Abstract
Short-wave infrared (SWIR) imaging technology has broad application prospects in industry, medicine, and consumer electronics. However, traditional detectors such as indium gallium arsenide (InGaAs) are limited by high cost, limited spectral response range, and the difficulty in balancing high resolution and miniaturization, hindering their large-scale application. Colloidal quantum dots, a class of solution-processable low-dimensional semiconductor nanomaterials, possess unique quantum confinement effects that enable precise spectral tuning in the 1.0–3.0 μm wavelength range. They exhibit good compatibility with complementary metal-oxide-semiconductor (CMOS) processes and flexible substrates, opening a new path for the development of low-cost, high-performance SWIR detection technology. This paper systematically reviews the working principle, performance parameters, and latest research progress of quantum dot SWIR detectors both domestically and internationally. It focuses on their application potential in areas such as material defect detection, semiconductor monitoring, agricultural and food analysis, biomedical imaging, and mobile device integration, and also provides an outlook on future technological development and industrialization challenges.
Introduction
SWIR light typically refers to electromagnetic waves in the 1000–3000 nm spectral range. Its photon energy is lower than that of visible light, and it possesses several unique physical and application characteristics. For example, it can penetrate fog, smoke, rain, snow, and other harsh weather conditions, enabling all-weather visual enhancement; the 1550 nm band is widely recognized as a safe band for the human eye, supporting higher-power lighting applications; it can be selectively absorbed by water, sugar, and other substances, laying the foundation for accurate substance identification; simultaneously, SWIR light is transparent to silicon materials and organic light-emitting diode screens, giving it a natural advantage in under-display biometrics and semiconductor testing.
In the field of SWIR detection, indium gallium arsenide (InGaAs) detectors are the current mainstream technology. They are usually fabricated using indium phosphide (InP) as a substrate, and InGaAs epitaxial layers are grown by molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD) processes, thereby constructing PIN junction or Schottky junction device structures [1]. Such detectors have high quantum efficiency (peak band greater than 70%, high-performance devices can reach more than 85%) , fast response speed (rise time less than 10 ns, suitable for high frequency signal detection scenarios) , and low dark current. They have been widely used in high-precision spectral analysis, laser communication and other fields [1-3].
However, the widespread adoption of InGaAs detectors still faces many challenges: First, the material and fabrication costs remain high. The market price of 2-inch InP substrates is about 
2, 000 to 5, 000 per piece, which is 50 to 100 times that of silicon substrates of the same size (about 20 to 50 per piece) ; and the purchase cost (a single unit costs more than 10 million) and maintenance costs of MBE/MOCVD equipment are extremely high, resulting in the fabrication cost of a single InGaAs detector chip reaching tens of thousands of yuan, and the price of a complete imaging system such as a 640×512 area array camera is even higher, reaching hundreds of thousands of yuan [4]. Second, the spectral response range is limited. The cutoff wavelength of In0.53Ga0.47As under conventional composition is about 1.7 μm. If the response wavelength is to be extended to 2.0–2.6 μm, The In content needs to be increased, but the difference in atomic radius between In and Ga will cause significant lattice mismatch between the InGaAs epitaxial layer and the InP substrate (when the In content is increased from 53% to 80%, the mismatch increases from 0.6% to 3.2%) . This mismatch will cause a large number of dislocation defects in the epitaxial layer, resulting in a significant increase in dark current density, which cannot meet the requirements of low noise detection [5-6]. Third, the fabrication process is complex and mass production is difficult. InGaAs detectors need to be fabricated in an ultra-high vacuum environment (vacuum degree less than 10-8 Pa) and with precise temperature control (epitaxy temperature fluctuation less than 1℃) . The process window is narrow, and the mass production yield is usually less than 70%, which is difficult to match the production capacity requirements of large-scale applications [7]. In addition, due to the constraints of large-scale flip-chip bonding technology, InGaAs detectors are difficult to balance high resolution and miniaturization, and cannot meet the requirements of miniaturization and high integration for consumer electronics, wearable devices, etc. [8].
2, 000 to 5, 000 per piece, which is 50 to 100 times that of silicon substrates of the same size (about 20 to 50 per piece) ; and the purchase cost (a single unit costs more than 10 million) and maintenance costs of MBE/MOCVD equipment are extremely high, resulting in the fabrication cost of a single InGaAs detector chip reaching tens of thousands of yuan, and the price of a complete imaging system such as a 640×512 area array camera is even higher, reaching hundreds of thousands of yuan [4]. Second, the spectral response range is limited. The cutoff wavelength of In0.53Ga0.47As under conventional composition is about 1.7 μm. If the response wavelength is to be extended to 2.0–2.6 μm, The In content needs to be increased, but the difference in atomic radius between In and Ga will cause significant lattice mismatch between the InGaAs epitaxial layer and the InP substrate (when the In content is increased from 53% to 80%, the mismatch increases from 0.6% to 3.2%) . This mismatch will cause a large number of dislocation defects in the epitaxial layer, resulting in a significant increase in dark current density, which cannot meet the requirements of low noise detection [5-6]. Third, the fabrication process is complex and mass production is difficult. InGaAs detectors need to be fabricated in an ultra-high vacuum environment (vacuum degree less than 10-8 Pa) and with precise temperature control (epitaxy temperature fluctuation less than 1℃) . The process window is narrow, and the mass production yield is usually less than 70%, which is difficult to match the production capacity requirements of large-scale applications [7]. In addition, due to the constraints of large-scale flip-chip bonding technology, InGaAs detectors are difficult to balance high resolution and miniaturization, and cannot meet the requirements of miniaturization and high integration for consumer electronics, wearable devices, etc. [8].
In the field of SWIR detection, silicon-germanium (SiGe) detectors have a significant advantage in cost control due to their natural compatibility with silicon-based CMOS processes [9]. However, their performance is constrained by the inherent physical properties of the material, and there are two major limitations: First, lattice mismatch leads to high dark current. Since the lattice mismatch between silicon and germanium is about 4.2%, when growing SiGe layers on silicon substrates, it is easy to introduce high-density dislocation defects (usually the dislocation density exceeds 10⁶) . These defects become carrier recombination centers, leading to a significant increase in the dark current density of the device (up to 1–10 μA/cm² at –1 V bias) , which is much higher than the room temperature level of InGaAs detectors, thus severely degrading the noise performance and detection sensitivity of the device [10-12]. Second, the bandgap characteristics limit the spectral response range. The bandgap energy range of SiGe material is 0.66–0.80 eV, corresponding to a response wavelength of 1.55–1.88 μm. Even with optimization through strain engineering or multilayer heterostructure design, its cutoff wavelength is usually difficult to break through 1.7 μm, which cannot cover the core long-wave region of the SWIR band (2.0–3.0 μm) , thus limiting the application potential of this technology in deep tissue imaging, long-wave spectral analysis and other scenarios [13].
