OLED Anode Work Function Gradient for Brightness Uniformity
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Solution Overview
Problem
The existing OLED display panels suffer from poorer brightness uniformity due to the 'coffee-ring effect' during the formation of the organic light-emitting layer, where the region close to the pixel defining layer is thicker and has lower brightness compared to the region away from it, leading to non-uniform light emission.
Innovation Solution
The OLED display panel design features a first electrode with a center sub-electrode and ring-shaped sub-electrodes arranged around it, where the work function increases sequentially from the center to the edge, ensuring more holes are injected into the thicker regions of the organic light-emitting layer, thereby correcting the brightness difference and improving uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inkjet printing is used to form the organic light-emitting layer in sub-pixel regions defined by the pixel defining layer, then the organic light-emitting layer can be formed, but the coffee-ring effect causes non-uniform thickness and poor brightness uniformity
Solution Approach 1:
The first electrode is designed with spatially varying work function characteristics: the peripheral portion has a higher work function while the middle portion has a lower work function. This local quality variation creates different hole injection characteristics in different regions, compensating for the thickness non-uniformity caused by the coffee-ring effect and achieving improved brightness uniformity across the sub-pixel region.
2Illumination intensity
If the organic light-emitting layer is formed by spraying material solution into the sub-pixel region, then the layer can be created, but the edge region becomes thicker and emits lower brightness compared to the center region
Solution Approach 1:
The work function parameter of the first electrode is changed spatially: the peripheral portion uses a higher work function material or structure, while the middle portion uses a lower work function material. This parameter change modifies the hole injection efficiency in different regions, with the peripheral portion injecting more holes to compensate for the thicker organic light-emitting layer, thereby achieving uniform brightness across the entire sub-pixel region.
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 design effectively enhances the brightness uniformity of the organic light-emitting layer by adjusting the number of holes injected into different regions, reducing the brightness difference between the edge and center regions, resulting in improved light emission uniformity.
Implementation Method 1
The existing OLED display panels suffer from poorer brightness uniformity due to the 'coffee-ring effect' during the formation of the organic light-emitting layer, where the region close to the pixel defining layer is thicker and has lower brightness compared to the region away from it
Data Source
AI summary
The present disclosure discloses an organic light-emitting diode display panel and a manufacturing method thereof and a display device, and relates to the field of display technologies. The organic light-emitting diode display panel comprises: a base substrate; a pixel defining layer and a plurality of first electrodes on the base substrate, wherein the pixel defining layer defines, on the base substrate, a plurality of sub-pixel regions arranged in an array, one of the first electrodes is located in each of the sub-pixel regions, and the work function of a middle portion of the first electrode is less than the work function of a peripheral portion; an organic light-emitting layer on each of the first electrodes; and a second electrode electrically connected to the organic light-emitting layer, wherein the first electrode is an anode and the second electrode is a cathode.