Thanomngam, Pitiporn
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Preferred name
Thanomngam, Pitiporn
Alternative Name
Thanomngam, P.
Thanomngam, Pittiporn
Main Affiliation
Email
pitiporn.th@kmitl.ac.th
23 results
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Item type:Publication, First-principles study of antisite defects in orthorhombic PbZrO 3(2014-09-02); T-Thienprasert, JirarojFirst-principles calculations based on density functional theory (DFT) within local density approximation were employed to investigate the antisite defects, including Pb<inf>Zr</inf> and Zr<inf>Pb</inf>, in orthorhombic PbZrO<inf>3</inf> by determining their defect formation energies. The formation energies of antisite defects were then compared with those of other dominant defects, i.e., lead Pb, zirconium Zr, and oxygen O vacancies to examine the likelihood of their existence. Our results revealed that Pb<inf>Zr</inf> defect in neutral charge state is the most dominant defect under O-rich or oxidizing condition in agreement with the previous work. In addition, there is a little structural relaxation when the Zr atom is replaced by Pb atom to form Pb <inf>Zr</inf> defect in neutral charge state. In opposite, under O-poor or reducing condition, the formation energies of antisite defects are quite high and higher than those of vacancy defects. This suggests that antisite defects are unlikely to form under reducing condition. © 2014 Taylor & Francis Group, LLC. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Roles of spin-orbit coupling in tetragonal hybrid halide perovskite for photovoltaics light-absorber(2018-01-01); Hybrid halide perovskite has been gain appropriate attraction because of their relatively high efficiency in most recently solid-state solar cell development. In this work, A first-principle calculation based on non-local van der Waals-corrected Density Functional Theory (vdW-DFT) is performed to investigate high accuracy atomic structures of a tetragonal structure methyl ammonium (CH<inf>3</inf>NH<inf>3</inf>) metal (Pb, Sn) halide (Br<inf>3</inf>, Cl<inf>3</inf>, I<inf>3</inf>). The calculated electronic structures were systematically studied using semi-local exchange-correlation functional (GGA-PBE), non-local functional (hybrid HSE06) and post-DFT approximation (GW). A relativistic effect in metal ion was taken into account by incorporating spin-orbit coupling (SOC) effect to obtain more accurate band gap properties of these materials. Our results shown that SOC corrected the electronic structures about 0.92 eV and 0.19 eV in case of lead ion and tin ion, respectively. The combination between GW approximation and spin-orbit coupling show a good agreement between DFT calculations and experimental studies. This computational scheme is necessary for high accuracy organic-inorganic solar cell design. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of pressure on structural and elastic properties of SnSe: First-principles calculations(2022-02-01); ; Limpijumnong, SukitSelected structural and elastic properties of an orthorhombic SnSe at an ambient pressure and under high pressures were investigated using first-principles calculations. At ambient pressure, the calculated structural parameters and elastic constants show a good agreement with previously reported values. Effects of pressure on structural and elastic properties were presented and discussed in detail. Moreover, the pressure dependence of selected structural and elastic properties, which relate to phase transition from an orthorhombic phase to the high-pressure phase, was analyzed. We suggested that the phase transition is related to the compression along the c- and b-axis which correspond to C<inf>33</inf> and C<inf>22,</inf> respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Structural and electronic properties of β-CuPc: First principles study(2016-01-01); Structural and electronic properties of CuPc in β structure (β-CuPc) were investigated by first principles calculations. The generalized gradient approximation (GGA) was used to describe the exchange-correlation with the projector-augmented wave (PAW) method. Under ambient pressure, the calculated structural parameters were calculated and found to be in good agreement with other experimental and theoretical values. The calculated direct band gap was found to be 0.683 eV. The results of electronic properties under various pressures were presented. To investigate the properties under pressure, β-CuPc was calculated at several reduced volumes. It was found that the energy gap decreases when the pressure increases. The behaviors of electronic properties under pressure were also discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of SnCl4 concentration on transparent and conducting undoped tin oxide thin films(2016-01-01); ; Thowladda, WarawootThe purpose-built pyrolysis system based on an ultrasonically generated aerosol has been successfully used for deposition of highly transparent and conductive undoped tin (IV) oxide thin films. The morphological, structural, optical and electrical properties as well as electronic structures of the films for different concentrations of SnCl<inf>4.</inf>5H<inf>2</inf>O used as the starting precursor were investigated. FE-SEM displayed the substrate surfaces were uniformly covered with the film. The film thickness varied with the precursor concentration. XRD patterns showed the deposited films were a tetragonal phase and presented random orientations. The optical transmission spectra of all films revealed highly transmittance in the visible region. Refractive index of the films was between 1.85 and 2.0. XPS spectra for the Sn 3d<inf>5/2</inf> and Sn 3d<inf>3/2</inf> confirmed that the films were composed of SnO and SnO2 phases. The non-stoichiometric composition decreased with increasing concentration of the precursor. The films deposited with 0.30 M showed the highest conductivity and carrier concentration of 17 ω<sup>-1</sup>cm<sup>-1</sup> and 9.5 x 10<sup>19</sup> cm<sup>-3</sup>, respectively. The disagreement of relation between XPS and Hall measurement suggested the higher carrier concentration arose from incorporation of residual chlorine from the solution precursor during deposition into the films. The interstitially incorporated chlorine considerably influenced the electrical properties of the films. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Investigation of oxygen contamination in indium nitride thin film by x-ray absorption fine structure(2010-02-05); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of exchange-correlation and GW approximations on electrical property of cubic, tetragonal and orthorhombic CH3NH3PbI3(2017-01-02); A first-principle calculations based on van der Waals-corrected Density Functional Theory (vdW-DFT) is performed to investigate atomic structure of methyl ammonium lead iodine (CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf>) which is a key material for high efficiency solid-state solar cell. A temperature dependent symmetry was previously reported which also included in this study. DFT calculation of electronic and optical properties are systematically studied with semi-local, non-local exchange-correlation and post-DFT approximation including PBE, HSE06 hybrid functional and GW. Relativistic effect in lead ion was taken into account by incorporating spin-orbit coupling (SOC) effect to obtain more accurate band gap of this material. With GW-SOC functional, our results of band gap calculations showed good agreement between DFT calculations and experimental studies which confirmed that this computational scheme is suitable for high accuracy material design, e.g. for solar cell applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, XAFS analysis of indium oxynitride thin films grown on silicon substrates(2013-01-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Improvement of energy gap prediction for hybrid perovskite materials by first-principle calculation(2018-09-05); The breakthrough discovery of pollution free renewable energy has been awarded to conversion of solar energy into electrical energy using planar heterojunction solar cell. A layer of hybrid perovskite light harvesting materials between transport layer and electrode is essential for high power conversion efficiency (PCE). In this work, first-principle calculation based on non-local van der Waals-corrected Density Functional Theory (vdW-DFT) is used to examine atomic structures of the most popular hybrid perovskite materials used in solar cell absorption layer. The optical band gaps achieved from electronic band structures were consistently studied using semi-local exchange-correlation functional (GGA-PBE) and post-DFT approximation (GW approximation). In order to improve band gap accuracy, we tried to compensate relativistic effect in metal ion using spin-orbit coupling (SOC). Our results showed that the energy gap predictions using first-principles GW calculations incorporate with SOC scheme are in good agreement with available experimental reports. Therefore, this calculation scheme is suggested for high accuracy organic-inorganic solar cell design. - Some of the metrics are blocked by yourconsent settings
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