In recent years, quantum dots, as a new type of low-dimensional semiconductor nanomaterial, have achieved significant breakthroughs in both improving SWIR detection performance and reducing costs due to their unique quantum confinement effect, providing a new path for the industrialization of SWIR detection technology [14]. This article systematically reviews the working principle, material system, device structure, research progress and application scenarios of quantum dot SWIR detectors, deeply analyzes the current bottlenecks and challenges in technological development, and looks forward to future development directions. This has important academic value and practical significance for promoting academic research in this field, accelerating the process of technological industrialization, and expanding application boundaries.
1 Principles and Progress of Quantum Dot Shortwave Infrared Imaging Technology
Colloidal quantum dots are semiconductor nanocrystals with sizes ranging from 1 nm to 10 nm. When the crystal particle size is smaller than the Bohr exciton radius of its bulk material, electrons and holes are subjected to quantum confinement in three-dimensional space, causing the originally continuous band structure to split into discrete energy levels, and the band gap energy increases as the particle size decreases. This "size-band gap" modulation characteristic makes it possible to achieve a continuous spectral response in the1.0–3.0 μm band by changing the quantum dot particle size [15]. In addition, colloidal quantum dots can be processed by solution processing techniques such as spin coating, blade coating, inkjet printing [16] to form uniform thin films on various substrates such as silicon-based or flexible polymers. This characteristic makes it highly compatible with CMOS integrated circuit technology, providing an important foundation for the development of highly integrated, low-cost SWIR imaging chips [17].
1.1 Core Working Principle
1.1.1 Quantum confinement effect and spectral modulation mechanism
The quantum confinement effect is the core physical mechanism for realizing the short-wave infrared response of quantum dots. The essence of this effect lies in the relative relationship between the size of semiconductor nanocrystals and their Bohr exciton radius, which directly regulates the energy level structure of electrons and holes [18]. The Bohr exciton radius is a key parameter for measuring the intensity of electron-hole interaction in semiconductor materials, and its expression is:
(1)
In the formula, ε is the vacuum permittivity; ħ is the reduced Planck constant; µ is the reduced mass of the electron-hole pair; e is the electron charge [19]. When the quantum dot particle size d is less than twice the Bohr exciton radius 2a0, the movement of electrons and holes is strongly restricted in three-dimensional space, and the originally continuous energy band structure will split into discrete energy levels, which is called the strong quantum confinement effect; when the particle size is greater than 2a0, the quantum confinement effect is weaker, and the energy level structure tends to be close to that of bulk materials [20].
Size directly affects the absorption peak, band gap, and photoluminescence spectrum of quantum dot materials, thereby affecting the photoelectric performance and operating range of optoelectronic devices and photoelectric converters [21]. Weidman M C et al. [21] fitted the relationship between size and band gap based on experiments, and the specific expression is as follows:
(2)
In the formula, Eg represents electron volts (eV) ; the quantum dot diameter d represents nanometers (nm) ; and 0.41 is the bulk band gap of PbS. According to the relationship between photon energy and wavelength, E=hc/λ (h is Planck's constant, c is the speed of light) . By adjusting the particle size of quantum dots, their response wavelength λ can be precisely controlled, thus providing an important technical means for constructing a wide-band, customizable short-wave infrared detection system [22].
Fig.1: (a) Absorption spectra of PbS CQDs of different sizes synthesized in the range of 1000－1800 nm; (b) Relationship between band gap and size of PbS CQDs, where the dashed line is the best fit curve; (c) Photoluminescence spectra of 10 different sizes of PbS CQDs [23].
As shown in Figure1, taking lead sulfide (PbS) quantum dots as an example, the band gap energy of its bulk material is 0.41. eV (corresponding to a wavelength of 3.0 μm) . When the particle size increases from 2 nm to 8 nm, the band gap energy can be reduced from 1.03 eV (corresponding to a wavelength of 1.2 μm) to 0.50 eV (correspondilng to a wavelength of 2.5 μm) , which not only fully covers the main application range of the SWIR band, but also the spectral tuning accuracy can reach 5－10 nm particle size variation [23].
1.1.2 Working Mechanism and Performance Parameters of Quantum Dot Infrared Detector Devices
The core function of quantum dot SWIR detectors is to efficiently convert incident SWIR light signals into detectable electrical signals. Its working process is essentially a dynamic process of generation, separation, transport and collection of photogenerated carriers. Typical devices adopt a vertical stacked structure of "substrate－bottom electrode－functional layer－quantum dot active layer－top electrode". Among them, the functional layer usually contains an electron transport layer and a hole transport layer, which are used to regulate the direction of carrier transport and suppress reverse recombination [24]. Specifically, the device working process can be divided into the following four key stages.
The first stage is photon absorption and exciton generation. When SWIR light is incident perpendicularly on the device surface, most photons will penetrate the transparent top electrode and the functional layer and be absorbed by the quantum dot active layer. The absorption efficiency of quantum dots for photons depends on their light absorption cross section and film thickness [25]. Typically, the optical absorption cross section of SWIR quantum dots such as PbS and indium antimonide (InSb) in the1500 nm band is about 10⁻¹⁴ to 10⁻¹³ cm². To achieve an absorption efficiency of more than 90%, the thickness of the active layer needs to be controlled between 100 and 500 nm [26]. After the photon is absorbed, the electron in the valence band of the quantum dot absorbs energy and jumps to the conduction band, forming an electron-hole pair (i.e., exciton) . The exciton binding energy is usually 10 to 50 meV, which is higher than the room temperature thermal energy (about 26 meV) . Therefore, it is necessary to rely on an external electric field or the energy level difference at the heterojunction interface to achieve exciton separation [27].
The second stage is exciton separation. The driving force for exciton separation mainly comes from the energy level difference between the quantum dot and the functional layer [28]. Taking the contact between the quantum dot active layer and the titanium dioxide (TiO2) electron transport layer as an example: the conduction band bottom energy level of TiO2 (approximately －4.2 eV) lower than the conduction band bottom level of PbS quantum dots ( approximately －4.1 eV) . Its valence band top energy level is approximately －7.6 eV, while its valence band top energy level is approximately －7.6 eV. The energy level is higher than the valence band top level of PbS quantum dots (approximately －5.2 eV) . This energy level arrangement causes electrons in the excitons to migrate spontaneously to the TiO2 layer, while holes migrate to the hole transport layer, thereby achieving effective separation of excitons [29].
