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2 pages, 146 KiB

Open AccessEditorial

Special Issue “Application of Advanced Quantum Dots Films in Optoelectronics”

by Xin Tang

Coatings 2023, 13(3), 589; https://doi.org/10.3390/coatings13030589 - 9 Mar 2023

Viewed by 877

Abstract

Colloidal quantum dots (CQDs) have been extensively investigated in recent decades [...] Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

Research

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11 pages, 3476 KiB

Open AccessArticle

Simulation and Design of HgSe Colloidal Quantum-Dot Microspectrometers

by Chong Wen, Xue Zhao, Ge Mu, Menglu Chen and Xin Tang

Coatings 2022, 12(7), 888; https://doi.org/10.3390/coatings12070888 - 22 Jun 2022

Cited by 3 | Viewed by 1731

Abstract

In recent years, colloidal quantum dots (CQD) have been intensively studied in various fields due to their excellent optical properties, such as size-tunable absorption features and wide spectral tunability. Therefore, CQDs are promising infrared materials to become alternatives for epitaxial semiconductors, such as [...] Read more.

In recent years, colloidal quantum dots (CQD) have been intensively studied in various fields due to their excellent optical properties, such as size-tunable absorption features and wide spectral tunability. Therefore, CQDs are promising infrared materials to become alternatives for epitaxial semiconductors, such as HgCdTe, InSb, and type II superlattices. Here, we report a simulation study of a microspectrometer fabricated by integrating an intraband HgSe CQD detector with a distributed Bragg reflector (DBR). Intraband HgSe CQDs possess unique narrowband absorption and optical response, which makes them an ideal material platform to achieve high-resolution detection for infrared signatures, such as molecular vibration. A microspectrometer with a center wavelength of 4 µm is studied. The simulation results show that the optical absorption rate of the HgSe CQD detector can be increased by 300%, and the full-width-at-half-maximum (FWHM) is narrowed to 30%, realizing precise regulation of the absorption wavelength. The influence of the incident angle of light waves on the microspectrometer is also simulated, and the results show that the absorption rate of the HgSe quantum dot detector is increased 2–3 times within the incident angle of 0–23 degrees, reaching a spectral absorption rate of more than 80%. Therefore, we believe that HgSe CQDs are a promising material for realizing practical HgSe microspectrometers. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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8 pages, 1399 KiB

Open AccessArticle

Simulation of Resonant Cavity-Coupled Colloidal Quantum-Dot Detectors with Polarization Sensitivity

by Pengfei Zhao, Ge Mu, Menglu Chen and Xin Tang

Coatings 2022, 12(4), 499; https://doi.org/10.3390/coatings12040499 - 7 Apr 2022

Cited by 4 | Viewed by 1600

Abstract

Infrared detectors with polarization sensitivity could extend the information dimension of the detected signals and improve target recognition ability. However, traditional infrared polarization detectors with epitaxial semiconductors usually suffer from low extinction ratio, complexity in structure and high cost. Here, we report a [...] Read more.

Infrared detectors with polarization sensitivity could extend the information dimension of the detected signals and improve target recognition ability. However, traditional infrared polarization detectors with epitaxial semiconductors usually suffer from low extinction ratio, complexity in structure and high cost. Here, we report a simulation study of colloidal quantum dot (CQD) infrared detectors with monolithically integrated metal wire-grid polarizer and optical cavity. The solution processibility of CQDs enables the direct integration of metallic wire-grid polarizers with CQD films. The polarization selectivity of HgTe CQDs with resonant cavity-enhanced wire-grid polarizers are studied in both short-wave and mid-wave infrared region. The extinction ratio in short-wave and mid-wave region can reach up to 40 and 60 dB, respectively. Besides high extinction ratio, the optical cavity enhanced wire-grid polarizer could also significantly improve light absorption at resonant wavelength by a factor of 1.5, which leads to higher quantum efficiency and better spectral selectivity. We believe that coupling CQD infrared detector with wire-grid polarizer and optical cavity can become a promising way to realize high-performance infrared optoelectronic devices. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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7 pages, 2156 KiB

