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New Advances in Novel Optical Materials and Devices
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New Advances in Novel Optical Materials and Devices

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Engineering for Energy Harvesting, Conversion, and Storage".

Deadline for manuscript submissions: 10 September 2024 | Viewed by 18921

Special Issue Editor

Dr. Alexandre Botas

E-Mail Website
Guest Editor
i3N, Department of Physics, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
Interests: photoluminescence; nanothermometry; hyperspectral microscopy

Special Issue Information

Dear Colleagues,

The optical materials and devices field continues to grow and plays a key role in new developments in areas such as biomedical devices, imaging, optical communication networks, optical storage media, and photovoltaics. The research activities in these areas require the use and control of electromagnetic radiation in the ultraviolet, visible, or infrared spectral regions, and optical materials and devices are tools that can perform such functions. Examples of optical materials include impurity-doped dielectric crystals, ceramics, glasses, polymers, rare-earth doped materials, and nano-based composites. These material are used for several applications: to fabricate devices with specific transmission, reflection, and absorption properties; to transmit information; and for sensing applications and energy conversion, just to name a few. Understanding the properties of these material is of major relevance since it will allow us to modify them in order to improve their performance and will allow the development of new applications. We are pleased to invite you to submit original research articles and review papers within the scope of the surface and interface science and engineering, representing theme of this Special Issue: “New Frontier in Novel Optical Materials and Devices”.

Research areas may include (but are not limited to) the following:

  • Thin and thick films for optical devices;
  • Characterization techniques for optical materials and devices;
  • Dyes, pigments and their intermediates with application in optical materials and devices;
  • Surface science applied to optical materials and devices;
  • Fundamental and functional properties of surface and interfaces applied to optical materials and devices;
  • Theoretical and computational modeling of surfaces and interfaces applied to optical materials and devices.

We look forward to receiving your contributions.

Dr. Alexandre Botas
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • optical materials
  • optical devices
  • luminescence
  • light emission
  • thin and thick films

Published Papers (13 papers)

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Editorial

Jump to: Research, Review

2 pages, 178 KiB  
Editorial
New Frontiers in Novel Optical Materials and Devices
by Alexandre M. P. Botas
Coatings 2022, 12(6), 856; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12060856 - 17 Jun 2022
Cited by 5 | Viewed by 1415
Abstract
Optical materials can be defined as materials that are used to alter and control electromagnetic radiation in the ultraviolet, visible or infrared spectral regions [...] Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)