The third stage is carrier transport. After separation, electrons and holes need to be transported to the corresponding electrodes through the electron transport layer and hole transport layer, respectively. The efficiency of this process is mainly affected by the carrier mobility and the density of trapped states. The carrier mobility of quantum dot films is usually low, mainly because the ligands between quantum dots hinder carrier tunneling, and surface defects can form carrier traps [30].
The fourth stage is carrier collection. Carriers transported to the electrode interface are collected by the electrodes through ohmic contacts, forming a photocurrent. The electrode material must simultaneously meet the requirements of low contact resistance and high light transmittance (top electrode) .
The core parameters used to evaluate the performance of quantum dot SWIR detectors include dark current density, external quantum efficiency, response time, linear dynamic range, and specific detectivity. These parameters together determine the applicable scenarios and overall competitiveness of the device [31].
Dark current density Jdark refers to the current generated per unit area of a device under no-light conditions, mainly originating from thermally excited carriers, tunneling current, and leakage current caused by surface defect states. It is a key factor affecting the detector's noise level and its ability to detect weak signals. High-performance SWIR detectors typically have a dark current density of less than 1 μA/cm² at room temperature and －1 V bias, with some advanced devices reaching less than 100 nA/cm² [32]. The main source of dark current is surface defect states. For example, Pb²⁺ dangling bonds and S²⁻ vacancies on the surface of PbS quantum dots can form deep-level traps, leading to nonradiative recombination and leakage of charge carriers [33].
Responsivity R is a physical quantity (unit: A/W) that describes the photoelectric conversion capability of a device, that is, the ratio of the magnitude of the output electrical signal photoresponse current to the magnitude of the input optical signal power. It is a very important indicator that determines the performance of a photodetector [34], and can be expressed as
(3)
In the formula, Id is the photocurrent; Id is the dark current; P is the incident light power; and A is the effective illumination area. The responsivity is related to the material of the device, the incident light wavelength, and the illumination power density.
External quantum efficiency (EQE) is defined as the ratio of the number of photoelectrons collected by the detector to the number of incident photons, reflecting the overall efficiency of the device in converting photons into usable electrons. Its calculation formula is as follows:
(4)
In the formula, h is Planck's constant; c is the speed of light; J ph is the photocurrent density; q is the electron charge; λ is the incident light wavelength; and P is the incident light power density [35].
The response time τ includes the rise time (the time required for the photocurrent to rise from 10% to 90%) and the fall time ( the time required for the photocurrent to fall from 90% to 10%) , which is mainly affected by the exciton separation rate, carrier transport time, and trap state lifetime [36].
Linear Dynamic Range (LDR) refers to the ratio of the maximum optical power to the minimum detectable optical power that a detector can linearly respond to, usually expressed in decibels (dB) , and can be represented as:
(5)
In the formula, Pmax is the maximum optical power of the linear response; Pmin is the minimum optical power of the linear response; Jmax is the maximum photocurrent density of the linear response; and Jmin is the minimum photocurrent density of the linear response [37].
Detectability D* is a core indicator of a detector's ability to detect weak signals. It comprehensively considers the effects of noise, detection area, and bandwidth, and can be expressed as:
(6)
In the formula, A is the effective area of the detector (cm²) ; Δf is the measurement bandwidth (Hz) ; and in is the dark current read from the noise spectral density at 1 Hz [38].
1.2 Current Status of Quantum Dot Shortwave Infrared Imaging Technology
Over the past five years, research teams both domestically and internationally have conducted extensive innovative research and achieved a series of groundbreaking results, focusing on core areas such as quantum dot material optimization, device structure design, and performance improvement. For example, Chen S et al. designed a hole transport layer for hybrid-sized PbS quantum dots, combining the high carrier mobility of small-sized (2－3 nm) quantum dots with the high light absorption coefficient of large-sized (6－8 nm) quantum dots, and successfully constructed a gradient band structure, which effectively suppressed carrier recombination. This structure reduced the dark current density of the detector to less than 50% of that of traditional single-size quantum dot devices (less than 5 μA/cm² at room temperature and －1 V bias) , increased the EQE of the 1500 nm band to 65%, and achieved a D* of 2.4×1012 Jones, with performance reaching the international advanced level [38].
On the other hand, Liu P et al. successfully developed a300, 000-pixel (640×480) PbS colloidal quantum dot SWIR imaging chip based on solution-based heterojunction technology. The chip's dark current density is below 50 nA/cm² (－0.5 V bias) , the EQE of peak band exceeds 60%, and the imaging resolution reaches 5 μm, laying a key foundation for the large-scale popularization of SWIR imaging technology [39].
Chang J et al. passivated PbS quantum dot surface defects through mercaptopropionic acid ligand exchange process, effectively optimized surface states, and reduced the room temperature dark current density of the device to 20 μA /cm², achieving an order of magnitude performance improvement compared to the2022 level. On this basis, in 2024, the team further introduced an alumina ultrathin insulating layer prepared by atomic layer deposition as an electron blocking layer, and through passivating interface defects and suppressing carrier recombination, stabilized the dark current density below 15 μA /cm². The corresponding room temperature D* increased to 2×10 12 Jones at a wavelength of 1550 nm and a bias voltage of －0.2 V, which fully meets the application requirements of medium and low precision industrial detection and security monitoring [40].
Meanwhile, Vafaie M et al. optimized the ligand exchange strategy by using halide passivating agents, which not only passivated the surface defects of quantum dots and improved quantum efficiency, but also stabilized the device's D* at 8×10 11 Jones, providing a new technical path for sensitivity control in high response speed scenarios [41].
2 Prospects for the Application of Quantum Dot Shortwave Infrared Cameras in Industrial Inspection
Industrial inspection is a crucial link in ensuring product quality, improving production efficiency, and realizing intelligent manufacturing. Traditional machine vision mainly relies on visible light (400－700 nm) imaging, which is not only easily affected by ambient light, object color, and surface reflection, but also cannot detect "hidden" indicators such as internal defects, chemical composition, and humidity content. When SWIR light interacts with matter, it can induce molecular vibrational energy level transitions, thus exhibiting characteristic absorption lines in substances containing chemical bonds such as OH, CH, and NH, enabling "composition analysis". Simultaneously, SWIR photons can penetrate silicon, certain plastics, and smoke, making it possible to observe the internal structure of products.
2.1 Material Defect Detection
Internal defects in industrial materials (such as cracks, pores, inclusions, and delamination) are the core hidden dangers affecting the safety and service life of products. Quantum dot SWIR cameras, with their high penetration ability and imaging contrast of SWIR light inside materials, provide a new solution for the rapid, accurate, and non-contact detection of internal defects, and achieve a good balance between sensitivity and cost control [42].