Open AccessArticle

Mid-IR Intraband Photodetectors with Colloidal Quantum Dots

by Xue Zhao, Ge Mu, Xin Tang and Menglu Chen

Coatings 2022, 12(4), 467; https://doi.org/10.3390/coatings12040467 - 30 Mar 2022

Cited by 11 | Viewed by 2387

Abstract

In this paper, we investigate an intraband mid-infrared photodetector based on HgSe colloidal quantum dots (CQDs). We study the size, absorption spectra, and carrier mobility of HgSe CQDs films. By regulating the time and temperature of the reaction during synthesis, we have achieved [...] Read more.

In this paper, we investigate an intraband mid-infrared photodetector based on HgSe colloidal quantum dots (CQDs). We study the size, absorption spectra, and carrier mobility of HgSe CQDs films. By regulating the time and temperature of the reaction during synthesis, we have achieved the regulation of CQDs size, and the number of electrons doped in conduction band. It is experimentally verified by the field effect transistor measurement that dark current is effectively reduced by a factor of 10 when the 1Se state is doped with two electrons compared with other doping densities. The HgSe CQDs film mobility is also measured as a function of temperature the HgSe CQDs thin film detector, which could be well fitted by Marcus Theory with a maximum of 0.046 ± 0.002 cm²/Vs at room temperature. Finally, we experimentally discuss the device performance such as photocurrent and responsivity. The responsivity reaches a maximum of 0.135 ± 0.012 A/W at liquid nitrogen temperature with a narrow band photocurrent spectrum. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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8 pages, 3518 KiB

Open AccessCommunication

Simulation of Monolithically Integrated Meta-Lens with Colloidal Quantum Dot Infrared Detectors for Enhanced Absorption

by Yan Ning, Shuo Zhang, Yao Hu, Qun Hao and Xin Tang

Coatings 2020, 10(12), 1218; https://doi.org/10.3390/coatings10121218 - 14 Dec 2020

Cited by 8 | Viewed by 2238

Abstract

Colloidal quantum dots (CQDs) have been intensively investigated over the past decades in various fields for both light detection and emission applications due to their advantages like low cost, large-scale production, and tunable spectral absorption. However, current infrared CQD detectors still suffer from [...] Read more.

Colloidal quantum dots (CQDs) have been intensively investigated over the past decades in various fields for both light detection and emission applications due to their advantages like low cost, large-scale production, and tunable spectral absorption. However, current infrared CQD detectors still suffer from one common problem, which is the low absorption rate limited by CQD film thickness. Here, we report a simulation study of CQD infrared detectors with monolithically integrated meta-lenses as light concentrators. The design of the meta-lens for 4 μm infrared was investigated and simulation results show that light intensity in the focused region is ~20 times higher. Full device stacks were also simulated, and results show that, with a meta-lens, high absorption of 80% can be achieved even when the electric area of the CQD detectors was decreased by a factor of 64. With higher absorption and a smaller detector area, the employment of meta-lenses as optical concentrators could possibly improve the detectivity by a factor of 32. Therefore, we believe that integration of CQD infrared detectors with meta-lenses could serve as a promising route towards high performance infrared optoelectronics. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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Review

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17 pages, 4889 KiB

Open AccessReview

X-ray Detectors Based on Halide Perovskite Materials

by Yimei Tan, Ge Mu, Menglu Chen and Xin Tang

Coatings 2023, 13(1), 211; https://doi.org/10.3390/coatings13010211 - 16 Jan 2023

Cited by 5 | Viewed by 3160

Abstract

Halide perovskite has remarkable optoelectronic properties, such as high atomic number, large carrier mobility-lifetime product, high X-ray attenuation coefficient, and simple and low-cost synthesis process, and has gradually developed into the next-generation X-ray detection materials. Halide perovskite-based X-ray detectors can improve the sensitivity [...] Read more.

