Effect of substrate temperature on the near-infrared shielding properties of WO3-x thin films deposited by RF magnetron sputtering

Nair, Anjana S.; S, Keerthana C.; Abraham, Jisha Elsa; George, Pranav; Joseph, Cyriac; Biju, P.R.; Unnikrishnan, N.V.; Saritha, A

doi:10.1016/j.vacuum.2022.111143

Cited by 14 publications

(8 citation statements)

References 53 publications

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“…where T is the transmittance value obtained from spectrophotometry and t is the thickness of the films obtained from ellipsometry [26]. A plot of the absorption coefficient vs wavelength shown in figure 4 elucidates the observed transmission spectrum.…”

Section: Resultsmentioning

confidence: 81%

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films

C S,

S Nair,

et al. 2024

Semicond. Sci. Technol.

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Gallium oxide (Ga2O3) is a transparent material with high absorption in the UVC region of the electromagnetic spectrum and hence is a very important candidate in the field of fabrication of short wavelength optical devices. A proper understanding about the different optical parameters is necessary for developing more efficient coatings and devices. In this work, changes in the optical behaviour of gallium oxide thin films due to post-deposition annealing (at temperatures 300 – 900°C) are discussed in detail. Structural, surface morphological and compositional modifications of the films are identified using the XRD, SEM and XPS techniques respectively. At 900°C, highly stable monoclinic β phase of Ga2O3 is obtained. The optical transmittance spectra acquired using UV-Vis spectroscopy indicate the improved UVC absorbance of the β-Ga2O3 films with excellent visible transmittance (>80%). Structural transformation from amorphous to crystalline β-Ga2O3 phase and the associated reduction in defect density is found to modify other optical attributes also, like bandgap energy, Urbach energy, dispersion parameters etc.

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Section: Resultsmentioning

confidence: 81%

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films

C S,

S Nair,

et al. 2024

Semicond. Sci. Technol.

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“…The most striking feature of our OMO-based T-OSCs is that we introduce WO 3 as an HTL and an antireflection layer, which has higher transparency than MoO 3 , an identical hole transport mechanism to MoO 3 , and a similar refractive index to MoO 3 . − As shown in the transmittance spectra of the WO 3 and MoO 3 thin films, the WO 3 film shows a higher transmittance than the MoO 3 film with an average visible transmittance (AVT) of 92.6%, which is higher than that of the MoO 3 film (83.1%) (Figure d). Furthermore, for more detailed information about the electronic structure of both metal oxides, the values of the conduction band minimum ( E c ), valence band maximum ( E v ), and Fermi energy level ( E Fermi ) were extracted from Tauc plots of the absorption spectra and ultraviolet photoelectron spectroscopy (UPS) analysis (Figures S2 and S3).…”

Section: Resultsmentioning

confidence: 99%

Photopically Transparent Organic Solar Cells with Tungsten Oxide-Based Multilayer Electrodes

Oh,

Kim,

Kim

et al. 2023

ACS Appl. Mater. Interfaces

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The tailoring of the average photopic transmittance (APT) of transparent organic solar cells (T-OSCs) has been the greatest challenge in building-integrated photovoltaic applications for future smart solar windows to regulate indoor brightness, maintain a human circadian rhythm, and positively impact human emotions by allowing the observation of the external environment. However, a notorious trade-off exists between the APT and power conversion efficiency (PCE) of T-OSCs, mainly due to the absence of highly conductive and transparent top electrodes, which are a key building block determining the PCE and APT. Herein, we demonstrate a new tungsten oxide (WO 3 )-based multilayer as a highly conductive and transparent top electrode that provides an excellent APT while maintaining a high PCE in T-OSCs. With the assistance of optical simulation based on a transfer matrix method to calculate the optimum thicknesses of the multilayer electrodes, we achieve the best-performing T-OSC with a PCE of 7.0% and a full device APT of 46.7%, resulting in a high light utilization efficiency of 3.27%, which is superior to that of T-OSCs based on the same photoactive system. Furthermore, superior thermal stability at 85 °C in an N 2 atmosphere is observed in WO 3based T-OSCs, maintaining 98% of the initial PCE after about 231 h. Our findings provide new insights into the development of T-OSCs with high efficiency and transparency.

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“…The huge increase of average particle size of the samples calcined above 600 °C results in less grain boundaries available for reflection and increased depth of penetration of incident light in to the tungsten oxide lattice [38]. The enhanced free electrons inside the lattice absorb this incident radiation in the NIR region at ∼900 nm and ∼ 1700 nm by polaron absorption and plasmon absorption respectively [37,39]. Thus, the NIR reflectance of tungsten oxide nanostructures calcined above 600 °C reduces thereafter.…”

Section: Nir Reflectance Studiesmentioning

confidence: 99%

Regulating NIR reflecting property of hydrothermally synthesized tungsten oxide nanostructures via calcination

Nair,

Keerthana,

James

et al. 2023

Phys. Scr.

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Present work primarily aims to study the near infrared (NIR) reflecting property of tungsten oxide nanostructures synthesized using hydrothermal method. As-synthesized hydrated tungsten oxide (WO3. H2O) sample was subjected to calcination at temperatures 300, 600, 700, 800 and 900 °C respectively for 1 hour and corresponding NIR reflecting performance of the obtained anhydrous tungsten oxide (WO3) nanostructures was analyzed using spectrophotometer. Thermal, structural, morphological, compositional and photoluminescence properties of the nanostructures were also characterized. Moreover, color variation of all samples was identified using CIE L*a*b* color analysis. The sample calcined at 600 °C showed a remarkable NIR reflectance of 91 % with color coordinates L* = 70.21, a* = - 4.28, b* = 22.47, h* = 100.78°, and C* = 22.87. Particle size and oxygen vacancies were found to play a significant role in NIR reflectance ability of tungsten oxide. The present work provides new insight into developing NIR reflecting tungsten oxide powders to be used as environmentally friendly cool materials for buildings and automobiles with energy saving performance.

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Effect of substrate temperature on the near-infrared shielding properties of WO3-x thin films deposited by RF magnetron sputtering

Cited by 14 publications

References 53 publications

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films

Photopically Transparent Organic Solar Cells with Tungsten Oxide-Based Multilayer Electrodes

Regulating NIR reflecting property of hydrothermally synthesized tungsten oxide nanostructures via calcination

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Effect of substrate temperature on the near-infrared shielding properties of WO3-x thin films deposited by RF magnetron sputtering

Cited by 14 publications

References 53 publications

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga2O3 thin films

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga2O3 thin films

Photopically Transparent Organic Solar Cells with Tungsten Oxide-Based Multilayer Electrodes

Regulating NIR reflecting property of hydrothermally synthesized tungsten oxide nanostructures via calcination

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Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga₂O₃ thin films