In the inspection of metallic materials, SWIR light can effectively penetrate surface oxide layers, protective coatings, and even metal substrates 1－3 mm thick. Quantum dot SWIR cameras, by capturing the difference in infrared radiation between defective areas and the normal substrate, can visualize hidden defects such as internal cracks and micropores, significantly improving the reliability and efficiency of inspection. In the field of composite materials, carbon fiber reinforced composites are widely used in aerospace and high-end equipment manufacturing due to their high specific strength and lightweight properties; however, internal defects such as interlaminar delamination in composite materials are difficult to identify using conventional methods. Quantum dot SWIR imaging technology can effectively identify interfacial debonding and interlaminar defects within such structures, providing a powerful non-destructive testing tool for the quality assessment of composite materials.
In the future, quantum dot SWIR cameras can be further developed towards high-end material customization. For the detection needs of special materials such as high-temperature alloys and advanced composite materials, customized quantum dot cameras with spectral responses can be developed. At the same time, combined with machine learning algorithms, automatic classification of defect types, size quantification and risk rating can be achieved, promoting the upgrading of industrial inspection to full-process intelligence and unmanned operation.
2.2 Semiconductor Manufacturing Monitoring
Semiconductor manufacturing is rapidly evolving towards high density, ultra-miniaturization, and multi-chip integration. The entire process, from wafer fabrication to chip packaging and reliability testing, requires non-contact, high-resolution, wide-spectrum, and real-time response monitoring technologies. Quantum dot SWIR cameras, with their core advantages of tunable spectrum, silicon-based compatibility, low-cost integration, and high penetration, overcome the limitations of traditional monitoring technologies in terms of detection range, cost control, and online adaptability, and are expected to become a new key technology for quality control throughout the entire semiconductor manufacturing process.
2.2.1 Inspection of Internal Structure and Alignment Marks of Bonded Wafers
Wafer fabrication is the core of semiconductor manufacturing, and its defect detection and process control directly determine device yield. Quantum dot SWIR cameras utilize the high penetrability of SWIR light to silicon-based materials to clearly observe alignment marks, bump structures, and microcracks and chipped edges on bonded wafers that are invisible to traditional visible light. These cracks create distinct dark signal features by blocking SWIR light transmission, facilitating rapid localization.
In 2023, Tan Y M et al. developed a 640×512 mercury telluride (HgTe) quantum dot focal plane array (15 μm pixel pitch) . By utilizing the high penetration of the SWIR band to silicon-based materials, internal defects (lattice distortion, impurity particles, etc.) of silicon wafers can be observed, as shown in Figure1 (a) and Figure1 (b) . They also utilized the fact that different semiconductor materials (such as silicon, gallium nitride, and silicon carbide) have different absorption coefficients in the SWIR band, and that material defects (such as scratches and voids) can cause local absorption anomalies, so these defects can be identified by grayscale differences [43].
2.2.2 Chip Packaging and Bonding Quality Monitoring
In key processes such as bonding, molding, and lead cutting in chip packaging, quantum dot SWIR cameras can achieve non-contact online monitoring. During wafer-level packaging, the flow state of the underfill adhesive and bubble defects directly affect the reliability of the device. In 2024, Liu Y et al. used electromagnetic interference passivation of PbS quantum dot thin film transistor imagers, covering the 0.35－1.8 μm band, with a linear dynamic range of 100 dB and a detection rate of 99.7% for 0.5 μm bubbles. It has been used for real-time monitoring of the underfill process [44]. The device performance is shown in Figure2 (c) .
Meanwhile, bonding defects and lead misalignment in the packaging process can directly affect the reliability of the device. If a quantum dot SWIR camera is used, real-time quality control of the packaging process can be achieved. In the evaluation of hybrid bonding quality, Li L et al. proposed a continuous domain bound state metasurface enhancement scheme, which excites high-Q guided wave modes through silicon-based subwavelength structures, thereby enhancing the fluorescence emission of PbS quantum dots at 1408 nm, with a Q value of 251, which significantly improves the sensitivity of identifying voids at the bonding interface [45].
2.2.3 Reliability assessment of devices
Quantum dot SWIR cameras offer a multi-dimensional solution for reliability testing of semiconductor devices, covering key testing scenarios such as thermal stability, hermeticity, and long-term aging. In thermal stability testing, through thermal cycling experiments from －40℃ to 85℃, the camera can observe the evolution of defects in the package structure in real time (imaging) , assess the thermal fatigue performance of materials, and simultaneously monitor the temperature distribution in different regions of the device, accurately identifying heat concentration issues. In hermeticity testing, based on the sensitivity of SWIR light to moisture, leak locations can be pinpointed by analyzing changes in local spectral response, resulting in a detection sensitivity improvement of an order of magnitude compared to traditional methods. For long-term aging monitoring, the camera can periodically detect the growth of internal defects in devices during high-temperature and high-humidity accelerated aging experiments, providing accurate data support for device lifetime prediction.
In the future, the requirements for inspection technology in semiconductor manufacturing will be further enhanced. It is necessary to develop high frame rate (greater than 1000 fps) quantum dot SWIR cameras to adapt to the inspection needs of high-speed semiconductor production lines. At the same time, combined with near-field optical technology, defect detection at nanometer resolution can be achieved to meet the manufacturing quality control requirements of advanced processes below 3 nm.
2.3 High-Temperature Process Monitoring
In the petrochemical industry, the internal temperatures of equipment such as refining furnaces and gas turbines can reach hundreds or even thousands of degrees Celsius. Traditional contact temperature measurement methods are susceptible to corrosion in high-temperature environments and have slow response times; conventional infrared temperature measurement is greatly affected by environmental smoke and dust. Quantum dot SWIR cameras not only have strong penetrating power in high-temperature environments but also exhibit high sensitivity to radiation signals from high-temperature objects, enabling non-contact, precise temperature measurement and real-time monitoring of high-temperature processes.
For example, in 2024, Deng H Y et al. [46] developed an ultrathin PbS quantum dot detector, which achieved a response time of 4 ns through the design of a100 nm ultrathin absorption layer. The detector has an external quantum efficiency of 42% at 1330 nm and can monitor the high-temperature deformation of gas turbine blades. The device and its performance are shown in Figure2 (d) and Figure2 (e) .
Furthermore, Raytron's thermal imaging cameras offer a wide measurement range from －20℃ to 2000℃, with accuracy maintained within ±2% or ±2℃. By converting invisible heat energy into clear thermal images, handheld thermal imagers can comprehensively scan large areas in seconds, significantly improving inspection efficiency and reducing operational risks. This non-contact temperature measurement method is suitable for high-risk environments such as high-voltage power systems, operating oil refineries, and areas containing hazardous chemicals.
