Ab-initio calculation of the physical properties of some beryllium based semiconductors / Mohamed Abdelilah Fadla

Public ISBD Titre : Ab-initio calculation of the physical properties of some beryllium based semiconductors Type de document : texte manuscrit Auteurs : Mohamed Abdelilah Fadla, Auteur ; Bachir Bentria, Directeur de thèse Editeur : Laghouat : Université Amar Telidji - Département des sciences de la matière Année de publication : 2018 Importance : 44 p. Format : 30 cm. Accompagnement : 1 disque optique numérique (CD-ROM) Note générale : Option : Material physics Langues : Anglais (eng) Mots-clés : Beryllium  Semiconductors Résumé : The aim of this dissertation is the ab initio calculation of the properties: structural, electronic, elastic and optic of a Beryllium based ternary compounds, The calculation is conducted in the frame work of the density functional theory (DFT) used pseudo potential plane wave method (PPPW) which is implanted in the CASTEP and ABINIT codes The different physical properties calculated using the generalized gradient approximation of Perdew-Burke Ernzerhof (GGA-PBE), for calculate the band gap I used the hybrid functional HSE06 it gives a result with a high degree of reliability. All compound are a hard semiconductor with high melting temperature, BeCN2 and BeSiN2 have a large transparency domain all compounds have a good birefringence all this characteristics could make these materials useful as nonlinear crystals for many applications. note de thèses : Mémoire de master en physique Ab-initio calculation of the physical properties of some beryllium based semiconductors [texte manuscrit] / Mohamed Abdelilah Fadla, Auteur ; Bachir Bentria, Directeur de thèse . - Laghouat : Université Amar Telidji - Département des sciences de la matière, 2018 . - 44 p. ; 30 cm. + 1 disque optique numérique (CD-ROM). Option : Material physics Langues : Anglais (eng) Mots-clés : Beryllium  Semiconductors Résumé : The aim of this dissertation is the ab initio calculation of the properties: structural, electronic, elastic and optic of a Beryllium based ternary compounds, The calculation is conducted in the frame work of the density functional theory (DFT) used pseudo potential plane wave method (PPPW) which is implanted in the CASTEP and ABINIT codes The different physical properties calculated using the generalized gradient approximation of Perdew-Burke Ernzerhof (GGA-PBE), for calculate the band gap I used the hybrid functional HSE06 it gives a result with a high degree of reliability. All compound are a hard semiconductor with high melting temperature, BeCN2 and BeSiN2 have a large transparency domain all compounds have a good birefringence all this characteristics could make these materials useful as nonlinear crystals for many applications. note de thèses : Mémoire de master en physique

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Theoretical calculation of physical properties for some new potential perovskites for solar energy conversion / Mohamed Abdelilah Fadla