Research

Jump to: Editorial, Review

16 pages, 5211 KiB  
Article
Photocatalytic Activities of Methylene Blue Using ZrO2 Thin Films at Different Annealing Temperatures
by Yuliana de Jesús Acosta-Silva, Salvador Gallardo-Hernández, Sandra Rivas, Fabricio Espejel-Ayala and Arturo Méndez-López
Coatings 2024, 14(5), 537; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings14050537 - 26 Apr 2024
Viewed by 332
Abstract
Tetragonal ZrO2, synthesized by the sol–gel method and dip-coating technique, was found to be photocatalytically active for the degradation of methylene blue. The ZrO2 thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning [...] Read more.
Tetragonal ZrO2, synthesized by the sol–gel method and dip-coating technique, was found to be photocatalytically active for the degradation of methylene blue. The ZrO2 thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV-vis spectroscopy. The photocatalytic degradation of methylene blue was carried out with this material. We identified the tetragonal phase in ZrO2 thin film at different annealing temperatures from 400 °C to 550 °C. The XRD study indicated that the films were monocrystalline in nature with preferred grain orientation along (011) plane and exhibited a tetragonal crystal structure. The crystallite size of the films increased with increasing annealing temperature. FTIR explained the bonding nature and confirmed the formation of the composite. UV-Vis showed the optical absorbance was high in the visible region and the optical band gap value increased with annealing temperature. The photocatalytic experimental results revealed that ZrO2 thin films degraded MB by 20%, 24%, 29%, and 36%, with annealing temperatures of 400 °C at 550 °C for 10 h, respectively. Our results provide useful insights into the development of photocatalytic materials and degradation of methylene blue. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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13 pages, 3459 KiB  
Article
MACl-Induced Controlled Crystallization in Sequentially Deposited Perovskites for High-Efficiency and Stable Perovskite Solar Cells
by Qiang Ma, Yulong Zhang, Chaoqun Lu, Rui Zhang, Xinjie Wang, Weijia Zhang and Zhaoyi Jiang
Coatings 2023, 13(11), 1885; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13111885 - 02 Nov 2023
Cited by 1 | Viewed by 916
Abstract
Perovskite solar cells are attracting more and more attention due to their higher absorption and low cost. However, fabricating the perovskite film with high crystallinity and ideal morphology, which presents large-size and uniform particles with fewer grain boundaries, still needs further improvement. Herein, [...] Read more.
Perovskite solar cells are attracting more and more attention due to their higher absorption and low cost. However, fabricating the perovskite film with high crystallinity and ideal morphology, which presents large-size and uniform particles with fewer grain boundaries, still needs further improvement. Herein, we introduce MAPbCl3 crystals into the PbI2 film in the sequential deposition process, which obtained the controlled crystallization in perovskite films. The perovskite films induced by MAPbCl3 have stronger crystallinity, fewer defect states, and larger grain size, reducing carrier recombination and improving carrier transfer. The optimized perovskite solar cell (PSC) has achieved a power conversion efficiency of 20.97%. Furthermore, the stability of PSCs has also been enhanced due to the reduced grain boundaries impeding moisture diffusion. This strategy can be applied in other solution-based fabrication processes to improve the photovoltaic performance of PSCs. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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13 pages, 25855 KiB  
Article
Study of the Application of Recycled Gold Nanoparticles in Coatings for Eyewear Lenses
by Peter Majerič, Djuro Koruga, Zorana Njegovan, Žiga Jelen, Tilen Švarc, Andrej Horvat and Rebeka Rudolf
Coatings 2023, 13(10), 1666; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13101666 - 22 Sep 2023
Viewed by 761
Abstract
The surface plasmon resonance of gold nanoparticles causes visible light absorption and scattering effects that may be used in optical coatings for eliminating blue light emission from display monitors, for blocking UV light, and for decorative applications. This study examines the achievement of [...] Read more.
The surface plasmon resonance of gold nanoparticles causes visible light absorption and scattering effects that may be used in optical coatings for eliminating blue light emission from display monitors, for blocking UV light, and for decorative applications. This study examines the achievement of functional properties provided by gold nanoparticles in a commercially established C60 fullerene-coated eyewear product. The gold nanoparticles used were sourced from recycling rapid lateral flow tests (LFIA), which use gold nanoparticles as test markers. After the gold’s recovery, Ultrasonic Spray Pyrolysis (USP) with freeze-drying was used for the synthesis of new gold nanoparticles, to be used in optical coatings. The gold nanoparticles were examined with SEM, TEM, DLS, zeta potential, BET, and Vis-NIR for characterising their shapes and sizes, as is required for determination of the surface plasmon resonance effect. After applying the newly produced gold nanoparticles with fullerene C60 in a combined coating for eyewear lenses, the absorption and transmission of the lenses were determined for establishing changes in the coating’s functionality. The results show that enhancing the fullerene C60 coating with gold nanoparticles improves light absorption and reflectance for blue and UV light further, which may be evaluated as beneficial for the eyewear user, as the reduction in eye strain is increased due to the coating. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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12 pages, 9747 KiB  
