scholarly journals Recent Advances in Fabrication of Flexible, Thermochromic Vanadium Dioxide Films for Smart Windows

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2674
Author(s):  
Jongbae Kim ◽  
Taejong Paik
Keyword(s):  
Thin Films ◽  
Energy Saving ◽  
Near Infrared ◽  
Solar Spectrum ◽  
Smart Windows ◽  
Space Group ◽  
Practical Applications ◽  
Flexible Polymer ◽  
Recent Advances ◽  
Potential Applications

Monoclinic-phase VO2 (VO2(M)) has been extensively studied for use in energy-saving smart windows owing to its reversible insulator–metal transition property. At the critical temperature (Tc = 68 °C), the insulating VO2(M) (space group P21/c) is transformed into metallic rutile VO2 (VO2(R) space group P42/mnm). VO2(M) exhibits high transmittance in the near-infrared (NIR) wavelength; however, the NIR transmittance decreases significantly after phase transition into VO2(R) at a higher Tc, which obstructs the infrared radiation in the solar spectrum and aids in managing the indoor temperature without requiring an external power supply. Recently, the fabrication of flexible thermochromic VO2(M) thin films has also attracted considerable attention. These flexible films exhibit considerable potential for practical applications because they can be promptly applied to windows in existing buildings and easily integrated into curved surfaces, such as windshields and other automotive windows. Furthermore, flexible VO2(M) thin films fabricated on microscales are potentially applicable in optical actuators and switches. However, most of the existing fabrication methods of phase-pure VO2(M) thin films involve chamber-based deposition, which typically require a high-temperature deposition or calcination process. In this case, flexible polymer substrates cannot be used owing to the low-thermal-resistance condition in the process, which limits the utilization of flexible smart windows in several emerging applications. In this review, we focus on recent advances in the fabrication methods of flexible thermochromic VO2(M) thin films using vacuum deposition methods and solution-based processes and discuss the optical properties of these flexible VO2(M) thin films for potential applications in energy-saving smart windows and several other emerging technologies.

scholarly journals Temperature-dependent optical and vibrational properties of PtSe2 thin films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Desman P. Gulo ◽  
Han Yeh ◽  
Wen-Hao Chang ◽  
Hsiang-Lin Liu
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Room Temperature ◽  
Near Infrared ◽  
Technological Development ◽  
Phonon Modes ◽  
Research Attention ◽  
Practical Applications ◽  
Infrared Frequency Range ◽  
Indirect Band Gap

Abstract PtSe2 has received substantial research attention because of its intriguing physical properties and potential practical applications. In this paper, we investigated the optical properties of bilayer and multilayer PtSe2 thin films through spectroscopic ellipsometry over a spectral range of 0.73–6.42 eV and at temperatures between 4.5 and 500 K. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 1000 nm and approached a constant value in the near-infrared frequency range. The thermo-optic coefficients of bilayer and multilayer PtSe2 thin films were (4.31 ± 0.04) × 10−4/K and (–9.20 ± 0.03) × 10−4/K at a wavelength of 1200 nm. Analysis of the optical absorption spectrum at room temperature confirmed that bilayer PtSe2 thin films had an indirect band gap of approximately 0.75 ± 0.01 eV, whereas multilayer PtSe2 thin films exhibited semimetal behavior. The band gap of bilayer PtSe2 thin films increased to 0.83 ± 0.01 eV at 4.5 K because of the suppression of electron–phonon interactions. Furthermore, the frequency shifts of Raman-active Eg and A1g phonon modes of both thin films in the temperature range between 10 and 500 K accorded with the predictions of the anharmonic model. These results provide basic information for the technological development of PtSe2-based optoelectronic and photonic devices at various temperatures.

scholarly journals ITO@SiO2 and ITO@{M6Br12}@SiO2 (M = Nb, Ta) Nanocomposite Films for Ultraviolet-Near Infrared Shielding

2019 ◽  
Author(s):  
Wanghui Chen ◽  
Ngan Thikimngan Nguyen ◽  
Maxence Wilmet ◽  
Noee Dumait ◽  
Ourania Makrygenni ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Saving ◽  
Near Infrared ◽  
Nanocomposite Films

Transparent optical thin films for energy saving application have recently gained substantial prominence for functional window processes. In this study, highly visible transparent nanocomposite films with ultraviolet (UV) and near-infrared...

scholarly journals Atomic Layer-Deposited Al-Doped ZnO Thin Films for Display Applications

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 539 ◽  
Author(s):  
Dimitre Dimitrov ◽  
Che-Liang Tsai ◽  
Stefan Petrov ◽  
Vera Marinova ◽  
Dimitrina Petrova ◽  
...  
Keyword(s):  
Thin Films ◽  
Liquid Crystal ◽  
Indium Tin Oxide ◽  
Near Infrared ◽  
Atomic Layer ◽  
Optical Transmittance ◽  
Flexible Polymer ◽  
Polymer Dispersed ◽  
Infrared Spectral ◽  
Aluminum Doped Zinc Oxide

