Printed Light Modifier Structures for Emissive Displays
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Solution Overview
Problem
Conventional emissive display fabrication processes require separate substrates for light and color modification, adding complexity and expense, and struggle to confine color modification materials to specific sub-pixels without spreading.
Innovation Solution
A method for directly printing light modifier structures, such as quantum dots and phosphors, over micro-size light emitting diode pixels within substrate wells, using inkjet printing to confine the materials and prevent spreading, allowing for efficient color conversion and scattering of light within the emissive substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate substrates are used for light and color modification, then color conversion can be achieved, but device complexity and fabrication expense increase
Solution Approach 1:
The patent combines the light modification layer and color conversion layer into a single integrated substrate, eliminating the need for separate substrates. The light modification material (e.g., TiO2 nanoparticles) and color conversion material (e.g., quantum dots or phosphors) are deposited together in one layer structure, simplifying the device architecture while maintaining color conversion functionality.
Solution Approach 2:
The single substrate performs multiple functions simultaneously: it provides structural support, modifies light properties through scattering or extraction, and converts colors via phosphors or quantum dots. This multi-functional integration eliminates the need for separate specialized substrates for each function.
2Reliability
If conventional processing is used to form color modification layers, then color conversion is achieved, but material spreading occurs between adjacent sub-pixels
Solution Approach 1:
The substrate surface is divided into discrete wells or recessed regions, each containing an emissive element. The light modification material is deposited within these segmented regions, physically confining the material to specific sub-pixel areas and preventing spreading into adjacent regions. This segmentation approach maintains sharp boundaries between different color sub-pixels.
Solution Approach 2:
The light modification and color conversion materials are applied locally to specific regions corresponding to individual sub-pixels rather than as uniform layers. This localized application ensures that each sub-pixel receives the appropriate materials without contamination from adjacent sub-pixels, maintaining color purity and precision.
3Manufacturing precision
If direct printing of light modifier structures is used, then material confinement to specific sub-pixels is improved, but new fabrication challenges arise
Solution Approach 1:
The patent employs inkjet printing technology to deposit light modification and color conversion materials. This hydraulic/pneumatic-based printing method allows precise digital control of material placement, enabling direct writing of patterns with high resolution and minimal material waste, while maintaining ease of manufacture through a relatively simple single-step process.
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 enables the creation of high-definition multi-color emissive displays with improved color gamut and efficiency, eliminating the need for separate substrates and preventing light modifier material from interfering with adjacent sub-pixels.
Implementation Method 1
color conversion elements to down-convert some portion of the blue emitting LED subpixels to red and green subpixels. This can be done with phosphors or quantum dots
Implementation Method 2
even LEDs with no overlying color modifier typically require a light diffuser layer to randomize the distribution of light
Data Source
AI summary
A multi-color emissive display is presented with printed light modifier structures. A fabrication method provides an emissive substrate with a plurality of wells formed in the emissions substrate top surface, and a plurality of emissive elements populating the wells. The method prints light modifier structures overlying the emissive elements. Some examples of light modifier material include light scattering materials, phosphors, and quantum dots. In one aspect, the emissive substrate wells have a first shape, with sidewalls and a first perimeter. Likewise, the emissive elements have the first shape, with sides and a second perimeter, less than the first perimeter. The light modifier structures fill the space between the emissive element sides and the well sidewalls with light modifier material. If the first shape is circular, the method prints the light modifier structures overlying the emissive elements in the circular shape having a first diameter defined by the well sidewalls.