Article
Four-Polarisation Camera for Anisotropy Mapping at Three Orientations: Micro-Grain of Olivine
by Shuji Kamegaki, Daniel Smith, Meguya Ryu, Soon Hock Ng, Hsin-Hui Huang, Pegah Maasoumi, Jitraporn Vongsvivut, Daniel Moraru, Tomas Katkus, Saulius Juodkazis and Junko Morikawa
Coatings 2023, 13(9), 1640; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13091640 - 18 Sep 2023
Cited by 1 | Viewed by 1505
Abstract
A four-polarisation camera was used to map the absorbance of olivine micro-grains before and after high-temperature annealing (HTA). It is shown that HTA of olivine xenoliths at above 1200 °C in O2 flow makes them magnetised. Different modes of operation of [...] Read more.
A four-polarisation camera was used to map the absorbance of olivine micro-grains before and after high-temperature annealing (HTA). It is shown that HTA of olivine xenoliths at above 1200 °C in O2 flow makes them magnetised. Different modes of operation of the polariscope with polarisation control before and after the sample in transmission and reflection modes were used. The reflection type was assembled for non-transparent samples of olivine after HTA. The sample for optical observation in transmission was placed on an achromatic, plastic, quarter-wavelength waveplate as a sample holder. Inspection of the sample’s birefringence (retardance), as well as absorbance, was undertaken. The best fit for the transmitted intensity or transmittance T (hence, absorbance A=−log10T) is obtainable using a simple best fit with only three orientations (from the four orientations measured by the camera). When the intensity of transmitted light at one of the orientations is very low due to a cross-polarised condition (polariser–analyser arrangement), the three-point fit can be used. The three-point fit in transmission and reflection modes was validated for T(θ)=Amp×cos(2θ−2θshift)+offset, where the amplitude Amp, offset offset, and orientation azimuth θshift were extracted for each pixel via the best fit. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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10 pages, 3111 KiB  
Article
Visible Light–Near-Infrared Photodetection on Cys-MoO3−x Nanoparticles for Photothermal Therapy against Papillary Thyroid Carcinoma
by Jinhuan Chen, Xian Liu, Xin Zeng, Ming Yang and Liang Xie
Coatings 2023, 13(9), 1552; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13091552 - 05 Sep 2023
Cited by 1 | Viewed by 996
Abstract
The excellent performance of semiconductor nanocrystals as sensitizers for photothermal therapy (PTT) has attracted the attention of many researchers; however, they are hindered by limited bandwidth and complex synthesis. To overcome these limitations, starting with an initial determination of photothermal conductivity, we synthesized [...] Read more.
The excellent performance of semiconductor nanocrystals as sensitizers for photothermal therapy (PTT) has attracted the attention of many researchers; however, they are hindered by limited bandwidth and complex synthesis. To overcome these limitations, starting with an initial determination of photothermal conductivity, we synthesized and designed molybdenum and Cys-MoO3−x nanoparticles (NPs) for use in the minimally invasive treatment of papillary thyroid carcinoma (PTC), as the NPs are coated only with cysteine molecules. The obtained Cys-MoO2 NPs were used as a PTT reaction drug for topical application to PTC cells. The use of near-infrared photoconductive PTT in combination with low-toxicity biological chemotherapy reached a 90% efficacy for cancer treatment in vitro. The conducted experiments intuitively demonstrate that non-toxic Cys-MoO2 NPs are lethal to the cancer cells under visual (VL, 405 nm) and near-infrared (NIR, 808 nm) laser irradiation and can be precisely controlled. Therefore, this study provides a powerful, safe, and easily modified NP platform for photo-triggered PTC elimination with broad application prospects. Assessment of the ideal damage range indicates a high degree of controllability, allowing the tumor to be precisely targeted while minimizing damage to the surrounding healthy tissue. In conclusion, this study provides a convenient, safe, and powerful NP platform for the near-infrared photo-controlled PTT of PTC cells, which has broad application prospects for the elimination of PTC and other types of cancer. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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11 pages, 3991 KiB  
Article
Luminescent Properties of Polycarbonate Methacrylates Containing Organic Fluorescent Dyad
