LED Pixel Array with Red Conversion for Efficient RGB Emission
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Solution Overview
Problem
Existing LED devices face challenges in efficiently emitting red light, particularly in the context of augmented reality light sources, due to inefficiencies in indium gallium nitride (InGaN) emission at long wavelengths.
Innovation Solution
The implementation of a red converting layer on top of a p-type layer in LED devices, which replaces the traditional red indium gallium nitride (InGaN) emitting region, allowing for efficient red light emission through a patternable light conversion layer such as quantum dot phosphors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional InGaN active region is used for red light emission, then the LED structure is simple, but the emission efficiency is poor
Solution Approach 1:
The patent introduces a red converting layer as an intermediary component between the blue LED active region and the output. This layer converts blue light to red light through photoluminescence, achieving efficient red light emission without requiring a separate red InGaN active region. The converting layer acts as a mediator that transforms the light wavelength while maintaining structural simplicity.
Solution Approach 2:
The patent changes the optical parameters by using a red converting layer with specific photoluminescence characteristics instead of attempting to improve red light emission through traditional InGaN material parameter optimization. This approach leverages the conversion efficiency of the red converting layer to achieve high red light emission efficiency.
2Adaptability or versatility
If three quantum well stack is used to enable full display gamut, then the color coverage is improved, but the manufacturing complexity increases substantially
Solution Approach 1:
The patent extracts the red light generation function from the traditional three-quantum-well InGaN structure and relocates it to a red converting layer. This separation allows the active region to focus on efficient blue light generation while the red converting layer handles red light production, simplifying the epitaxial growth process while maintaining full display gamut capability.
Solution Approach 2:
The red converting layer serves multiple functions: it converts blue light to red light, enables full display gamut coverage, and can be selectively patterned for different pixel configurations. This multi-functional approach replaces the need for separate red-emitting quantum wells while achieving the same display performance.
3Use of energy by moving object
If red converting layer is used instead of red InGaN active region, then the red light emission efficiency is improved, but the manufacturing process complexity increases
Solution Approach 1:
The red converting layer is integrated into the epitaxial structure during the initial growth process, allowing for preliminary positioning and alignment. This preliminary integration simplifies subsequent manufacturing steps by establishing the correct spatial relationships between components before device assembly and testing.
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 high-efficiency red light emission, surpassing conventional Red Green Blue conversion schemes with improved resolution and brightness, suitable for augmented reality applications.
Implementation Method 1
a red converting layer on a top surface of the p-contact layer
Data Source
AI summary
Provided is an LED (100) comprised of an epitaxial stack having two active regions (106a, 106b) separated by a tunnel junction (108). A red converting element (112) may be added selectively to pixels during device isolation/processing to create an array of pixels that can be controlled to be blue or green or a mix of the two, and other pixels that use the blue or green active regions to pump the red converting element (112) to stimulate red emission from this specific pixel area. An alternative can be during device processing to selectively remove the topmost active region (green or blue) and replace that with a red converting material. This could permit a coplanar final structure.