scholarly journals Effect of the Ammonium Tungsten Precursor Solution with the Modification of Glycerol on Wide Band Gap WO3 Thin Film and Its Electrochromic Properties

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Jinxiang Liu ◽  
Guanguang Zhang ◽  
Kaiyue Guo ◽  
Dong Guo ◽  
Muyang Shi ◽  
...  
Keyword(s):  
Band Gap ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Sol Gel ◽  
Wide Band ◽  
Sample Solution ◽  
Scanning Calorimetry ◽  
Wide Band Gap ◽  
Monoclinic Crystal ◽  
Ammonium Tungstate

Tungsten trioxide (WO3) is a wide band gap semiconductor material, which is commonly not only used, but also investigated as a significant electrochromic layer in electrochromic devices. WO3 films have been prepared by inorganic and sol-gel free ammonium tungstate ((NH4)2WO4), with the modification of glycerol using the spin coating technique. The surface tension, the contact angle and the dynamic viscosity of the precursor solutions demonstrated that the sample solution with a 25% volume fraction of glycerol was optimal, which was equipped to facilitate the growth of WO3 films. The thermal gravimetric and differential scanning calorimetry (TG-DSC) analysis represented that the optimal sample solution transformed into the WO3 range from 220 °C to 300 °C, and the transformation of the phase structure of WO3 was taken above 300 °C. Fourier transform infrared spectroscopy (FT-IR) spectra analysis indicated that the composition within the film was WO3 above the 300 °C annealing temperature, and the component content of WO3 was increased with the increase in the annealing temperature. The X-ray diffraction (XRD) pattern revealed that WO3 films were available for the formation of the cubic and monoclinic crystal structure at 400 °C, and were preferential for growing monoclinic WO3 when annealed at 500 °C. Atomic force microscope (AFM) images showed that WO3 films prepared using ammonium tungstate with modification of the glycerol possessed less rough surface roughness in comparison with the sol-gel-prepared films. An ultraviolet spectrophotometer (UV) demonstrated that the sample solution which had been annealed at 400 °C obtained a high electrochromic modulation ability roughly 40% at 700 nm wavelength, as well as the optical band gap (Eg) of the WO3 films ranged from 3.48 eV to 3.37 eV with the annealing temperature increasing.

scholarly journals Effects of Annealing Temperature on Optical Band Gap of Sol-gel Tungsten Trioxide Films

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 377 ◽  
Author(s):  
Guanguang Zhang ◽  
Kuankuan Lu ◽  
Xiaochen Zhang ◽  
Weijian Yuan ◽  
Muyang Shi ◽  
...  
Keyword(s):  
Band Gap ◽  
Tungsten Trioxide ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Wide Band ◽  
X Ray Diffraction ◽  
Electrochromic Devices ◽  
Wide Band Gap ◽  
Atomic Force

Tungsten trioxide (WO3) is a wide band gap semiconductor material that is used as an important electrochromic layer in electrochromic devices. In this work, the effects of the annealing temperature on the optical band gap of sol-gel WO3 films were investigated. X-ray Diffraction (XRD) showed that WO3 films were amorphous after being annealed at 100 °C, 200 °C and 300 °C, respectively, but became crystallized at 400 °C and 500 °C. An atomic force microscope (AFM) showed that the crystalline WO3 films were rougher than the amorphous WO3 films (annealed at 200 °C and 300 °C). An ultraviolet spectrophotometer showed that the optical band gap of the WO3 films decreased from 3.62 eV to 3.30 eV with the increase in the annealing temperature. When the Li+ was injected into WO3 film in the electrochromic reaction, the optical band gap of the WO3 films decreased. The correlation between the optical band gap and the electrical properties of the WO3 films was found in the electrochromic test by analyzing the change in the response time and the current density. The decrease in the optical band gap demonstrates that the conductivity increases with the corresponding increase in the annealing temperature.

scholarly journals Temperature-Controlled Crystal Size of Wide Band Gap Nickel Oxide and Its Application in Electrochromism

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 80
Author(s):  
Muyang Shi ◽  
Tian Qiu ◽  
Biao Tang ◽  
Guanguang Zhang ◽  
Rihui Yao ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Band Gap ◽  
Crystallite Size ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Wide Band ◽  
Degree Of Crystallinity ◽  
Wide Band Gap ◽  
Nio Films

Nickel oxide (NiO) is a wide band gap semiconductor material that is used as an electrochromic layer or an ion storage layer in electrochromic devices. In this work, the effect of annealing temperature on sol-gel NiO films was investigated. Fourier transform infrared spectroscopy (FTIR) showed that the formation of NiO via decomposition of the precursor nickel acetate occurred at about 300 °C. Meanwhile, an increase in roughness was observed by Atomic force microscope (AFM), and precipitation of a large number of crystallites was observed at 500 °C. X-ray Diffraction (XRD) showed that the NiO film obtained at such a temperature showed a degree of crystallinity. The film crystallinity and crystallite size also increased with increasing annealing temperature. An ultraviolet spectrophotometer was used to investigate the optical band gap of the colored NiO films, and it was found that the band gap increased from 3.65 eV to 3.74 eV with the increase in annealing temperature. An electrochromic test further showed that optical modulation density and coloring efficiency decreased with the increase in crystallite size. The electrochromic reaction of the nickel oxide film is more likely to occur at the crystal interface and is closely related to the change of the optical band gap. An NiO film with smaller crystallite size is more conducive to ion implantation and the films treated at 300 °C exhibit optimum electrochromic behavior.