by Irina A. Matveeva, Valentina T. Shashkova, Alexander V. Lyubimov, Galina V. Lyubimova, Liubov S. Koltsova, Andrey I. Shienok, Natalia L. Zaichenko and Peter P. Levin
Coatings 2023, 13(6), 1071; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13061071 - 09 Jun 2023
Viewed by 870
Abstract
The luminescent properties of photocured aliphatic and aromatic network polycarbonate methacrylates, containing organic fluorescent dyad, have been studied. The dyad molecule includes two photosensitive fragments—tetraarylimidazole with a hydroxyl group and azomethinocoumarin—in each of which excited state intramolecular proton transfer (ESIPT) occurs, leading to [...] Read more.
The luminescent properties of photocured aliphatic and aromatic network polycarbonate methacrylates, containing organic fluorescent dyad, have been studied. The dyad molecule includes two photosensitive fragments—tetraarylimidazole with a hydroxyl group and azomethinocoumarin—in each of which excited state intramolecular proton transfer (ESIPT) occurs, leading to the appearance of two emissions: blue (450 nm) and green (535 nm). It was established that the ratio of the intensities of these emissions depends very significantly on the excitation wavelength, as well as on the length, flexibility and polarity of the matrix oligomeric bridges. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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23 pages, 4177 KiB  
Article
Investigation of Structural and Optical Characteristics of Biopolymer Composites Based on Polyvinyl Alcohol Inserted with PbS Nanoparticles
by Ari H. A. Darwesh, Pshko A. Mohammed, Soran M. Mamand, Sarkawt A. Hussen, Shujahadeen B. Aziz, Mohamad A. Brza, Ranjdar M. Abdullah and Wrya O. Karim
Coatings 2023, 13(3), 578; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13030578 - 07 Mar 2023
Cited by 9 | Viewed by 2106
Abstract
The film casting method is implemented to synthesize a series of films consisting of polyvinyl alcohol (PVA) films and 4 wt%, 8 wt%, and 12 wt% lead sulfide (PbS) nanoparticles (NPs). X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Ultraviolet-visible (UV-vis) spectroscopy were [...] Read more.
The film casting method is implemented to synthesize a series of films consisting of polyvinyl alcohol (PVA) films and 4 wt%, 8 wt%, and 12 wt% lead sulfide (PbS) nanoparticles (NPs). X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Ultraviolet-visible (UV-vis) spectroscopy were used to ensure the impact of PbS loading on PVA properties, particularly optical ones. The FTIR results show a decrease in the intensity for all the bands and the XRD results show different features for the composites from that of the pure PVA. The optical properties, including optical transmission, surface reflection, and absorption, were investigated. Additionally, the significant optical parameters, for instance, the dielectric nature and refractive index of the films, were analyzed. The findings have shown that PbS NPs in the PVA films decrease UV and visible transmission through polymer composites and increase their ability to reflect the incident light. Tauc’s equation is applied to determine the optical bandgap energy (Eg) and verify whether it is direct or indirect. Using the relation between photon energy and optical dielectric loss, the Eg was measured and the type of electron transition was measured, which eases the exponent value (𝜸) specification from Tauc’s method. The Eg decreases from 6.3 eV to 5.25 eV when PbS NPs are added. The refractive index is improved from 1.27 to 2.16 for the polymer nanocomposite (NCPs) film with optimum PbS NPs. Then, the Wemple–DiDomenico model corresponding to a single oscillator is applied to the dispersive medium to determine the refractive index dispersion. Both the dispersive energy (Ed) and single-oscillator energy (Eo) are evaluated accurately. Moreover, the variation of both real and imaginary parts of the dielectric constant of polymer films were studied. Finally the optical parameters such as charge density, dielectric constant at high frequencies, optical mobility (µ), angular frequency (ωp), optical resistivity (ρ), and relaxation time (τ) of electrons are shown quantitatively. The ωp of the electron is increased from 1.06 × 1029 to 81.5 × 1029 Hz when the PbS NPs is added. The µ of the electrons is also increased from 4.85 to 6.22 cm2/(V·s) by adding the PbS NP. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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16 pages, 3709 KiB  
Article
Enhanced Optically–Excited THz Wave Emission by GaAs Coated with a Rough ITO Thin Film
by Anup Kumar Sahoo, Shi-Ying Kang, Peichen Yu and Ci-Ling Pan
Coatings 2023, 13(2), 461; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13020461 - 17 Feb 2023
Cited by 1 | Viewed by 1526
Abstract
In this study, we report enhancement of terahertz (THz) radiation with indium-tin-oxide (ITO) thin-film deposited on semi-insulating gallium arsenide substrate (SI-GaAs). The amplitude of THz emission from both ITO/SI-GaAs and bare SI-GaAs substrate as a function of optical pump (i) incident angle, (ii) [...] Read more.