In the field of aero-engine monitoring, the bearing system of its high-speed rotating machinery will generate significant temperature rise during operation. Therefore, temperature monitoring of its internal rotating parts is the key to assessing equipment status and preventing failures. Zhang Pan et al. [47] developed a temperature sensor based on cadmium telluride (CdTe) quantum dots. By controlling the experimental conditions for preparing CdTe quantum dots (preparation time and ligands) , they used structural characterization to explore the influence mechanism of the microstructure and average particle size of quantum dots on their fluorescence properties. Finally, the prepared CdTe/polyvinyl alcohol high-stability sensor achieved significant improvements in quantum dot fluorescence intensity, maximum tolerance temperature, sensitivity and stability. The advantage of this high-temperature resistant quantum dot sensor is that it can achieve non-contact temperature measurement and has a fast response speed. It can capture the transient temperature changes of rotating parts, detect abnormal temperature rises in time, and avoid equipment damage.
Fig.2: (a) － (b) Perspective views of silicon wafers taken by visible light silicon imager and quantum dot thin film transistor imager respectively [43]; (c) Comparison of measured photoluminescence spectra of patterned metasurface (black curve) and unpatterned region on the same chip (red curve) [44]; (d) Schematic diagram of cross-section of proposed quantum dot photodetector stack structure and actual scanning electron microscope image; (e) Current-voltage characteristic curves under dark and light conditions and external quantum efficiency spectrum of quantum dot photodetector stack structure [47].
2.4 Liquid Sorting
The typical application of SWIR camera in the field of "material perception" can be intuitively demonstrated through the liquid sorting scenario: the four transparent liquids in the experiment are trichloroethylene, deionized water, polycarboxylate superplasticizer and bis (p-chlorophenyl) trichloroethane. Under the visible light imaging perspective, they cannot be distinguished because they are all transparent. However, when the quantum dot SWIR camera is switched to imaging (see Figure3 (b) ) , due to the differences in molecular structure of different liquids, the absorption capacity of liquids to SWIR light is different. This absorption difference is directly converted into significantly different gray values in the image, which ultimately makes the four liquids that were originally difficult to distinguish clear and provides precise technical support for efficient sorting [48].
Fig.3: Liquid color sorting imaging based on a CQD SWIR camera [48].
3 Prospects for the Application of Quantum Dot Short-Wave Infrared Cameras in the Food/Agriculture Field
The food and agriculture sectors are continuously raising their requirements for product quality and safety. Traditional testing methods (such as sensory evaluation and chemical analysis) have limitations such as high subjectivity, long processing times, and high destructiveness, making it difficult to meet the needs of large-scale production and precise control. Quantum dot SWIR cameras utilize the characteristic spectral response of substances in the SWIR band to achieve rapid, non-contact, and non-destructive testing, providing a new technological approach for food quality grading, component analysis, safety monitoring, and precise control of agricultural production.
3.1 Agricultural Product Quality Testing
The quality parameters of agricultural products (fruits, grains, meats, etc.) , such as moisture content, sugar content, ripeness, and degree of damage, directly determine their commercial value. Agricultural products of different qualities exhibit unique spectral characteristics in the SWIR band, providing a foundation for rapid grading using quantum dot SWIR cameras. This technology, combined with chemometric models, can simultaneously detect multiple quality parameters, achieving multi-dimensional and highly efficient quality assessment, and has already been practically applied in scenarios such as fruit sorting and vegetable freshness detection.
The research team of Optics Valley Laboratory has applied quantum dot SWIR imaging chips to automated fruit sorting. By penetrating the epidermis to detect internal defects, it has solved the problems of water core disease and browning that are difficult to identify by traditional visual inspection. In 2024, Heyan M et al. developed a single-pixel SWIR hyperspectral imaging system based on PbS quantum dot self-assembled filter. The system uses digital micromirror array for spectral encoding and combines compressed sensing algorithm to achieve low-cost and miniaturized spectral imaging. In strawberry detection, the system can image fresh strawberries and distinguish between pulp (high moisture, reflectance spectrum similar to water) , sepals (chlorophyll characteristic peaks) and seeds (low moisture, high reflectance) . The extracted reflectance spectrum deviates from that of commercial spectrometers by less than 2%, proving its non-destructive detection capability. In addition, it can also quantify the sugar-acid ratio, chlorophyll content and other maturity indicators through spectral feature differences. Compared with traditional detection methods, this technology can reduce costs by more than 90% while maintaining a detection accuracy of more than 99%, which greatly improves the efficiency and economy of agricultural product sorting [49].
Fig.4: Hyperspectral images of reflective objects: (a) Color photograph of fresh strawberry; (b) Hyperspectral image of fresh strawberry; (c) － (d) Reconstructed reflectance spectra of strawberry pulp and strawberry calyx; (e) － (f) Color photograph of a mixture of real grass and plastic grass; (h) Hyperspectral image of plastic grass; (g) Reconstructed reflectance spectrum of real grass [49].
3.2 Food composition analysis and safety screening
Quantum dot SWIR imaging technology has unique advantages in food component analysis and authenticity identification. Different food components (such as water, protein, fat and carbohydrates) have characteristic absorption spectra in the SWIR band, making it possible to perform quantitative component analysis through SWIR spectral imaging technology. Compared with traditional chemical component analysis methods, SWIR imaging does not require sample pretreatment and can simultaneously obtain spatial distribution information to realize the visualization of component distribution. For example, in meat product analysis, the moisture, protein and fat content can be measured simultaneously, and the distribution of marbled fat can be displayed intuitively; in grain quality detection, the protein, starch and moisture content can be measured simultaneously, thereby comprehensively evaluating quality indicators [50].
In terms of food safety testing, food may be contaminated in various ways during production, processing, storage and transportation, including physical contamination (foreign objects) , chemical contamination (pesticide and veterinary drug residues, heavy metals) and biological contamination (microorganisms, molds) . The penetrating power of SWIR light enables it to detect foreign objects inside food, such as plastics, glass, stones and the like. These foreign objects are often covered by the food itself under visible light, but they will show obvious contrast differences in specific SWIR bands [50].
For example, in the inspection of packaged food, quantum dot SWIR cameras can penetrate packaging materials and directly detect foreign matter inclusions inside the product, greatly improving the comprehensiveness and accuracy of the inspection. In 2023, Sultana S T et al. developed an InGaAs-based SWIR camera. It can detect glass fragments (size≥0.5 mm) in grains, with an overall detection accuracy of 99% and a false positive rate of less than 0.8%. Regardless of 0.5 mm. The camera can accurately identify even tiny impurities of 0.5 mm or transparent plastic, and it can also adapt to different kinds of vegetables [51].
