Stacked Small and Large Molecular Layers for OLED Film Formation
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Solution Overview
Problem
The formation of display panels with stacked films is hindered by the increased viscosity and reduced volatilization rate of solutions containing large molecules, making it difficult to form target films and subsequently the electroluminescent devices.
Innovation Solution
The use of a target film comprising a stacked arrangement of small and large molecular layers, where the small molecular layer has a larger thickness than the large molecular layer, and the hole transport layer and electron transport layer have specific energy levels and cross-linked network structures, facilitating easier formation through the solution process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solution containing large molecules is used to form the target film, then the target film can be formed by solution process, but the viscosity increases and volatilization rate decreases making it difficult to form the film
Solution Approach 1:
The target film is segmented into a stacked structure comprising multiple small molecular layers and multiple large molecular layers. This segmentation allows the large molecular layers to be distributed among smaller units, reducing the overall viscosity of the solution while maintaining the presence of large molecules necessary for film formation.
Solution Approach 2:
The target film uses a composite structure combining small molecular layers and large molecular layers in a stacked arrangement. This composite approach leverages the advantages of both small molecules (lower viscosity, easier processing) and large molecules (film-forming capability), achieving a balance between ease of manufacture and solution properties.
2Ease of manufacture
If a solution containing large molecules is used to form the target film, then the target film can be formed by solution process, but the volatilization rate decreases making it difficult to form the film
Solution Approach 1:
By dividing the large molecular content into multiple smaller layers within the stacked structure, the solution can be processed in smaller increments. This segmentation facilitates faster volatilization of the solvent in each layer, overcoming the reduced volatilization rate that would occur with a single large molecular layer.
Solution Approach 2:
The small molecular layers are positioned adjacent to and in alternation with the large molecular layers, creating a structure where the small molecules facilitate preliminary solvent evaporation. This preliminary action by the small molecular layers accelerates the overall volatilization process before the large molecular layers complete the film formation.
3Ease of manufacture
If the target film is formed by stacking small and large molecular layers, then the difficulty in forming the large molecular layer is reduced, but the device complexity increases
Solution Approach 1:
The small molecular layers and large molecular layers are merged into a single integrated target film structure through alternating stacking. This merging approach combines the ease of processing small molecules with the film-forming capabilities of large molecules, reducing the overall difficulty of formation while the regular alternating pattern prevents excessive complexity.
Solution Approach 2:
Different regions of the target film have localized qualities: small molecular layers provide regions of low viscosity and fast volatilization, while large molecular layers provide regions of high film-forming capability. This local differentiation allows each layer to perform its specific function optimally, reducing the difficulty of forming the large molecular layers without requiring complex overall device architecture.
Data Source
AI summary
An electroluminescent device, a method for fabricating the same, a display panel, and a display device are disclosed. The electroluminescent device includes a hole inject layer, a hole transport layer, an electron transport layer, and an electron inject layer. At least one of the hole inject layer, the hole transport layer, the electron transport layer, and electron inject layer is a target film including a small molecular layer and a large molecular layer which are arranged in a stacked manner.