Halide perovskite has remarkable optoelectronic properties, such as high atomic number, large carrier mobility-lifetime product, high X-ray attenuation coefficient, and simple and low-cost synthesis process, and has gradually developed into the next-generation X-ray detection materials. Halide perovskite-based X-ray detectors can improve the sensitivity and reduce the detectable X-ray dose, which is applied in imaging, nondestructive industrial inspection, security screening, and scientific research. In this article, we introduce the fabrication methods of halide perovskite film and the classification and progress of halide perovskite-based X-ray detectors. Finally, the existing challenges are discussed, and the possible directions for future applications are explored. We hope this review can stimulate the further improvement of perovskite-based X-ray detectors. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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25 pages, 9964 KiB

Open AccessReview

Multi-Color Light-Emitting Diodes

by Su Ma, Yawei Qi, Ge Mu, Menglu Chen and Xin Tang

Coatings 2023, 13(1), 182; https://doi.org/10.3390/coatings13010182 - 13 Jan 2023

Cited by 7 | Viewed by 3152

Abstract

Multi-color light-emitting diodes (LEDs) with various advantages of color tunability, self-luminescence, wide viewing angles, high color contrast, low power consumption, and flexibility provide a wide range of applications including full-color display, augmented reality/virtual reality technology, and wearable healthcare systems. In this review, we [...] Read more.

Multi-color light-emitting diodes (LEDs) with various advantages of color tunability, self-luminescence, wide viewing angles, high color contrast, low power consumption, and flexibility provide a wide range of applications including full-color display, augmented reality/virtual reality technology, and wearable healthcare systems. In this review, we introduce three main types of multi-color LEDs: the organic LED, colloidal quantum dots (CQDs) LED, and CQD–organic hybrid LED. Various strategies for realizing multi-color LEDs are discussed including red, green, and blue sub-pixel side-by-side arrangement; vertically stacked LED unit configuration; and stacked emitter layers in a single LED. Finally, according to their status and challenges, we present an outlook of multi-color devices. We hope this review can inspire researchers and make a contribution to the further improvement of multi-color LED technology. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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10 pages, 2117 KiB

Open AccessReview

CMOS-Compatible Optoelectronic Imagers

by Cheng Bi and Yanfei Liu

Coatings 2022, 12(11), 1609; https://doi.org/10.3390/coatings12111609 - 22 Oct 2022

Cited by 1 | Viewed by 1375

Abstract

Silicon-based complementary metal oxide semiconductors have revolutionized the field of imaging, especially infrared imaging. Infrared focal plane array imagers are widely applied to night vision, haze imaging, food selection, semiconductor detection, and atmospheric pollutant detection. Over the past several decades, the CMOS integrated [...] Read more.

Silicon-based complementary metal oxide semiconductors have revolutionized the field of imaging, especially infrared imaging. Infrared focal plane array imagers are widely applied to night vision, haze imaging, food selection, semiconductor detection, and atmospheric pollutant detection. Over the past several decades, the CMOS integrated circuits modified by traditional bulk semiconductor materials as sensitivity sensors for optoelectronic imagers have been used for infrared imaging. However, traditional bulk semiconductor material-based infrared imagers are synthesized by complicated molecular beam epitaxy, and they are generally coupled with expensive flip-chip-integrated circuits. Hence, high costs and complicated fabrication processes limit the development and popularization of infrared imagers. Emerging materials, such as inorganic–organic metal halide perovskites, organic polymers, and colloidal quantum dots, have become the current focus point for preparing CMOS-compatible optoelectronic imagers, as they can effectively decrease costs. However, these emerging materials also have some problems in coupling with readout integrated circuits and uniformity, which can influence the quality of imagers. The method regarding coupling processes may become a key point for future research directions. In the current review, recent research progress on emerging materials for infrared imagers is summarized. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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29 pages, 5239 KiB

