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.

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 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.

INFLUENCE OF ANNEALING TEMPERATURE ON THE CHARACTERISTICS OF NANOCRYSTALLINE SnO2 THIN FILMS PRODUCED BY Sol–Gel AND CHEMICAL BATH DEPOSITION FOR GAS SENSOR APPLICATIONS

2017 ◽  
Vol 24 (07) ◽  
pp. 1750104 ◽  
Author(s):  
SELMA M. H. AL-JAWAD ◽  
ABDULHUSSAIN K. ELTTAYF ◽  
AMEL S. SABER
Keyword(s):  
Band Gap ◽  
Gas Sensor ◽  
Chemical Bath Deposition ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Dip Coating ◽  
Rutile Structure ◽  
Sensor Applications ◽  
Average Grain Size

Pure nanocrystalline SnO2 films were grown on a clean glass substrate by using sol–gel dip coating and chemical bath deposition (CBD) techniques for gas sensor applications. The films were annealed in air at 300[Formula: see text]C, 400[Formula: see text]C, and 500[Formula: see text]C for 60[Formula: see text]min. The deposited films with a thickness of approximately 300 [Formula: see text] 20 nm were analyzed through X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical absorption spectroscopy. Results revealed that the films produced by dip coating exhibited a tetragonal rutile structure and those produced by CBD showed a tetragonal rutile and orthorhombic structure. The crystalline sizes of the films produced by dip coating annealed at 300[Formula: see text]C, 400[Formula: see text]C, and 500[Formula: see text]C were 8, 14, and 22.34 nm and those for CBD films at these temperatures were 10, 15, and 22 nm, respectively. AFM and SEM results indicated that the average grain size increased as annealing temperature increased. The transmittance and absorbance spectra were then recorded at wavelengths ranging from 300[Formula: see text]nm to 1000[Formula: see text]nm. The films produced by both the methods yielded high transmission at visible regions. The optical band gap energy of dip-coated films also increased as annealing temperature increased. In particular, their optical band gap energies were 3.5, 3.75, and 3.87[Formula: see text]eV at 300[Formula: see text]C, 400[Formula: see text]C, and 500[Formula: see text]C, respectively. By comparison, the energy band gap of CBD-prepared films decreased as annealing temperature increased, and their corresponding band gaps were 3.95, 3.85, and 3.8[Formula: see text]eV at the specified annealing temperatures. The films were further investigated in terms of their sensing abilities for carbon monoxide (CO) gas at 50 ppm by measuring their sensitivity to this gas at different times and temperatures. Our results demonstrated that dip-coated and CBD-prepared films were highly sensitive to CO at 200[Formula: see text]C and 250[Formula: see text]C, respectively.

scholarly journals Semiconducting properties of Ge-doped BaSnO3 ceramic

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Wide Band ◽  
Rate Of Change ◽  
Wide Band Gap ◽  
Electrical And Optical Properties ◽  
Optical Band Gaps ◽  
Semiconducting Properties ◽  
Semiconductor Behavior ◽  
Maximum Conductivity

The electrical and optical properties of Ge-doped BaSnO3 ceramics sintered at varioustemperatures have been investigated to determine their semiconductor behavior. The electricalconductivity of Ge-doped BaSnO3 samples increases with increase in temperature, confirmingthat the samples exhibit a semiconductor behavior. A maximum conductivity value of6.31 × 10−9 S/cm was observed for the sample sintered at 1200 °C. The optical band gaps ofthe Ge-doped BaSnO3 samples were determined by means of reflectance spectra. The variation of optical band gap with temperature was analyzed using Eg(T) = Ego + βT relation. The rate of change of the band gap β of BaSn0.99Ge0.01O3 was found to be 7.6 × 10−4 (eV/°C).A minimum optical band gap value of 2.95 eV was observed for the sample sintered at 1400 °C. It is evaluated that BaSn0.99Ge0.01O3 is a wide band gap semiconductor and its semiconducting properties change with sintering temperature.

scholarly journals High-efficiency photovoltaic cells with wide optical band gap polymers based on fluorinated phenylene-alkoxybenzothiadiazole

2017 ◽  
Vol 10 (6) ◽  
pp. 1443-1455 ◽  
Author(s):  
Seo-Jin Ko ◽  
Quoc Viet Hoang ◽  
Chang Eun Song ◽  
Mohammad Afsar Uddin ◽  
Eunhee Lim ◽  
...  
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
High Performance ◽  
Optical Band Gap ◽  
High Efficiency ◽  
Bulk Heterojunction ◽  
Polymer Solar Cells ◽  
Photovoltaic Cells ◽  
Wide Band ◽  
Wide Band Gap

A new series of wide band gap photovoltaic polymers based on a fluorinated phenylene-alkoxybenzothiadiazole unit with an optical band gap of over 1.90 eV are designed and utilized for high-performance single- and multi-junction bulk heterojunction polymer solar cells.

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.

Sign in / Sign up

Export Citation Format

Share Document