment and processes, and the full-printing process for OLED devices is hindered by the miscibility of organic solvent-dissolved electron transport layer materials with the light emitting layer, as well as damage to lower layers during cathode formation.
Innovation Solution
The use of a soluble organic electron transport material configured as an ink with a polar mixed solvent, specifically a polyol-based solvent, allows for the formation of an electron transport layer by printing without damaging the light emitting layer, enabling device performance comparable to vapor-deposited layers and reducing material and process costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum evaporation process is used for electron transport layer, then device performance is improved, but material cost and process complexity increase
Solution Approach 1:
The patent replaces the vacuum evaporation mechanical system with a solution processing system. The electron transport layer is formed by coating a solution containing electron transport material onto the substrate, allowing the layer to dry and form a functional film. This substitution eliminates complex vacuum equipment while achieving comparable device performance through chemical solution deposition.
Solution Approach 2:
The patent changes the physical state of the electron transport material from vapor phase (vacuum evaporation) to solution phase (liquid coating). By dissolving the electron transport material in a suitable solvent and controlling the coating and drying parameters, the patent achieves the desired layer formation without requiring vacuum conditions, thereby simplifying the process while maintaining performance.
2Ease of manufacture
If organic solvent-dissolved electron transport material is used, then printing process is enabled, but light emitting layer is damaged due to miscibility
Solution Approach 1:
The patent introduces a carefully selected solvent as an intermediary that enables the electron transport material to be dissolved and printed without causing damage to the light emitting layer. The solvent is chosen to have appropriate solubility characteristics that allow controlled deposition and rapid evaporation, preventing excessive interaction with the underlying light emitting layer while still enabling complete coverage and uniform film formation.
Solution Approach 2:
The patent applies different quality requirements to different regions and stages of the process. The solvent is selected to have specific solubility parameters that match the electron transport material while being incompatible with the light emitting layer materials. This localized chemical compatibility ensures that the printed electron transport layer achieves proper adhesion and functionality without damaging the underlying sensitive layers.
3Area of stationary object
If large-size reticle is used for OLED fabrication, then large-size display is achieved, but warpage and deformation increase
Solution Approach 1:
The patent replaces the mechanical reticle-based patterning system with a direct solution processing approach. Instead of using large reticles that cause warpage and alignment issues, the electron transport layer material is dissolved in a solvent and directly coated onto the substrate. This eliminates the mechanical constraints of reticle handling and allows for large-area uniform deposition without the associated warpage and deformation problems.
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 preparation of high-performance OLED devices with reduced material and process costs by using a printable ink for the electron transport layer, achieving performance equivalent to vapor-deposited layers while avoiding solvent-induced damage.
Implementation Method 1
An ink is configurable by a specific solvent. Since the specific solvent used is a polar mixed solvent containing a polyol
Data Source
AI summary
An organic light emitting diode display device and a method of fabricating same are provided. The organic light emitting diode display includes an electron transport layer disposed on a light emitting layer, and material of the electron transport layer comprises a soluble organic electron transport material. The electron transport layer can be formed by ink and by inkjet printing.