Open AccessReview

Room-Temperature Infrared Photodetectors with Zero-Dimensional and New Two-Dimensional Materials

by Taipeng Li, Xin Tang and Menglu Chen

Coatings 2022, 12(5), 609; https://doi.org/10.3390/coatings12050609 - 29 Apr 2022

Cited by 4 | Viewed by 2892

Abstract

Infrared photodetectors have received much attention for several decades due to their broad applications in the military, science, and daily life. However, for achieving an ideal signal-to-noise ratio and a very fast response, cooling is necessary in those devices, which makes them bulky [...] Read more.

Infrared photodetectors have received much attention for several decades due to their broad applications in the military, science, and daily life. However, for achieving an ideal signal-to-noise ratio and a very fast response, cooling is necessary in those devices, which makes them bulky and costly. Thus, room-temperature infrared photodetectors have emerged as a hot research direction. Novel low-dimensional materials with their easy fabrication and excellent photoelectronic properties provide a possible solution for room-temperature infrared photodetectors. This review aims to summarize the preparation methods and characterization of several low-dimensional materials (PbS, PbSe and HgTe, new two-dimensional materials) with great concern and the room-temperature infrared photodetectors based on them. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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20 pages, 4145 KiB

Open AccessReview

Infrared-to-Visible Upconversion Devices

by Tianyu Rao, Menglu Chen, Ge Mu and Xin Tang

Coatings 2022, 12(4), 456; https://doi.org/10.3390/coatings12040456 - 27 Mar 2022

Cited by 11 | Viewed by 5245

Abstract

Infrared imaging plays remarkable roles in various fields including military, biomedicine, aerospace, and artificial intelligence. However, traditional infrared imaging systems have plenty of disadvantages such as large volume, high cost, and complex fabrication process. Emerging infrared upconversion imaging devices can directly convert low-energy [...] Read more.

Infrared imaging plays remarkable roles in various fields including military, biomedicine, aerospace, and artificial intelligence. However, traditional infrared imaging systems have plenty of disadvantages such as large volume, high cost, and complex fabrication process. Emerging infrared upconversion imaging devices can directly convert low-energy infrared photons into high-energy visible light photons, thus they are promising to accomplish pixel-less high-resolution infrared imaging at low cost. In this paper, recent advances and progress of infrared-to-visible upconversion devices are summarized. We further offer the main limitations of upconversion technology and the challenges that need to be addressed for the future development of infrared upconverters. Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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13 pages, 2336 KiB

Open AccessReview

Advances of Sensitive Infrared Detectors with HgTe Colloidal Quantum Dots

by Shuo Zhang, Yao Hu and Qun Hao

Coatings 2020, 10(8), 760; https://doi.org/10.3390/coatings10080760 - 4 Aug 2020

Cited by 12 | Viewed by 4645

Abstract

The application of infrared detectors based on epitaxially grown semiconductors such as HgCdTe, InSb and InGaAs is limited by their high cost and difficulty in raising operating temperature. The development of infrared detectors depends on cheaper materials with high carrier mobility, tunable spectral [...] Read more.

The application of infrared detectors based on epitaxially grown semiconductors such as HgCdTe, InSb and InGaAs is limited by their high cost and difficulty in raising operating temperature. The development of infrared detectors depends on cheaper materials with high carrier mobility, tunable spectral response and compatibility with large-scale semiconductor processes. In recent years, the appearance of mercury telluride colloidal quantum dots (HgTe CQDs) provided a new choice for infrared detection and had attracted wide attention due to their excellent optical properties, solubility processability, mechanical flexibility and size-tunable absorption features. In this review, we summarized the recent progress of HgTe CQDs based infrared detectors, including synthesis, device physics, photodetection mechanism, multi-spectral imaging and focal plane array (FPA). Full article

(This article belongs to the Special Issue Application of Advanced Quantum Dots Films in Optoelectronics)

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