The integration of high uniformity, conformal and compact transparent conductive layers into next generation indium tin oxide (ITO)-free optoelectronics, including wearable and bendable structures, is a huge challenge. In this study, we demonstrate the transparent and conductive functionality of aluminum-doped zinc oxide (AZO) thin films deposited on glass as well as on polyethylene terephthalate (PET) flexible substrates by using an atomic layer deposition (ALD) technique. AZO thin films possess high optical transmittance at visible and near-infrared spectral range and electrical properties competitive to commercial ITO layers. AZO layers deposited on flexible PET substrates demonstrate stable sheet resistance over 1000 bending cycles. Based on the performed optical and electrical characterizations, several applications of ALD AZO as transparent conductive layers are shown—AZO/glass-supported liquid crystal (LC) display and AZO/PET-based flexible polymer-dispersed liquid crystal (PDLC) devices.

scholarly journals Energy-Efficient Smart Window Based on Thermochromic Hydrogel with Ultrahigh Visible Transparency and Unprecedented Infrared Transmittance Modulation

2021 ◽  
Author(s):  
Rong Zhang ◽  
Bo Xiang ◽  
Min Feng ◽  
Liru Xia ◽  
Lei Xu ◽  
...  
Keyword(s):  
Energy Saving ◽  
Superior Performance ◽  
Significant Advance ◽  
Solar Modulation ◽  
Smart Window ◽  
Smart Windows ◽  
Responsive Materials ◽  
Infrared Transmittance ◽  
Potential Applications ◽  
Glass Panels

Abstract Both high visible transparency and strong solar modulating ability are highly required for energy-saving smart windows, but conventional responsive materials usually have low transparency and narrow solar transmittance range. Herein, we report a significant advance toward the design and fabrication of responsive smart windows by trapping novel V0.8W0.2O2@SiO2 doped poly(N-isopropyl acrylamide) (PNIPAm) thermochromic liquid hydrogel within two glass panels. The smart window is highly transparent to allow solar transmittance at low temperatures, while turns opaque automatically to cut off solar energy gain when exposed in sunlight. With a remarkably low content (1.0wt‰) of dopant, V0.8W0.2O2@SiO2/PNIPAm (VSP) hydrogels exhibit ultrahigh luminous transmittance Tlum of 92.48% and solar modulation ∆Tsol of 77.20%. The superior performance is mainly attributed to that V0.8W0.2O2@SiO2 doping induces PNIPAm particles’ size reduction and internal structure change. W-doping decreases the phase transition temperature (Tc) of VO2 from 68 ºC to ~30 ºC (close to the Tc of PNIPAm), contributing to an unprecedented infrared transmittance modulation. Especially, the smart window shows excellent energy-saving during daytime outdoor demonstrations where practically achievable cooling temperature reaches up to 15.1 ºC. In addition, the smart window exhibits outstanding stability, as embodied by unchanged optical performance even after 100 transparency-opaqueness reversible cycles. This new type of thermochromic hydrogel offering unique advantages of shape-independence, scalability together with soundproof functionality promises potential applications in energy-saving buildings and greenhouses.

Recent advances in triphenylamine-based electrochromic derivatives and polymers

2018 ◽  
Vol 9 (22) ◽  
pp. 3001-3018 ◽  
Author(s):  
Hung-Ju Yen ◽  
Guey-Sheng Liou
Keyword(s):  
Energy Consumption ◽  
Exponential Growth ◽  
Low Energy ◽  
Electrochromic Materials ◽  
Smart Windows ◽  
Recent Advances ◽  
Low Energy Consumption ◽  
Potential Applications

Triphenylamine-containing electrochromic materials with great potential applications in low energy-consumption displays, light-adapting mirrors in vehicles, and smart windows have experienced an exponential growth of research interests. In this review, the newly developed triphenylamine-based derivatives and polymers are reviewed and elaborated.

High thermochromic performance of Fe/Mg co-doped VO2 thin films for smart window applications

2018 ◽  
Vol 6 (24) ◽  
pp. 6502-6509 ◽  
Author(s):  
Chunhui Ji ◽  
Zhiming Wu ◽  
Lulu Lu ◽  
Xuefei Wu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
New Method ◽  
Smart Window ◽  
Smart Windows ◽  
Practical Applications ◽  
Co Doping ◽  
Window Applications ◽  
Vo2 Thin Films ◽  
First Time ◽  
Co Doped

A new method, Fe/Mg co-doping, is proposed for the first time to optimize thermochromic VO2 and the promising performance of VO2-based smart windows for practical applications is successfully achieved.