In the detection of pesticide residues and additives, quantum dot hyperspectral imaging technology can capture the characteristic absorption peaks of specific pollutants. Meng H Y et al. developed a single-pixel detection system based on PbS quantum dot self-assembled filters. Its working band covers 1050－1630 nm, and the spectral resolution reaches 8.59 nm. Its noise resistance is better than that of traditional array detectors. Moreover, the system supports non-destructive detection, and the band range can match the characteristic absorption peaks of organophosphorus pesticides (such as methyl parathion) . It can capture the weak spectral changes caused by trace pesticide residues by utilizing its high sensitivity characteristics, which provides a technical basis for subsequent expansion to the accurate detection of pesticide residues in food (such as detection limits as low as 0.1~1 ppm) [52].
Fig.5: (a) Detection of foreign matter in fresh sliced carrots [51]; (b) Transmission spectrum of the filter and absorption spectrum of lead sulfide quantum dots in solution [52-53]; (c) － (d) Comparison of transmission spectra of traditional stepped filter and CQD filter [54].
3.3 Precision Management of Agricultural Production
Quantum dot SWIR imaging technology also shows great potential in monitoring crop physiological status. When crops are subjected to environmental stress (such as drought, pests and diseases, nutrient deficiency, etc.) during growth, the optical properties of their leaves and canopy will show regular changes in the SWIR band. These changes are invisible to the naked eye, but can be accurately captured by a SWIR camera. Studies have shown that SWIR-based spectral monitoring models can quickly and non-destructively detect changes in the reflectance spectrum of crop canopy and leaves, analyze the hyperspectral response patterns and spatiotemporal variation patterns of crops under different conditions, and provide a scientific basis for real-time assessment of crop growth status [53]. For example, by extracting the characteristic spectral bands and sensitive spectral parameters of the main growth indicators of crops, a multi-scale spectral monitoring model of crop growth indicators such as leaves, canopy, and region can be constructed, thereby achieving accurate diagnosis of crop growth status.
The quantum dot SWIR camera's wide-spectrum detection capability (400－1700 nm) enables it to capture plant physiological changes that are not detectable by visible light cameras. In the early stages of crop disease and pest infestation, subtle changes occur in the internal structure of leaves and water distribution. These changes are reflected in specific reflectance features in SWIR images, allowing farmers to take intervention measures before symptoms are visible to the naked eye, significantly reducing crop losses [50].
For example, in 2025, Sandhya M et al. used quantum dots to track and study the interaction between plants and pathogens (such as fungi, bacteria, and viruses) to achieve early diagnosis of diseases. It provides a theoretical basis and technical background for the construction of high-sensitivity sensors using quantum dot nanomaterials [54], and promotes its application in SWIR detection. This method can achieve large-area, online rapid monitoring without damaging crops, which greatly improves efficiency. By judging through image algorithms, the infected area can be accurately located, reducing the influence of human subjective experience and making the results more accurate and reliable.
In the future, it may be possible to develop lightweight, low-power quantum dot SWIR cameras that are compatible with mobile platforms such as drones and agricultural robots; and to build an agricultural big data platform that combines remote sensing data with ground detection data to achieve dynamic monitoring and intelligent decision-making throughout the entire crop growth cycle.
4 Prospects for the Application of Quantum Dot Short-Wave Infrared Cameras in the Biomedical Field
The SWIR band is a low-loss optical window for biological tissues. Biological tissues significantly reduce the scattering and absorption of photons in this band, allowing photons to penetrate deep tissues of several millimeters to several centimeters, thereby achieving high-contrast in vivo imaging [55].
The continued maturation of quantum dot SWIR imaging technology has not only broken through the performance and cost bottlenecks of traditional SWIR imaging equipment, but has also facilitated the practical application of high-resolution, low-cost SWIR cameras. This technological breakthrough perfectly aligns with the core biomedical need for deep and precise imaging, and is driving SWIR imaging technology to widely penetrate from specialized laboratory settings into biomedical fields such as cancer research, tissue function assessment, and clinical diagnosis.
4.1 Disease Diagnosis and In Vivo Imaging
4.1.1 Superficial vascular imaging and blood flow monitoring
In the SWIR band, biological tissues have unique optical response characteristics: the O-H bonds of water in blood have a strong absorption peak near 1450 nm, while the tissue itself exhibits relatively transparent optical behavior near 1300 nm, forming a natural absorption contrast [56]. With the help of this characteristic, SWIR imaging technology can directly and clearly present the distribution and morphology of subcutaneous vascular networks without relying on contrast agents, providing core technical support for non-invasive vascular observation.
In addition, STMicroelectronics demonstrated a PbS quantum dot SWIR image sensor based on a300 mm wafer CMOS-compatible process at the2021 International Electron Devices Conference [56]. This technology has successfully verified the feasibility of applications such as vascular imaging, and thanks to the compatibility of large-size wafers with CMOS processes, its manufacturing cost is expected to drop to a level comparable to that of standard CMOS sensors, completely breaking the cost barrier of traditional SWIR imaging equipment.
This technological breakthrough provides a new path for medical device innovation: it can not only develop low-cost, handheld vein locators to assist in clinical puncture, infusion and other operations; but also be used in scenarios such as blood flow monitoring after flap transplantation, burn depth assessment and peripheral vascular disease diagnosis, providing a real-time, non-invasive blood perfusion detection solution for precision medicine and promoting the large-scale application of SWIR imaging technology in clinical diagnosis and treatment.
4.1.2 Non-invasive temperature measurement of tumor and blood flow
Quantum dot SWIR detectors have the potential to be used for non-invasive measurement of the temperature of tumors and blood flow [57]. Due to abnormal metabolism and angiogenesis in tumor tissues, their surface temperature is usually different from that of the surrounding normal tissues. Highly sensitive quantum dot infrared cameras can capture such weak infrared signals caused by temperature radiation, providing a new label-free method for early screening and diagnosis of tumors. In 2012, Zhang Y et al. [58] detailed the application of silver sulfide quantum dots in the near-infrared II window. The research team collaborated with Professor Hongjie Dai of Stanford University to achieve high-resolution imaging of blood vessels in the mouse brain using Ag2S QDs and demonstrated its application potential in brain tumor imaging.
4.2 Intraoperative navigation and tumor margin delineation
Biological tissues are mainly composed of water, lipids (fat) , and proteins, which exhibit distinctly different spectral absorption characteristics in the SWIR band (for example, lipids have absorption peaks near 1210 nm and 1720 nm, while water has strong absorption at 1450 nm) . In surgical procedures, the "chemical fingerprinting" capabilities of low-cost quantum dot SWIR detectors will greatly advance the development of label-free intraoperative navigation.
