Thanomngam, Pitiporn
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Thanomngam, Pitiporn
Alternative Name
Thanomngam, P.
Thanomngam, Pittiporn
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Email
pitiporn.th@kmitl.ac.th
14 results
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Item type:Publication, Investigation of structural properties of CuPc/TiO2 nanocomposites(2010-02-05); Structural properties of hybrid nanocomposites based on TiO<inf>2</inf> nanostructures and Copper phthalocyanine (CuPc) were investigated. The composites were prepared by mixing TiO<inf>2</inf> nanoparticle (TNP) and nanotube (TNT) with CuPc suspension. The precipitated composites were obtained by centrifuged and dried processes. Structural properties of the composites were evaluated by mean of Raman Spectroscopy and X-ray Absorption Fine Structure (XAFS). The results implied that CuPc has interatomic distance of C atoms in the second shell are decreased when CuPc is in the hybrid composites. © (2010) Trans Tech Publications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles investigation on elastic constants of TiN under high pressure(2013-10-29); Sarasamak, KanoknanElastic constants of NaCl-type TiN under pressure were investigated by first-principles calculations within both local density approximation (LDA) and Perdew-Burke-Ernzerhof generalized-gradient approximation (PBE-GGA). At ambient pressure, the calculated lattice parameter, bulk modulus, and elastic constants of NaCl-type TiN are in well agreement with other available values. Under pressure, all elastic constants, C<inf>11</inf>, C<inf>12</inf>, and C<inf>44</inf>, are found to increase with pressure. C<inf>11</inf>, which is related to the longitudinal distortion, increases rapidly with pressure while C<inf>12</inf> and C<inf>44</inf> which are related to the transverse and shear distortion, respectively, are much less sensitive to pressure. © (2013) Trans Tech Publications, Switzerland. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Band gap prediction of the alloying halide perovskites using GW compare to DFT-1/2 method(2020-10-26); The outstanding optoelectronic properties of methylammonium halide perovskites, including the tunable spectral absorption range, high carrier mobilities and low carrier recombination rates, make these materials are interesting for a decade year. In my works, 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 and their properties of the alloying halide perovskites (CH3NH3PbIxBr1-x). While DFT generally underestimates the band gap for practically semiconductors and insulators, it provided a surprising accurate value for methylammonium halide perovskites. Unfortunately, this performance is not existing to another hybrid halide perovskite. The relativistic GW approximation is known to be a better-provided band gap more accurately, but at an extremely high computational cost were applied to the study. Here we also report the efficiency and accuracy of the bandgap calculations of methylammonium halide perovskites by using the self-consistent quasiparticle GW method (scGW) incorporated with the spin-orbit coupling comparing to recent develops DFT-1/2 method. The latter computational scheme provides accurate band gaps with the precision of the scGW method with no more computational cost than standard DFT. This method can solve the band gap problem by correcting the half-hole/half-electron occupation in the pseudopotentials. This work yields the possibility of the band gap prediction of alloying halide perovskite material (CH3NH3PbIxBr1-x) that good for optoelectronic design such as planar dye solar cell. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Study on optical and electronic properties of Sn-doped ZnPc(2013-10-29); ; Sn doped ZnPc films were deposited on intrinsic Si and glass substrates by organic source thermal co-evaporation technique with different deposition rates. Optical properties and electronic structure were characterized by UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) respectively. The UV-Vis results showed that phase transition of ZnPc from α- phase to β-phase occurred when Sn:ZnPc deposition rate is 0.3:0.7 or higher. XPS results indicated that the outer s electron of Sn atom is transferred to the ZnPc. Broadening of the C 1s spectra is observed with the increasing of Sn deposition rate. This broadening corresponds to the change of molecular environment surrounding carbon atoms in the Sn-doped ZnPc films. © (2013) Trans Tech Publications, Switzerland. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First principles study on structural and electronic properties of Li, Na and K - Intercalated zinc phthalocyanine(2018-01-01); Recently, alkali metals doped zinc phthalocyanine (ZnPc) was found to be an effective method for tuning electronic properties of ZnPc. In this research, the effect of alkali metal atoms (Li, Na, and K) intercalation on structural and electronic properties of ZnPc in β structure was investigated by first principles calculations based on density function theory (DFT). The generalized gradient approximation (GGA) is used to describe the exchange-correlation with the projector-augmented wave (PAW) method. The calculated lattice constants, bond lengths and bond angles of pristine ZnPc are in good agreement with other calculations and experimental data. The calculated band gap energy of pristine ZnPc is found to be 1.327 eV. The lattice constants, molecular arrangement, bond lengths and bond angles are sensitive to intercalating alkali metal atoms. It was found that intercalating alkali metal atoms induce significant changes in the band gap energy of ZnPc. The changes in band gap energy with intercalating alkali metal atoms are discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Surface morphology and structural investigation of TiN nanocrystal thin films grown with different N2 concentration(2013-02-19); - 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, Monte-Carlo simulation of Bremsstrahlung interference due to K-shell photoelectrons in Compton scattering experiments(2004-10-01); Johnston, P. N.As a part of a larger study of Compton scattering from the K-shell electrons of Ta and Pb, Monte-Carlo simulation has been used to study X-rays emitted from 0.05mm thick Pb and Ta foils due to K-shell photoelectric absorption of 320 and 662keV incident γ-rays. The interference in such studies due to Bremsstrahlung from photoelectrons in coincidence with the K X-ray photons mimics the characteristics of the Compton scattering of interest and cannot be eliminated experimentally. In this work, the detector was calibrated at eight energies by experimental determination of the full energy peak and a Monte-Carlo modelling of the physical processes, which determine the detector efficiency and response function was undertaken. This physical model was then used to calculate the Bremsstrahlung emitted from 0.05mm thick Pb and Ta target foils due to K-shell photoelectrons originating from photoelectric absorption of 320 and 662keV incident γ-rays on the target. © 2004 Elsevier Ltd. All rights reserved. - 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, Local structure investigation of indium oxynitride thin films by X-ray absorption fine structure(2010-05-05); ;