Biocatalysis of carboxylic acid reductases: phylogenesis, catalytic mechanism and potential applications

2018 ◽  
Vol 20 (4) ◽  
pp. 777-792 ◽  
Author(s):  
Ge Qu ◽  
Jinggong Guo ◽  
Dameng Yang ◽  
Zhoutong Sun
Keyword(s):  
Carboxylic Acid ◽  
Catalytic Mechanism ◽  
Practical Applications ◽  
Recent Advances ◽  
Potential Applications ◽  
Cascade Processes

Recent advances in carboxylic acid reductases and their practical applications in bio-cascade processes.

One-Step Hydrothermal Synthesis of (NH4)2V4O9 Thin Films Composed of Stacked Single-Crystal Nanosheets

2017 ◽  
Vol 863 ◽  
pp. 102-106
Author(s):  
Xue Mei Yang ◽  
Xiao Yu Zhou ◽  
Zhong Ping Liu ◽  
Lan Xiang Ji ◽  
Jian Guo Deng
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Band Gap ◽  
Oriented Attachment ◽  
Practical Applications ◽  
Crystal Growth Mechanism ◽  
Potential Applications ◽  
One Step ◽  
Vertically Aligned ◽  
Defect Densities

(NH4)2V4O9 thin films composed of vertically aligned single-crystal nanosheets were directly fabricated on quartz glass by a one-step hydrothermal method. In order to study the formation mechanism and to explore the potential applications of the thin films, process experiments were carried out and the band gap was analyzed. An oriented-attachment exfoliation–recrystallization–crystal growth mechanism was proposed for the formation of the (NH4)2V4O9 thin films. In addition, the band gap varied from 2.13 to 2.87 eV with variations in the thickness from 40.21 to 78.64 μm. The move of the band gap main due to the decreasing bond lengths and defect densities with increasing reaction time and which is significant for practical applications.

Two-Junction GaAs/Ge Cells With Three Terminals for PV and CPV Applications

2009 ◽  
Vol 1165 ◽  
Author(s):  
Mahieddine Emziane
Keyword(s):  
Power Output ◽  
Near Infrared ◽  
Incident Light ◽  
Solar Spectrum ◽  
Junction Device ◽  
High Power Output ◽  
Optimal Current ◽  
Simulated Concentration ◽  
Potential Applications ◽  
Double Junction

AbstractThe present investigation deals with a two-junction device having GaAs as the top cell and Ge for the bottom cell on a Ge substrate. Compared with the conventional two-terminal device configuration, three terminals avoid the loss due to current mismatching between the cells, and the resistance loss originating from the tunnel junction between the cells. Device structures were investigated and optimized with regard to the thicknesses and doping levels of both top and bottom active junctions that lead to the highest device performance. Due to the split of the incident solar spectrum between GaAs and Ge cells, the latter only receives the light to which the former is transparent (mainly in the near infrared) and therefore behaves differently from a single-junction Ge cell. Optimal current-voltage and power-voltage characteristics were generated for individual cells together with the corresponding device PV parameters. The predictions show that an extended spectral coverage is achieved leading to an enhanced overall power output from the devices. The potential applications of these devices in conventional as well as concentrator PV were assessed and discussed as a function of the simulated concentration ratio of the incident light under AM1.5 illumination conditions. We have shown that a relatively thin double-junction GaAs/Ge device can achieve a remarkably high power output.

scholarly journals Optically Active TiO2:Er Thin Films Deposited by Magnetron Sputtering

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4085
Author(s):  
Anna Kot ◽  
Marta Radecka ◽  
Dominik Dorosz ◽  
Katarzyna Zakrzewska
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Near Infrared ◽  
Hydrogen Generation ◽  
Solar Spectrum ◽  
Fundamental Absorption Edge ◽  
Optically Active ◽  
Photon Absorption ◽  
Light Spectrum ◽  
Tio2 Thin Films

Titanium dioxide photoanodes for hydrogen generation suffer from a profound mismatch between the optical absorption of TiO2 and the solar spectrum. To solve the problem of low solar-to-chemical efficiency, optically active materials are proposed. In this work, TiO2 thin films containing erbium were deposited by radio frequency RF magnetron sputtering under ultrahigh vacuum conditions UHV. Morphology, structural, optical and electronic properties were studied. TiO2:Er thin films are homogenous, with uniform distribution of Er ions and high transparency over the visible VIS range of the light spectrum. However, a profound 0.4 eV blue shift of the fundamental absorption edge with respect to undoped TiO2 was observed, which can be attributed either to the size effect due to amorphization of TiO2 host or to the onset of precipitation of Er2Ti2O7 nanocrystals. Near-infrared NIR to VIS up-conversion is demonstrated upon excitation at 980 nm, while strong green photoluminescence at 525 and 550 nm occurs upon photon absorption at 488 nm.

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