In this study, we report enhancement of terahertz (THz) radiation with indium-tin-oxide (ITO) thin-film deposited on semi-insulating gallium arsenide substrate (SI-GaAs). The amplitude of THz emission from both ITO/SI-GaAs and bare SI-GaAs substrate as a function of optical pump (i) incident angle, (ii) polarization angle, and (iii) power were investigated. The enhancement of peak amplitude of a THz pulse transmitted through the ITO/SI-GaAs sample in comparison to bare SI-GaAs substrate varied from 100% to 0% when the pump incidence angle changed from 0° to 50°. The maximum enhancement ratio of peak amplitude for a coated sample relative to the bare substrate is approximately up to 2.5 times at the minimum pump intensity of 3.6 TW/m2 and gradually decreased to one at the maximum pump intensity of 20 TW/m2. From outcomes of these studies, together with data on surface and material characterization of the samples, we show that THz emission originates from the ITO/GaAs interfaces. Further, both interface-field-induced transient current and field-induced optical rectification contribute to the observed THz signal. Observed enhancement was tentatively attributed to surface-plasmon-induced local field enhancement, coupled with constructive interference of forward and retro-reflected backward THz emission from the ITO/GaAs interfaces. The polarity-flip reported previously for very thin Au-coated GaAs was not observed. This was explained by the wide-bandgap, transparency and lower free carriers of ITO. For best results, the incident angle should be in the range of 0 to 30° and the incident polarization should be 0 to 45°. We further predict that the ITO thin film of suitable thickness or with engineered nanostructures, post-annealed under optimum conditions may lead to further enhancement of THz radiation from ITO-coated semiconductor surfaces. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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15 pages, 2369 KiB  
Article
A Model Surface for Calculating the Reflectance of Smooth and Rough Aluminum Layers in the Vacuum Ultraviolet Spectral Range
by Olaf Stenzel, Steffen Wilbrandt, Jian-Ying He, Sven Stempfhuber, Sven Schröder and Andreas Tünnermann
Coatings 2023, 13(1), 122; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13010122 - 09 Jan 2023
Cited by 3 | Viewed by 1511
Abstract
We present a systematic approach to calculating the reflectance of aluminum thin films. In our approach, the rough aluminum surface is modelled as a square array of submicrometer-sized oblate cylinders. The focus of the study is on the vacuum ultraviolet (VUV) spectral range, [...] Read more.
We present a systematic approach to calculating the reflectance of aluminum thin films. In our approach, the rough aluminum surface is modelled as a square array of submicrometer-sized oblate cylinders. The focus of the study is on the vacuum ultraviolet (VUV) spectral range, with wavelengths ranging from 120 nm to 200 nm. The VUV reflectance of aluminum films is calculated by using the rigorous coupled wave approach in order to take the surface roughness of aluminum into account. The modelled reflectance spectra are compared to experimental data from unprotected and protected aluminum films. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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20 pages, 5424 KiB  
Article
Application of the Holomorphic Tauc-Lorentz-Urbach Function to Extract the Optical Constants of Amorphous Semiconductor Thin Films
by Manuel Ballester, Marcos García, Almudena P. Márquez, Eduardo Blanco, Susana M. Fernández, Dorian Minkov, Aggelos K. Katsaggelos, Oliver Cossairt, Florian Willomitzer and Emilio Márquez
Coatings 2022, 12(10), 1549; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12101549 - 14 Oct 2022
Cited by 4 | Viewed by 2311
Abstract
The Tauc–Lorentz–Urbach (TLU) dispersion model allows us to build a dielectric function from only a few parameters. However, this dielectric function is non-analytic and presents some mathematical drawbacks. As a consequence of this issue, the model becomes inaccurate. In the present work, we [...] Read more.
The Tauc–Lorentz–Urbach (TLU) dispersion model allows us to build a dielectric function from only a few parameters. However, this dielectric function is non-analytic and presents some mathematical drawbacks. As a consequence of this issue, the model becomes inaccurate. In the present work, we will adopt a procedure to conveniently transform the TLU model into a self-consistent dispersion model. The transformation involves the integration of the original TLU imaginary dielectric function ϵ2 by using a Lorentzian-type function of semi-width, Γ. This novel model is analytic and obeys the other necessary mathematical requirements of the optical constants of solid-state materials. The main difference with the non-analytic TLU model occurs at values of the photon energy near or lower than that of the bandgap energy (within the Urbach absorption region). In particular, this new model allows us to reliably extend the optical characterization of amorphous-semiconductor thin films within the limit to zero photon energy. To the best of our knowledge, this is the first time that the analytic TLU model has been successfully used to accurately determine the optical constants of unhydrogenated a-Si films using only their normal-incidence transmission spectra. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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Review