Early diagnosis and precise resection of tumors are key to improving patient survival rates. Quantum dot SWIR cameras can specifically identify tumor cells through targeted imaging and deep penetration characteristics, enabling early detection of small tumor lesions. Santos HDA et al. [59] increased the quantum yield of silver sulfide quantum dots by 80 times after femtosecond laser treatment. Under low excitation intensity (less than 10 mW·cm-2) and low dose (less than 0.5 mg·kg-1) conditions, high-contrast imaging of 12 mm deep tumors in mice was achieved by taking advantage of the low scattering and low autofluorescence of the1200 nm near-infrared II window. The results showed that the contrast between tumor and normal tissue was increased by 50 times, and tumor neovascularization and micrometastases could be clearly distinguished, successfully achieving high-contrast imaging of deep tumors in mice.
In terms of intraoperative navigation, Hwang J et al. [60] developed a quantum dot magnetic guidewire system that embeds mercury cadmium selenide quantum dots into a flexible guidewire. The position of the guidewire is monitored in real time by a SWIR camera, and the magnetic manipulation technology is combined to realize X-ray-free navigation for peripheral vascular interventional therapy. The imaging depth of the system in simulated tissue is 10 mm, and the guidewire can be precisely turned at the bifurcation of the blood vessel, avoiding radiation damage to doctors and patients from X-rays, and providing a safe and efficient navigation scheme for tumor interventional therapy. In addition, the development of multicolor SWIR imaging technology has made it possible to visualize tumor blood vessels and lymphatic systems at the same time, providing a new means for tumor metastasis monitoring.
4.3 Visual monitoring of cell therapy
The efficacy assessment of cell therapy has long been limited by the inability to track cells in vivo in real time. The advantage of quantum dot SWIR imaging is that it takes into account both penetration depth and cell activity. This non-invasive tracking mode breaks through the limitations of traditional tissue biopsy, enabling cell therapy to move from "black box operation" to "transparent monitoring" era. The live cell tracking system developed by Chen M et al . [61] uses PbS quantum dots as fluorescent probes to label M2 macrophages, and with the help of the deep penetration of the SWIR camera, high stability (signal attenuation of only 8.7% after 28 days) , and low cytotoxicity (cell viability maintained at 98.3%) , this system enables full-process visual tracking of M2 macrophage therapy in muscle injury repair, clearly revealing the dynamic aggregation process of treated cells at the injury site. Combined with AI analysis algorithms, the system can predict the repair effect 7 days in advance based on 72-hour post-injury imaging data, achieving an accuracy rate of 89.4%. They have constructed an integrated technical solution of "quantum dot labeling－SWIR imaging tracking－AI precise analysis", providing key technical support for the precise and personalized development of cell therapy.
5 Prospects for the Application of Quantum Dot Shortwave Infrared Cameras in Consumer Electronics
5.1 Mobile Devices and Biometrics
The transparency of organic light-emitting diode (OLED) screens in the SWIR band allows quantum dot SWIR sensors to be integrated under the screen, enabling true under-display cameras and multimodal sensing. SWIR light can be absorbed by superficial water and lipids in the skin, clearly imaging the distribution of subcutaneous veins, creating a vein recognition system that is more difficult to forge than fingerprints or two-dimensional facial features.
For example, based on indium arsenide quantum dots, the1450 nm band sensing can realize the detection of deep features such as blood vessel patterns and skin moisture, which complies with the Restriction of Hazardous Substances (RoHS) [62] and is perfectly suited to the biometric needs of mobile phones and wearable devices.
In terms of material identification, quantum dot SWIR detectors are integrated into devices such as smartphones to meet consumer needs such as food freshness detection and skin care product ingredient identification. Silver telluride quantum dot sensors have successfully demonstrated the function of detecting the contents of plastic bottles. Bismuth doping modification can effectively reduce its defect density, improve the utilization rate of photogenerated carriers, and ensure the stability of detection [63].
In augmented reality (AR) and virtual reality (VR) head-mounted displays, SWIR cameras enable high-precision eye tracking. Compared to traditional red or near-infrared solutions, the use of SWIR light sources, which are invisible to the human eye, does not cause visual interference or eye discomfort [64], and the use of lead-free quantum dot materials further enhances the safety of the device.
In the field of consumer machine vision, quantum dot SWIR cameras integrated into smartphones or AR glasses can utilize the spectral properties of matter to achieve "material sensing" functions such as fruit sugar/moisture detection, skin condition analysis, and plastic/textile sorting [64]. Based on the multispectral design of the meta-surface, the device can also acquire multiple dimensions in a single shot, expanding the application scenarios of consumer machine vision.
In addition, quantum dot SWIR face recognition is not affected by masks, sunglasses and ambient light. Combined with three-dimensional sensing technology, it is expected to become the mainstream solution for identity verification of next-generation mobile devices [66]. Optics Valley Laboratory has cooperated with companies such as Huawei on PbS quantum dot imaging chips to promote the integration and testing of mobile phone modules [67].
5.2 Automotive Electronics and Autonomous Driving
The demand for all-weather, highly reliable environmental perception capabilities in autonomous driving assistance systems is becoming increasingly urgent. SWIR cameras can effectively compensate for the performance shortcomings of visible light cameras in adverse weather conditions. Specifically, 1550 nm is a safe wavelength for the human eye, allowing for the use of higher power laser illumination schemes. Combined with the high sensitivity characteristics of quantum dot detectors, it can achieve detection at a greater distance [68], while effectively penetrating adverse weather conditions such as fog, smoke, rain, and dust [69], significantly improving the vehicle's accuracy and distance in identifying key targets such as pedestrians, animals, and road ice and water accumulation.
Furthermore, quantum dot SWIR sensors can be integrated into in-vehicle driver monitoring systems. Their unique spectral response characteristics allow them to penetrate sunglasses, accurately monitoring the driver's eye status (such as blink frequency and gaze direction) and effectively resisting strong light and glare interference, providing dual protection for driving safety. Simultaneously, these sensors possess inherent CMOS compatibility, enabling seamless integration with automotive chips; coupled with the inherent stability of quantum dot materials, they can meet the stringent requirements of automotive electronics regarding cost, reliability, and integration.
HgTe quantum dot focal plane array developed by Huazhong University of Science and Technology has passed the reliability test in extreme environments of －40℃－105℃, and the performance degradation is controlled within 3% [70], which fully meets the environmental adaptability requirements of vehicle scenarios. This technology can be widely integrated into vehicle-mounted forward-looking cameras and surround-view systems, forming multimodal perception fusion with lidar and millimeter-wave radar, further improving the comprehensiveness, accuracy and redundancy of environmental perception in autonomous driving systems, and providing core technical support for the implementation of high-level autonomous driving.
