Organic Light Emitting Display With Patterned Hole Injection Layer
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Solution Overview
Problem
Existing organic light emitting displays face challenges in achieving improved color purity and efficiency due to the need for varying optical thicknesses of organic thin films across differently colored pixels, while also requiring a cost-effective and simplified manufacturing process.
Innovation Solution
The solution involves an organic light emitting display structure with a hole injection layer of varying thicknesses for red, green, and blue pixels, where the hole injection layer is patterned separately for each color, and a method of fabrication that includes forming a hole injection layer with different thicknesses using techniques like laser-induced thermal imaging or vacuum evaporation, followed by a hole transport layer, white light emitting layer, electron transport layer, electron injection layer, and a color filter to enhance light emission efficiency and chromatic purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the organic thin film thickness is varied for each pixel to improve color purity, then color purity is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality by varying the thickness of the hole injection layer specifically in the red pixel region compared to green and blue pixels. The red pixel region has a thicker hole injection layer (50-100 nm) while green and blue pixels have a standard thickness (20-50 nm), allowing optimization of color purity for each pixel type without complicating the entire manufacturing process
Solution Approach 2:
The patent changes the physical parameter of layer thickness to improve color purity. By adjusting the thickness of the hole injection layer in red pixels to be greater than in green and blue pixels, the optical path difference compensates for the broader emission spectrum of red pixels, thereby improving color purity while maintaining a relatively simple manufacturing process
2Productivity
If separate patterning is performed for each pixel color to optimize thickness, then color efficiency is improved, but the number of manufacturing steps increases
Solution Approach 1:
The patent implements local quality by applying different hole injection layer thicknesses only where needed - specifically in the red pixel regions - while using a uniform thickness for green and blue pixels. This selective approach optimizes light emission efficiency for red pixels without requiring separate patterning for all three colors, thereby reducing the total number of manufacturing steps
Solution Approach 2:
The patent segments the hole injection layer formation process into two parts: a base layer formed uniformly across all pixels, and an additional layer formed only in red pixel regions. This segmentation allows optimization of red pixel efficiency while avoiding the need for complete separate patterning of all pixel types, thus reducing manufacturing complexity
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 improves color purity and efficiency by optimizing light emission for each pixel through varying thicknesses and simplifies the manufacturing process by reducing the number of patterning steps, resulting in a more cost-effective and efficient organic light emitting display.
Implementation Method 1
a first hole injection layer entirely covering the first electrodes arranged on the substrate and a patterned second hole injection layer arranged on the first hole injection layer and arranged separately over ones of the plurality of pixels
Implementation Method 2
forming a hole injection layer with different thicknesses using techniques like laser-induced thermal imaging
Implementation Method 3
forming a hole injection layer with different thicknesses using techniques like laser-induced thermal imaging or vacuum evaporation
Implementation Method 4
electrons and holes are injected into organic materials from an anode and a cathode and are recombined to generate excitons, and a specific wavelength of light is generated by energy generated from the excitons
Data Source
AI summary
An organic light emitting display that includes a substrate, a plurality of first electrodes arranged in a corresponding plurality of pixels, the plurality of pixels including red pixels, blue pixels and green pixels, a hole injection layer arranged on the first electrodes arranged on the substrate, the hole injection layer having different respective thicknesses in correspondence with the pixels, a hole transport layer entirely covering the hole injection layer, a white light emitting layer entirely covering the hole transport layer, an electron transport layer arranged on the white light emitting layer, a second electrode arranged on the electron transport layer and a color filter arranged on the second electrode.