Jump to: Editorial, Research

24 pages, 5822 KiB  
Review
Multiplier Effects of Photodetectors—Source of Gain
by Ming Yang, Haoliang Chang, Jinhuan Chen and Xinyu Zhu
Coatings 2023, 13(6), 1088; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13061088 - 12 Jun 2023
Cited by 1 | Viewed by 1687
Abstract
A photodetector is a type of optoelectronic device with excellent photoelectric conversion abilities, which has especially important applications in many fields such as optical communication, image sensing, aerospace/environmental detection, and military safety. Among these applications, the multiplier effect of optoelectronic devices has been [...] Read more.
A photodetector is a type of optoelectronic device with excellent photoelectric conversion abilities, which has especially important applications in many fields such as optical communication, image sensing, aerospace/environmental detection, and military safety. Among these applications, the multiplier effect of optoelectronic devices has been widely explored because photodetectors can convert a very weak optical signal into electrical signal output and offer amazing electron multiplication abilities. To date, hundreds of multiplier effects of photodetectors have been reported. However, there are few reviews on the multiplier effects of such devices. Here, a review of the multiplier effects of photodetectors covering detection spectra from ultraviolet to infrared is presented, including photodetectors based on inorganic materials, organic materials, and organic/inorganic materials. First, we provide brief insights into the detection mechanisms of multiplier effects of photodetectors and introduce the merits that represent key factors for a reasonable comparison of different photodetectors. Then, the multiplier effect on different types of material photodetectors is reviewed. Notably, we summarize the optimization directions of the performance of the multiplier photodetectors, including improving the external quantum efficiency, reducing the dark current, and increasing the response speed and spectral regulation. Finally, an outlook is delivered, the challenges and future directions are discussed, and general advice for designing and realizing novel high-performance photodetectors with multiplier effects is given to provide a guideline for the future development of this fast-developing field. The bottlenecks of existing multiplier technology are also analyzed, which has strong reference significance for the future development of this field. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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18 pages, 3847 KiB  
Review
Bi-Substituted Ferrite Garnet Type Magneto-Optic Materials Studied at ESRI Nano-Fabrication Laboratories, ECU, Australia
by Mohammad Nur-E-Alam, Mikhail Vasiliev and Kamal Alameh
Coatings 2022, 12(10), 1471; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12101471 - 05 Oct 2022
Cited by 2 | Viewed by 1986
Abstract
Since 2007, at the Electron Science Research Institute (ESRI) nano-fabrication laboratories, Edith Cowan University, Australia, we have devoted research efforts to the synthesis and characterization of bismuth-containing ferrite-garnet-type thin-film magneto-optic (MO) materials of different compositions. We report on the growth and characteristics of [...] Read more.
Since 2007, at the Electron Science Research Institute (ESRI) nano-fabrication laboratories, Edith Cowan University, Australia, we have devoted research efforts to the synthesis and characterization of bismuth-containing ferrite-garnet-type thin-film magneto-optic (MO) materials of different compositions. We report on the growth and characteristics of radio frequency (RF) magnetron sputtered bismuth-substituted iron-garnet thin films. We study the process parameters associated with the RF magnetron sputter deposition technique and investigate the results of optimizing process parameters. To achieve the best MO properties, we employ a few unique techniques, such as co-sputtered nanocomposite films and all-garnet multilayer structures, as well as the application of oxygen plasma treatment to amorphous garnet layers immediately following the deposition process. We demonstrated a remarkable enhancement in the MO properties of Bi-containing ferrite-type garnet thin-film materials, including record-high MO figures of merit and improved conventional and unconventional hysteresis loops of Faraday rotation. Previously unpublished research results on the forward-looking applications of magnetic garnet coatings applied to microparticles of advanced luminescent materials are reported. In the context of developing the next-generation ultra-fast optoelectronic devices, such as light intensity switches and modulators, high-speed flat panel displays, and high-sensitivity sensors, it is important to consider the desirable optical, magnetic, and magneto-optic properties that are found in highly bismuth-substituted iron garnet thin-film materials of various composition types. Full article
(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)
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