Stacked Light-Emitting Element Optical Path Optimization
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Solution Overview
Problem
The existing methods for manufacturing electroluminescent (EL) display devices face challenges in increasing yield and productivity due to shape defects and emission defects caused by metal mask contact during the selective deposition of light-emitting materials, and they struggle to achieve high-definition displays with high color purity and low power consumption.
Innovation Solution
A light-emitting element structure is proposed, comprising an electrode with reflective properties, a first light-emitting layer, a charge generation layer, and a second light-emitting layer with a conductive electrode having a light-transmitting property, where the optical path lengths between the reflective electrode and each light-emitting layer are optimized to align the phases of entering and reflected light, enhancing luminance and allowing for continuous film formation without selective deposition using a metal mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selective deposition of light-emitting materials is performed using a metal mask, then light-emitting elements can be manufactured with color differentiation, but shape defects and emission defects occur due to contact between the metal mask and pixel electrode
Solution Approach 1:
The invention extracts and removes the metal mask from the manufacturing process entirely. Instead of using selective deposition with a metal mask, the patent employs a common continuous film formation process without any mask, thereby eliminating the source of shape defects and emission defects caused by mask contact with the pixel electrode.
Solution Approach 2:
The invention changes the deposition parameters by forming continuous films at different potentials rather than performing selective deposition. By controlling the electrochemical potential during film formation, different light-emitting materials are deposited in different regions without requiring a physical mask, thus avoiding mask-related defects while maintaining manufacturing precision.
2Manufacturing precision
If selective deposition is performed for each pixel, then light-emitting materials can be precisely deposited, but the process becomes complicated and productivity decreases
Solution Approach 1:
The invention merges multiple selective deposition steps into a single continuous film formation process. By applying different potentials to different regions simultaneously during one deposition cycle, multiple light-emitting materials are deposited in their respective regions without requiring separate processing steps for each pixel, thereby maintaining precision while dramatically improving productivity.
Solution Approach 2:
The invention replaces the mechanical metal mask system with an electrochemical potential control system. Instead of using physical masks to define deposition regions, the patent uses potential distribution during electrochemical film formation to control where materials are deposited, simplifying the process and enabling continuous film formation without mask-related complications.
3Ease of manufacture
If conventional light-emitting element structure is used, then manufacturing is straightforward, but luminance is insufficient and power consumption is high
Solution Approach 1:
The invention introduces a third dimension by stacking multiple light-emitting layers vertically within the same pixel structure. Instead of relying on a single light-emitting layer, the patent forms multiple layers at different potentials, allowing light to be emitted from multiple depths, thereby significantly increasing overall luminance while maintaining ease of manufacture through continuous film formation.
Solution Approach 2:
The invention uses composite light-emitting layer structures with different materials deposited in specific regions. By forming continuous films of different light-emitting materials at different potentials and stacking them vertically, the patent creates a composite structure that enhances luminance through multiple emission sources while maintaining manufacturing simplicity.
4Productivity
If continuous film formation without metal mask is used, then productivity and yield are improved, but selective deposition precision must be maintained
Solution Approach 1:
The invention uses potential as a controlling parameter to achieve selective deposition during continuous film formation. By applying different electrochemical potentials to different regions simultaneously, the patent controls which light-emitting materials are deposited where, maintaining manufacturing precision without requiring a metal mask, thereby enabling high productivity and yield.
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 structure increases the luminance of the light-emitting elements, enables high-definition displays with high color purity, and reduces power consumption by optimizing the optical path lengths and allowing for continuous film formation, thereby improving productivity and yield.
Implementation Method 1
The optical path length between the electrode having a reflective property and the first light-emitting layer is one-quarter of the peak wavelength of the emission spectrum of the first light-emitting layer. The optical path length between the electrode having a reflective property and the second light-emitting layer is three-quarters of the peak wavelength of the emission spectrum of the second light-emitting layer.
Data Source
AI summary
A light-emitting element with which a reduction in power consumption and an improvement in productivity of a display device can be achieved is provided. A technique of manufacturing a display device with high productivity is provided. The light-emitting element includes an electrode having a reflective property, and a first light-emitting layer, a charge generation layer, a second light-emitting layer, and an electrode having a light-transmitting property stacked in this order over the electrode having a reflective property. The optical path length between the electrode having a reflective property and the first light-emitting layer is one-quarter of the peak wavelength of the emission spectrum of the first light-emitting layer. The optical path length between the electrode having a reflective property and the second light-emitting layer is three-quarters of the peak wavelength of the emission spectrum of the second light-emitting layer.