Investigations of structural, optical, and photovoltaic properties of Fe-alloyed ZnS quantum dots

Crystal Research and Technology

Farag

Ahmed

2021

Nano MnS and ZnS samples are prepared through a simple thermolysis procedure. The effect of synthesis temperature on the different phases formed and their percentages, and on the lattice parameters and crystallite size of MnS and ZnS is examined using Rietveld analysis for X‐ray diffraction patterns. The minimum synthesis temperature at which MnS can be formed by the present simple procedure is 250 °C, while ZnS can be prepared at a lower temperature of 200 °C. For manganese sulfide, traces of Mn3O4 phase appear at 300 °C and increase with temperature, while ZnS resists oxidation until 500 °C; pure ZnO forms at 700 °C. The MnS and ZnS samples, obtained at all temperatures, are found to be biphasic; cubic and hexagonal. The nano nature of the samples and the particle morphology are investigated by high‐resolution transmission electron microscopy. Fourier‐transform infrared spectroscopy is applied to follow the characteristic vibration bands in both systems. The values of the different energy gaps depend on the crystallite size, phases’ percentages, and the preparation temperature. The photoluminescence intensity and the emitted colors from MnS and ZnS depend on the synthesis temperature.

Section: Resultsmentioning

confidence: 99%

Influence of Synthesis Temperature on the Phases Developed and Optical Properties of Manganese Sulfide and Zinc Sulfide

Crystal Research and Technology

Farag

Ahmed

2021

“…30 Similar characteristics were reported in Mn-doped ZnS formed by co-precipitation procedure 31 and annealed ZnS/Mn formed using hydrothermal method, 18 where the absorption decreased with Mn doping. However, Patel et al 32 and Horoz et al 33 revealed that the optical absorption of ZnS increased as it doped with 10% Co or Fe. For direct transition, the incident photon energy (hυ), the absorption coefficient (α), and energy bandgap (E g ) of the material are correlated through the Tauc's plot 34 ; where B, A, and t are constant, absorbance and thickness of the sample.…”

Section: Optical Propertiesmentioning

confidence: 99%

Effect of doping and changing of the annealing temperature on the structural and optical properties of ZnS

Int J Applied Ceramic Tech

2019

Nano ZnS doped with Co, Mn, or Fe have been synthesized via thermolysis technique at different annealing temperatures (300, 400, and 500°C). The effect of doping and annealing temperature on the lattice parameter and crystalline size of ZnS are studied in detail by Rietveld refinement method of X‐ray diffraction data. To confirm the formation of a zinc blend structure of annealed and doped ZnS, Fourier‐transform infrared are investigated. The energy gaps of doped and annealed ZnS are determined using ultraviolet spectroscopy technique. Undoped and doped ZnS with Fe emitted violet, blue, and green colors depend on the annealing temperature. Moreover, Mn‐doped ZnS exhibits blue‐green emission, while Co‐doped ZnS has a blue emission only.

“…Doping chalcogenide or oxide materials with different transition metals such as Cu, Mn, Ni, Cr, V, Co or Fe can change their properties [12][13][14][15][16]. The efficiency of the solar cells of Fe-doped ZnS QDs was improved as the amount of iron doping increased in ZnS lattice as compared with the undoped sample [17]. The improvement of the band gap and the high transmittance value revealed in Cd 0.94 Zn 0.04 Fe 0.02 S films nominated it to be used effectively in solar energy and photocatalytic activity under visible light [18].…”

Section: Introductionmentioning

confidence: 99%

Structure, optical and electronic characteristics of iron-doped cadmium sulfide under nonambient atmosphere

Badawi

2021

Appl. Phys. A

Iron-doped nano CdS was prepared in air and underflow of nitrogen applying the thermolysis technique. The impact of air and nitrogen atmosphere on the crystallinity and the different structure parameters of the obtained samples was investigated using X-ray diffraction measurements and applying Rietveld method. Analysis revealed the presence of two phases for CdS; hexagonal wurtzite and cubic zincblende with phase percentages greatly affected with preparation conditions; sample obtained under N 2 is almost pure hexagonal (97%). The particle morphology was investigated by FE-SEM, and the associated EDS spectra manifested elements percentages in accordance with those intended for preparation. The optical bandgap was greatly affected; compared with samples formed in air, it reduced upon doping with Fe as well as upon preparation under N 2 , it decreased from 2.58 eV for pristine CdS to 1.99 eV for Fe-doped CdS under N 2 . The photoluminescence (PL) intensity was also affected by the condition of preparation and iron doping. Pure and Fe-doped CdS samples emitted violet and blue colors. Density function theory (DFT) calculations were performed to explain the reason for the reduction of the optical bandgap upon doping CdS with Fe. The comparison between different electronic characteristics of pure and Fe-doped CdS samples was explored also by DFT calculation.