The wide band gap of highly oriented nanocrystalline Al doped ZnO thin films from sol–gel dip coating

2009 ◽  
Vol 470 (1-2) ◽  
pp. 408-412 ◽  
Author(s):  
T. Ratana ◽  
P. Amornpitoksuk ◽  
T. Ratana ◽  
S. Suwanboon
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Sol Gel ◽  
Wide Band ◽  
Dip Coating ◽  
Zno Thin Films ◽  
Wide Band Gap ◽  
Doped Zno

scholarly journals PERFORMANCE EVALUATION OF ZNO DOPED DIDYMIUM NANO POWDER SAMPLES

2015 ◽  
pp. 202-205
Author(s):  
MANISH SHARMA ◽  
R.P. GAIROLA
Keyword(s):  
Band Gap ◽  
Sol Gel ◽  
Wide Band ◽  
Hexagonal Structure ◽  
Major Constituent ◽  
Homogeneous Distribution ◽  
Wide Band Gap ◽  
Light Emitting Devices ◽  
Powder Samples ◽  
P Type

In the recent years, much attention has been focused on wide band gap semiconductors materials because of their excellent potential for blue light emitting devices, short-wavelength laser diodes and detectors in UV-blue spectral region. The wide band gap ZnO is gaining much importance for the possible application due to the capability of ultraviolet lasing at room temperature and possibilities to engineer the band gap for further use. In order to attain the potential offered by ZnO, both high-quality n-and p-type ZnO are essential. In this work we synthese the ZnO nanopowder by Sol–gel method & after that the ZnO is doped with rare earth material didymium. Didymium is a naturally occurring element with major constituent Nd and Pr and is used in many applications. The FTIR, SEM and EDX characterization techniques are applied to study the sample & it has been found that the formation of pure phase of ZnO having wurtzite hexagonal structure occurs at 1%, But at higher concentration of Di (3%, 5%) the system shows mixed phase. Moreover SEM shows that the Di doped ZnO has well ordered morphology, has low aggregation and homogeneous distribution of particle size. Note that the synthesized system is also having band gap of 3.24 eV which is comparable with the standard value.

PREPARATION AND STRUCTURAL CHARACTERIZATION OF BINARY CATALYST FOR DYE WASTEWATER

2017 ◽  
Vol 79 (1-2) ◽  
Author(s):  
Zanariah Rajis ◽  
Mohammad Noorul Anam Mohd Norddin ◽  
Azeman Mustafa ◽  
Ahmad Fauzi Ismail
Keyword(s):  
Band Gap ◽  
Photocatalytic Oxidation ◽  
Sol Gel ◽  
Visible Region ◽  
Wide Band ◽  
Xrd Analysis ◽  
Synthetic Dyes ◽  
Dye Wastewater ◽  
Wide Band Gap ◽  
Binary Catalyst

Synthetic dyes used in most industries have persistence chemical compounds which cannot be degraded by conventional method. To overcome this problem, researchers utilize photocatalytic oxidation and TiO2 has become favourite photocatalyst. However, TiO2 has wide band gap and needs modification. One of the modifications is binary catalyst which found to be more effective as it commonly binds another photocatalyst that is readily exist in visible region to TiO2. Over the past 5 years Ag2O has been a chosen catalyst due to its low band gap. However, Ag2O often experiences self-aggregation. Thus, the optimum doping ratio of TiO2/Ag2O was determine by physical blend of TiO2 and Ag2O into 2 ratios, which were 1% Ag2O and 5% Ag2O. TiO2 was synthesized using sol gel method and Ag2O was synthesized using co-percipitation method. Both catalysts were blended physically and characterized using FESEM-EDX and XRD analysis. EDX mapping analysis showed TiO2/ Ag2O -5% exhibit better distribution of Ag2O. In addition, XRD analysis shows TiO2/ Ag2O -5% has more intense Ag2O peaks compare to TiO2/ Ag2O -1%. Based on the characterization results, TiO2/ Ag2O-5% showed promising ratio loading for dye wastewater photocatalytic degradation. 

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

Wide Band-Gap Kesterite Thin Films for Photovoltaic Applications

2018 ◽  
Author(s):  
Raquel Caballero ◽  
Leonor de la Cueva ◽  
Andrea Ruiz-Perona ◽  
Yudenia Sánchez ◽  
Markus Neuschitzer ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Wide Band ◽  
Wide Band Gap ◽  
Photovoltaic Applications
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