EL Display Light-Emitting Layer Peripheral Protrusion Bank Interface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic EL light-emitting element manufacturing methods using large substrates face challenges in maintaining consistent luminance efficiency across sub-pixels due to variations in film thickness, particularly when the light-emitting layer is thin at the interface with the bank, leading to reduced light emission efficiency.
Innovation Solution
The implementation of a light-emitting layer structure with a peripheral protrusion that contacts the bank, where the peripheral protrusion's thickness is at least 20% of the main portion's thickness, prevents excess current flow and maintains consistent light emission efficiency by ensuring the film thickness is not excessively thin at the interface with the bank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If coating methods (inkjet printing, screen printing, gravure printing) are used to form organic EL light-emitting elements on large substrates, then large screen manufacturing and cost reduction are achieved, but variation in film thickness occurs leading to inconsistent luminance efficiency across sub-pixels
Solution Approach 1:
The patent applies local quality by creating a peripheral protrusion structure specifically at the interface region between the light-emitting layer and the bank. This protrusion has a greater thickness than the main body of the light-emitting layer, providing localized compensation for thickness variations that occur during coating processes. The protrusion structure ensures that the light-emitting layer maintains adequate thickness at the critical interface area where thickness variation most affects luminance efficiency, while the rest of the layer can be optimized for other performance parameters.
2Length of moving object
If the light-emitting layer is made thin to reduce device thickness and improve responsiveness, then device performance is enhanced, but light emission efficiency decreases due to excess current flow at the bank interface
Solution Approach 1:
The patent implements local quality by creating a peripheral protrusion with increased thickness specifically at the bank interface region. This localized thickening compensates for the overall thin design of the light-emitting layer. The protrusion structure ensures that at the critical interface area where current density is highest and thickness variation has the greatest impact on efficiency, the layer maintains sufficient thickness to prevent excess current flow and maintain high light emission efficiency, while the rest of the layer remains thin for overall device performance.
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 configuration effectively suppresses the reduction in light emission efficiency by preventing excess current flow through the peripheral protrusions, maintaining high definition and luminance consistency across sub-pixels.
Implementation Method 1
EL display devices that have a first electrode, a plurality of organic layers including a light-emitting layer, and a second electrode layered in order on a driving substrate are attracting attention. EL display devices have features such as self-generated light emission
Data Source
AI summary
An EL display device including a light emitter configured to emit at least red, green, and blue light; and a thin film transistor array that controls light emission. The light emitter includes light-emitting layers within areas defined by a bank that emit at least red, green, and blue light. The light emitter further includes electrodes that extend under the bank and hole transport layers that are above the electrodes within the areas defined by the bank, the light-emitting layers being formed on the hole transport layers. The hole transport layers each have a main portion and a peripheral protrusion in contact with a side surface of the bank that protrudes upwards from the main portion. The light-emitting layers each have a peripheral protrusion in contact with a side surface of the bank, formed above a corresponding one of the peripheral protrusions.