IR Up-conversion Device with CMOS Sensor for Night Vision
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Solution Overview
Problem
Current up-conversion devices, particularly those based on inorganic and hybrid semiconductor structures, face low conversion efficiencies and high fabrication costs, making them unsuitable for practical applications such as night vision and semiconductor wafer inspections, and lack an infrared sensitizing layer with a broad absorption spectrum.
Innovation Solution
A transparent infrared-to-visible up-conversion device with a multilayer stack structure incorporating a CMOS image sensor, featuring a polydispersed quantum dot IR sensitizing layer, hole blocking, transport, and light-emitting layers, along with an antireflective and IR pass visible blocking layers, to enhance signal amplification and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic or hybrid semiconductor structures are used for up-conversion devices, then the device structure is well-defined and functional, but the conversion efficiency remains very low (0.048-0.7% W/W) and fabrication cost is high
Solution Approach 1:
The patent employs a composite structure combining organic materials (OLED layer, hole transport layers, electron transport layers) with inorganic materials (quantum dot IR sensitizing layer, ITO anode, Al cathode). This hybrid composite approach enables the device to achieve both low-cost fabrication through solution-processing of organic layers and high conversion efficiency through the quantum dot's superior optical properties, directly resolving the contradiction between manufacturing ease and conversion efficiency
Solution Approach 2:
The patent changes the material parameters by replacing traditional inorganic photodetectors with organic OLED materials that can be processed at lower costs, while maintaining or improving conversion efficiency through optimized layer thicknesses, material compositions, and quantum dot size distributions. The use of polydispersed quantum dots with specific size ranges (2-10 nm) transforms the absorption characteristics to achieve broad-spectrum IR sensitivity
2Adaptability or versatility
If traditional up-conversion devices are used, then the device structure is simple, but the absorption spectrum is narrow and lacks broad IR sensitivity
Solution Approach 1:
The patent segments the functional requirements into distinct layers: the quantum dot IR sensitizing layer handles broad-spectrum IR absorption, while separate organic layers (hole transport, electron transport, OLED) handle charge transport and light emission. This segmentation allows each layer to be optimized independently for its specific function, achieving broad absorption spectrum without overwhelming complexity
Solution Approach 2:
The quantum dot IR sensitizing layer serves multiple functions simultaneously: it absorbs IR radiation across a broad spectrum, generates excitons, and transfers energy to the OLED layer. This multi-functionality reduces the need for additional specialized components, achieving broad spectral coverage while managing device complexity
3Power
If signal amplification is achieved through additional illuminating sources, then the signal strength increases, but the device complexity and power consumption increase
Solution Approach 1:
The up-conversion device is self-powered through the electroluminescence of the OLED layer, which is driven by electrical current without requiring external illuminating sources. The device converts electrical energy directly into visible light that amplifies the IR signal, achieving signal amplification while eliminating the need for additional power-consuming illumination systems
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 achieves improved photon-to-photon conversion efficiency and enables effective infrared signal detection and amplification, even under low-intensity IR irradiation, suitable for night vision applications without the need for additional illuminating sources.
Implementation Method 1
the IR sensitizing layer comprises polydispersed quantum dots (QDs)
Implementation Method 2
a transparent infrared (IR) to visible up-conversion device
Implementation Method 3
a light emitting layer (LED)
Implementation Method 4
a CMOS image sensor (CIS)
Data Source
Figure 1~2
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AI summary
Imaging devices include an IR up-conversion device on a CMOS imaging sensor (CIS) where the up-conversion device comprises a transparent multilayer stack. The multilayer stack includes an IR sensitizing layer and a light emitting layer situated between a transparent anode and a transparent cathode. In embodiments of the invention, the multilayer stack is formed on a transparent support that is coupled to the CIS by a mechanical fastener or an adhesive or by lamination. In another embodiment of the invention, the CIS functions as a supporting substrate for formation of the multilayer stack.