5.3 Security and Consumer-Grade Night Vision
Traditional night vision technologies are mainly divided into two categories: low-light amplification and thermal imaging. However, both of them have inherent shortcomings: low-light amplification technology is highly dependent on ambient light and cannot work in "zero light" scenarios; thermal imaging technology can achieve detection without light, but it can only capture the outline image formed by the temperature difference of objects and it is difficult to restore details such as facial features and object textures [65]. SWIR night vision technology perfectly makes up for the above defects through the active illumination scheme of the1550 nm band. This band is a safe band that is invisible to the human eye. It has strong concealment when actively illuminated and can clearly present the real texture and facial features of objects in "zero light" environment without relying on ambient light [65]. The breakthrough of quantum dot SWIR detectors in terms of cost reduction has completely broken the price barrier of traditional SWIR imaging equipment, making it possible for consumer products such as home security cameras and portable night vision devices to be deployed on a large scale.
In addition, quantum dot detectors have a wide spectral response (covering300 nm to 2.1 μm, encompassing visible light, near infrared and SWIR bands) [69], enabling integrated day and night imaging: during the day, high-resolution color images are obtained by relying on the visible light-near infrared band, and at night, the detector switches to the SWIR band for active illumination detection without the need for additional equipment or modes, which significantly improves the practicality and convenience of consumer-grade security products.
5.4 Other extended consumer applications
With its unique optical characteristics and functional advantages, SWIR technology has demonstrated wide application value in many areas of people's lives, including health monitoring, smart home appliances, and outdoor equipment, in addition to its core application scenarios.
In the field of health monitoring, SWIR sensing technology can accurately realize functions such as skin moisture content detection and vascular health status assessment by virtue of its non-invasive detection advantage [62]. Based on its miniaturization and low power consumption characteristics, it can be seamlessly integrated with wearable devices such as smart bracelets and health watches to provide users with real-time and convenient health data support.
In the field of smart home appliances, SWIR sensors can automatically and accurately identify clothing materials by utilizing the differences in the characteristic absorption of the SWIR band by different clothing fibers. Washing machines integrating this sensor can intelligently optimize washing parameters (such as water temperature, spin speed, and detergent dosage) based on the identification results, improving cleaning performance while reducing damage to clothes, thus achieving refined care.
In the field of outdoor equipment, action cameras equipped with quantum dot SWIR modules can capture clear images in complex weather conditions such as fog, rain, and low light, thanks to the high sensitivity and harsh environment resistance of quantum dot detectors. This accurately meets the high-definition shooting needs of outdoor adventure, extreme sports and other scenarios, providing outdoor enthusiasts with a reliable image recording solution.
6 Summary and Outlook
Quantum dot SWIR detectors, with their core advantages such as tunable spectrum, low cost, solution-processability, and compatibility with CMOS processes, have opened up a new path for the large-scale popularization of SWIR imaging technology. This review shows that this technology has made significant progress in materials, device performance, and application expansion, with performance indicators gradually approaching and even surpassing traditional InGaAs detectors in some application scenarios. However, to achieve its full industrialization and meet the needs of high-end applications, a series of technical bottlenecks still need to be overcome.
6.1 Lower noise and higher detection sensitivity
Noise is a key factor limiting the detection of weak signals, and dark current (thermally excited carriers, surface defect leakage current, etc.) is the main source of noise. Current PbS quantum dot detectors have dark current densities as low as 50 nA/cm², but further reductions are needed for high-precision spectral analysis and deep biological tissue imaging. The core challenge lies in addressing surface defects in quantum dots (such as deep-level traps formed by Pb²⁺ dangling bonds and S²⁻ vacancies on the PbS quantum dot surface) , reducing non-radiative recombination and leakage of carriers, thereby improving detectivity and meeting the detection requirements of even weaker signals (such as low-concentration pesticide residues and tiny tumor lesions) .
6.2 Higher carrier mobility and faster response speed
The low carrier mobility of quantum dot films is mainly due to the ligands between quantum dots hindering carrier tunneling, and surface defects forming carrier traps, resulting in low carrier transport efficiency and consequently affecting the detector's response time. While some current devices have achieved response times of 4 ns, further improvements are needed for applications such as high-speed semiconductor production lines (frame rates greater than 1000 fps) and dynamic high-temperature process monitoring. Future development will focus on improving carrier mobility and shortening response time through ligand engineering (optimizing quantum dot surface ligands to reduce obstruction) and heterostructure design (such as gradient band structures to suppress recombination) .
6.3 Superior long-term stability and adaptability to extreme environments
In practical applications, detectors need to cope with complex environments: for automotive applications, they must withstand temperature fluctuations of －40 to 105℃; for industrial high-temperature monitoring applications, they must withstand radiation of hundreds or even thousands of degrees; and for biomedical applications, they must be biocompatible and resistant to liquid corrosion. While HgTe quantum dot focal plane arrays have passed environmental testing at －40℃ to 105℃ (performance degradation less than 3%) , their stability in more extreme environments (such as high temperatures in aerospace and strong radiation) still needs to be verified. Furthermore, the antioxidant and anti-aging properties of quantum dot materials need further optimization to extend the lifespan of the devices.
6.4 Higher resolution and consistency with mass production
The advancement of semiconductor manufacturing towards advanced processes below 3 nm necessitates defect detection at nanometer-level resolution. While current quantum dot detectors can achieve5 μm imaging resolution, overcoming the nanometer-level resolution bottleneck requires the integration of near-field optics. Furthermore, although solution processing is beneficial for large-scale production, the uniformity of large-area quantum dot films and the performance consistency of batch devices (such as batch variations in dark current and external quantum efficiency) still need improvement to meet the capacity and yield requirements of large-scale applications such as consumer electronics and industrial inspection.
6.5 Lead-free and environmentally friendly
Current mainstream quantum dot materials contain toxic elements such as lead and mercury, which do not comply with environmental standards such as RoHS, limiting their application in consumer electronics, biomedicine, and other scenarios involving contact with the human body. Although there has been exploration of lead-free quantum dots such as indium antimonide and silver telluride, the spectral response range and detection performance (such as external quantum efficiency and dark current) of these materials are still inferior to those of PbS quantum dots. Therefore, further optimization of material systems and preparation processes is needed to achieve the dual goals of "environmentally friendly & high performance".
Looking ahead, through interdisciplinary collaboration involving materials innovation, advancements in device physics, and refinements in process engineering, the performance of quantum dot SWIR detectors is expected to achieve further breakthroughs. With performance improvements, their integration with cutting-edge technologies such as artificial intelligence, flexible electronics, and on-chip spectroscopy will become more profound and efficient: AI algorithms can optimize the accuracy of imaging data analysis; flexible electronics can expand applications in wearable and irregularly shaped environments; and on-chip spectroscopy can enhance the ability to identify material composition. This will continuously expand the application boundaries of SWIR imaging, ultimately propelling the technology to achieve a crucial leap from laboratory innovation to industrial transformation.