Micro LED Color Conversion via Graded Refractive Index Stacks
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Solution Overview
Problem
Micro LED displays face challenges in achieving high power efficiency and low manufacturing costs, particularly in depositing uniform quantum dot coatings for red and blue micro LEDs, which results in high power consumption and production costs due to inefficient methods like ink-jet printing, spin-coating, and slot-die processes.
Innovation Solution
The use of micro color conversion devices (CCDs) with a graded refractive index stack of quantum dot photoresist layers, optimized for maximum external quantum efficiency, and oxide-to-oxide bonding technology for transferring CCDs onto a display backplane, enabling efficient blue light conversion to red light and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ink-jet printing, spin-coating, or slot-die processes are used to deposit quantum dot coatings, then uniform coating can be achieved, but power consumption and production costs increase significantly
Solution Approach 1:
The patent extracts the quantum dot coating deposition from complex, energy-intensive processes (ink-jet printing, spin-coating, slot-die) and replaces it with a simpler transfer method using photoresist patterns and thermal reflow, eliminating the need for expensive equipment and reducing power consumption while maintaining uniform coating quality
Solution Approach 2:
The patent uses photoresist patterns as templates to copy the desired quantum dot arrangement, then transfers this pattern through thermal reflow to create uniform quantum dot coatings without requiring complex deposition equipment, thereby reducing both capital costs and operational power consumption
2Ease of manufacture
If conventional quantum dot deposition methods are used, then red and blue micro LEDs can be manufactured, but production costs become prohibitively high
Solution Approach 1:
The patent employs disposable photoresist patterns that are easily fabricated using standard photolithography, replacing expensive and complex deposition equipment. The photoresist serves as a temporary, low-cost template that enables precise quantum dot placement without requiring costly specialized machinery
Solution Approach 2:
The patent changes the deposition parameter from complex mechanical/chemical processes (ink-jet, spin-coating) to a simple thermal process (reflow at 150-200°C), dramatically reducing equipment costs and making the manufacturing process accessible to standard fabrication facilities
3Illumination intensity
If color conversion devices are added to micro LED displays, then color gamut is improved, but device complexity increases
Solution Approach 1:
The patent merges the color conversion function directly into the quantum dot layer that is already part of the micro LED structure. By integrating the quantum dots with the photoresist pattern during the same fabrication process, the patent adds color conversion capability without requiring separate, additional components or complex assembly steps
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 results in lower power consumption, improved color gamut, and reduced production costs, while overcoming the limitations of existing methods by enhancing quantum conversion efficiency and achieving uniform coatings for micro LED displays.
Implementation Method 1
efficient blue light conversion to red light
Implementation Method 2
oxide-to-oxide bonding technology for transferring CCDs onto a display backplane
Data Source
AI summary
Micro light-emitting diode displays and methods of fabricating micro LED displays are described. In an example, a micro light emitting diode pixel structure includes a plurality of micro light emitting diode devices in a dielectric layer. A transparent conducting oxide layer is above the dielectric layer. A color conversion device (CCD) is above the transparent conducting oxide layer and over one of the plurality of micro light emitting diode devices.