Public ISBD Titre : Theoretical calculation of physical properties for some new potential perovskites for solar energy conversion Type de document : texte manuscrit Auteurs : Mohamed Abdelilah Fadla, Auteur ; Bachir Bentria, Directeur de thèse Editeur : Laghouat : Université Amar Telidji - Département des sciences de la matière Année de publication : 2022 Importance : 92 p Format : 27 cm Accompagnement : 1 disque optique numérique (CD-ROM) Note générale : Option : Material physics Langues : Anglais (eng) Catégories : THESES :17 physique Résumé : Organometallic perovskite solar cells have attracted great attention in the last years. They exhibit very low production cost, due to their simple preparation method, coupled to high power conversion effciencies (up to 26% for Formamidinium Lead iodide perovskite FAPbI3). This is achieved after just few years following their discovery. However, organometallic perovskite are very sensitive to moisture, oxygen and light due to the presence of organic cations. The smaller cesium cation has been used to replace organic cations to resolve the instability issues of organometallic perovskite. In this thesis, frst principle computation method is used to understand perovskite’s high power conversion effciency. The structural stability, electronic and optical properties of CsPbI3 polymorphs are investigated as well as some carrier transport properties. The lower symmetry orthorhombic Pnam black phase is more energetically favourable compared to tetragonal phase and the high symmetric cubic phase. Lead as well as iodide atoms play signifcant role in the high optical absorption (more 105Cm−1). Mixed halide perovskite CsPb(I1−xBrx)3 at low symmetry black phase (Pnam) are investigated to increase material stability and adjust the optoelectronic properties. The iodine bromine partial substitution signifcantly enhances material stability. The carrier mobility are computed through deformation potential theory, and both CsPbI3 and CsPbBr3 compounds show very low effective mass. Band alignment approach is used to fnd suitable electron and hole transport materials. By means of super cell approach as well as FNV-KO scheme, the defect tolerance of cesium lead halide perovskite is discussed by studying all possible intrinsic point defects. Several defects create shallow levels, while the iiiintrinsic defects that may create deep levels have high formation energies especially under Iodine and Bromine poor conditions. note de thèses : Thèse de doctorat en physique Theoretical calculation of physical properties for some new potential perovskites for solar energy conversion [texte manuscrit] / Mohamed Abdelilah Fadla, Auteur ; Bachir Bentria, Directeur de thèse . - Laghouat : Université Amar Telidji - Département des sciences de la matière, 2022 . - 92 p ; 27 cm + 1 disque optique numérique (CD-ROM). Option : Material physics Langues : Anglais (eng) Catégories : THESES :17 physique Résumé : Organometallic perovskite solar cells have attracted great attention in the last years. They exhibit very low production cost, due to their simple preparation method, coupled to high power conversion effciencies (up to 26% for Formamidinium Lead iodide perovskite FAPbI3). This is achieved after just few years following their discovery. However, organometallic perovskite are very sensitive to moisture, oxygen and light due to the presence of organic cations. The smaller cesium cation has been used to replace organic cations to resolve the instability issues of organometallic perovskite. In this thesis, frst principle computation method is used to understand perovskite’s high power conversion effciency. The structural stability, electronic and optical properties of CsPbI3 polymorphs are investigated as well as some carrier transport properties. The lower symmetry orthorhombic Pnam black phase is more energetically favourable compared to tetragonal phase and the high symmetric cubic phase. Lead as well as iodide atoms play signifcant role in the high optical absorption (more 105Cm−1). Mixed halide perovskite CsPb(I1−xBrx)3 at low symmetry black phase (Pnam) are investigated to increase material stability and adjust the optoelectronic properties. The iodine bromine partial substitution signifcantly enhances material stability. The carrier mobility are computed through deformation potential theory, and both CsPbI3 and CsPbBr3 compounds show very low effective mass. Band alignment approach is used to fnd suitable electron and hole transport materials. By means of super cell approach as well as FNV-KO scheme, the defect tolerance of cesium lead halide perovskite is discussed by studying all possible intrinsic point defects. Several defects create shallow levels, while the iiiintrinsic defects that may create deep levels have high formation energies especially under Iodine and Bromine poor conditions. note de thèses : Thèse de doctorat en physique

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Theoretical study of emerging perovskite materials for solar energy conversion / Sabrina Djeradi

