Amnuyswat, Kittiphong
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Preferred name
Amnuyswat, Kittiphong
Alternative Name
Amnuyswat, K.
Main Affiliation
Email
kittiphong.am@kmitl.ac.th
8 results
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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, 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, Hybrid Functional Calculation of Defects in Pseudo-binary Indium Oxynitride(2016-06-01); Indium oxynitride (InO<inf>x</inf>N<inf>y</inf>) is an attractive material that shows multi-functionality in electronic and optical applications due to its wide range tunable band gap. However there were only few studies available for this interesting material, especially on defect structure. In this work, first-principles calculation based on Density Functional Theory (DFT) within the Heys, Scuseria and Ernzerhof (HSE) hybrid functional for exchange-correlation energy was performed to investigate atomic structure, electronic properties and role of oxygen (O) defects occurred by means of their defect formation energies. The defect formation energies of both oxygen defects were compared with all possible native point defects in indium nitride. Our results revealed that O atom prefers to substitute in N site since it has lowest formation energy for all equilibrium crystal growth conditions. This result is consistent with the experimental observations by RF magnetron sputtering method. Moreover, the energy gap of indium nitride calculated by HSE method is 0.710 eV. The HSE calculation showed that the O antisite slightly widening the indium nitride band gap to 0.766 eV while the N vacancy gives wider indium nitride band gap of 1.410 eV. The complex defects of N vacancy and O antisite were also performed and 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); ; - 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.