All-Inorganic Up-Conversion Display With Flip-Chip Photodiode-LED Arrays
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Solution Overview
Problem
Current up-conversion elements, particularly all-inorganic types, face challenges such as lattice mismatch issues, low photoelectric conversion efficiency, and high driving voltage, limiting their application in large-scale manufacturing and practical use in fields like night displays and biomedical imaging.
Innovation Solution
An all-inorganic up-conversion display is developed, comprising a photodiode array and a light emitting diode array with flip-chip bonding of solder bumps, utilizing inorganic semiconductor materials to avoid lattice mismatch and reduce driving voltage, while achieving high photocurrent and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If wafer fusion bonding is used to manufacture all-inorganic up-conversion elements, then photoelectric conversion efficiency is improved, but manufacturing size is limited to 1mm×1mm and yield is low
Solution Approach 1:
The patent divides the up-conversion element into separate photodiode and LED modules that can be manufactured independently and then integrated. This segmentation allows each component to be optimized separately and enables large-scale production through modular assembly, resolving the contradiction between maintaining high photoelectric conversion efficiency and achieving large manufacturing yield and size.
Solution Approach 2:
The patent introduces an organic encapsulation layer as an intermediary between the inorganic photodiode and LED components. This intermediary enables reliable integration of disparate materials while maintaining the high efficiency of inorganic semiconductors, allowing both high photoelectric conversion and scalable manufacturing through standardized module assembly.
2Area of stationary object
If organic up-conversion elements are used, then large area non-pixel display is achieved, but light conversion efficiency from infrared to visible light is low and high bias voltage is required
Solution Approach 1:
The patent applies local quality by using inorganic materials with superior photoelectric properties in the critical light conversion regions (photodiode and LED active layers), while using organic materials only for encapsulation and interconnection. This localized application of material properties achieves high conversion efficiency where needed while maintaining large display area capability.
Solution Approach 2:
The patent creates a hybrid composite structure combining inorganic semiconductor components (for high efficiency light conversion) with organic encapsulation and interconnection materials. This composite approach leverages the advantages of both material systems: the high efficiency of inorganic semiconductors and the flexibility/large-area capability of organic materials.
3Ease of manufacture
If inorganic photodiode and LED are epitaxially grown on the same substrate, then integration is achieved, but lattice match requirement limits material selection and composition ratios
Solution Approach 1:
The patent segments the device into separately manufactured photodiode and LED modules that are subsequently integrated through bonding and encapsulation. This approach eliminates the need for epitaxial growth on the same substrate, thereby removing lattice matching constraints while maintaining effective integration. Each module can use optimal material compositions independent of the other.
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
The solution results in a high-efficiency up-conversion display with a low driving voltage and MHz-level light-to-light frequency response, enhancing photocurrent, photoresponsivity, and power efficiency, suitable for various applications including night vision and imaging systems.
Implementation Method 1
a photodiode array and a light emitting diode array... an absorption layer formed on the buffer layer
Implementation Method 2
a light emitting diode array... an array of luminous chips... each of the luminous chips includes a first semiconductor layer... a second semiconductor layer... an active layer
Data Source
AI summary
An all-inorganic up-conversion display includes a photodiode array and a light emitting diode array. The photodiode array includes a first substrate having a first conductivity type, a buffer layer formed on a first surface of the first substrate, an absorption layer formed on the buffer layer, a cap layer formed on the absorption layer, a first patterned passivation layer formed on the cap layer and exposing an array of contact regions of the cap layer, a common first electrode connected to the first substrate, an array of second electrodes, and an array of first solder bumps. The light emitting array includes a second substrate, an array of luminous chips, a common third electrode, a second patterned passivation layer, and an array of second solder bumps. Each of the first solder bumps is flip-chip bonded to a corresponding one of the second solder bumps.