Public ISBD Titre : Theoretical study of emerging perovskite materials for solar energy conversion Type de document : document multimédia Auteurs : Sabrina Djeradi, Auteur ; Taher Daham, Directeur de thèse ; Mohamed Abdelilah Fadla, Directeur de thèse Editeur : Laghouat : Université Amar Telidji - Département des sciences de la matière Année de publication : 2025 Importance : 102 p. Accompagnement : 1 disque optique numérique (CD-ROM) Note générale : Option : Materials physics Langues : Anglais (eng) Mots-clés : Double perovskites  Mixed-halide alloys  CsPb(I1−xBrx)3  Machine learn- ing  Ensemble learning  Density functional theory (DFT)  Special quasirandom structure (SQS)  Optoelectronic properties  Tandem solar cells Résumé : The efficiency of perovskite solar cells (PSCs) has increased quickly, reaching 26.7% for single-junction devices and over 34% when combined with silicon . PSCs have excel- lent prospects for next-generation photovoltaics due to their great optical absorption, high carrier mobility, and adjustable direct band gaps. Commercialization is still severely ham- pered by insufficient stability under environmental stress, where long-term stability is cru- cial. The stability problem is addressed in this thesis by combining two approaches into a single materials design process. First, the band gap of double perovskites is predicted us- ing composition-based characteristics alone employing a high-through ensemble machine learning algorithms. As a result, stable and effective candidates may be quickly screened without incurring the computational expense of comprehensive quantum computations. Second, spin-orbit coupling (SOC) and hybrid HSE06 functionals are used in the density functional theory calculations (DFT) for a specific type of mixed-halideCsPb(I1–xBrx)3 alloys. In order to capture atomic disorder and allow for a thorough examination of struc- tural, electronic, and optical characteristics, these systems are represented using the spe- cial quasirandom structure (SQS) technique.The workflow connects the two approaches in which DFT refines and tests the stability and optoelectronic behavior of potential com- positions identified by machine learning at the atomic level. The results indicate that, with only a little decrease in apparent absorption, bromide inclusion improves structural stabil- ity, linearly adjusts the band gap, and modifies band offsets based on surface termination. This study shows a productive, data-driven approach to finding and improving stable, high-performance perovskites by combining predictive modeling with focused first-principles simulations. The strategy may be used to balance environmental resilience and efficiency when customizing materials for silicon-based tandem solar cells. note de thèses : Thèse de doctorat en physique Theoretical study of emerging perovskite materials for solar energy conversion [document multimédia] / Sabrina Djeradi, Auteur ; Taher Daham, Directeur de thèse ; Mohamed Abdelilah Fadla, Directeur de thèse . - Laghouat : Université Amar Telidji - Département des sciences de la matière, 2025 . - 102 p. + 1 disque optique numérique (CD-ROM). Option : Materials physics Langues : Anglais (eng) Mots-clés : Double perovskites  Mixed-halide alloys  CsPb(I1−xBrx)3  Machine learn- ing  Ensemble learning  Density functional theory (DFT)  Special quasirandom structure (SQS)  Optoelectronic properties  Tandem solar cells Résumé : The efficiency of perovskite solar cells (PSCs) has increased quickly, reaching 26.7% for single-junction devices and over 34% when combined with silicon . PSCs have excel- lent prospects for next-generation photovoltaics due to their great optical absorption, high carrier mobility, and adjustable direct band gaps. Commercialization is still severely ham- pered by insufficient stability under environmental stress, where long-term stability is cru- cial. The stability problem is addressed in this thesis by combining two approaches into a single materials design process. First, the band gap of double perovskites is predicted us- ing composition-based characteristics alone employing a high-through ensemble machine learning algorithms. As a result, stable and effective candidates may be quickly screened without incurring the computational expense of comprehensive quantum computations. Second, spin-orbit coupling (SOC) and hybrid HSE06 functionals are used in the density functional theory calculations (DFT) for a specific type of mixed-halideCsPb(I1–xBrx)3 alloys. In order to capture atomic disorder and allow for a thorough examination of struc- tural, electronic, and optical characteristics, these systems are represented using the spe- cial quasirandom structure (SQS) technique.The workflow connects the two approaches in which DFT refines and tests the stability and optoelectronic behavior of potential com- positions identified by machine learning at the atomic level. The results indicate that, with only a little decrease in apparent absorption, bromide inclusion improves structural stabil- ity, linearly adjusts the band gap, and modifies band offsets based on surface termination. This study shows a productive, data-driven approach to finding and improving stable, high-performance perovskites by combining predictive modeling with focused first-principles simulations. The strategy may be used to balance environmental resilience and efficiency when customizing materials for silicon-based tandem solar cells. note de thèses : Thèse de doctorat en physique

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