Ces dernières décennies, l'urgence croissante de la crise énergétique et la prise de conscience qu'une grande partie de l'énergie utilisée dans le monde est dissipée sous forme de chaleur ont provoqué un engouement pour le développement de modules thermoélectriques performants. Ces dispositifs pourraient récupérer la chaleur provenant de procédés industriels ou d'autres sources, transformant un gradient de température en voltage grâce à l'effet Seebeck. Les matériaux thermoélectriques performants doivent posséder une faible conductivité thermique, une haute conductivité électrique et un grand coefficient Seebeck. L'optimisation simultanée de ces paramètres est un défi majeur pour la physique de la matière condensée et la science des matériaux. Dans l'optique d'améliorer les propriétés thermoélectriques de plusieurs matériaux prometteurs, nous explorons plusieurs stratégies dans lesquelles les défauts (substitutions atomiques, lacunes…), le désordre et le confinement dimensionnel jouent un rôle central. Nous réalisons des calculs en théorie de la fonctionnelle densité et des projections sur des orbitales de Wannier afin de construire des Hamiltoniens et des matrices dynamiques réalistes décrivant leur structure électronique et vibrationnelle dans l'espace réel. Ces paramètres sont ensuite utilisés pour calculer les propriétés de transport thermoélectrique en utilisant le formalisme de Kubo, l'équation de Boltzmann, le formalisme de Landauer et la méthode Chebyshev polynomial Green's function, qui permet un traitement exact du désordre. Nous étudions les propriétés de transport électronique et les performances thermoélectriques de deux matériaux prometteurs pour la production d'énergie à hautes températures, le titanate de strontium et l'oxyde de titane rutile. Nous obtenons un très bon accord entre nos prédictions et un grand nombre de données expérimentales. Nous montrons que l'augmentation du coefficient Seebeck observée dans les superlayers de titanate de strontium, jusque-là attribuée à des effets de confinement quantique, est en réalité très bien expliquée par l'hypothèse d'électrons délocalisés. Nous explorons les effets généraux des états résonant sur le transport électronique dans le cadre d'une étude modèle, et nous trouvons une augmentation d'un facteur six des performances thermoélectriques. Nous examinons ensuite le cas particulier du titanate de strontium, et nous montrons que les performances sont détruites par des effets de localisation si des atomes de Vanadium sont introduits comme impuretés résonantes. Nous étudions l'influence des défauts dans les matériaux bidimensionnels. Contrairement aux adatomes, nous montrons que les substitutions dans les dichalcogénures de métaux de transition ont pour effet de localiser les porteurs de charge. Nous étudions l'effet des lacunes sur le transport de phonons dans le graphène, et nous déterminons les taux de diffusion phonon-lacune. Nous obtenons un très bon accord entre notre théorie et des mesures de conductivité thermique dans des échantillons de graphène irradiés et de tailles finies / Over the past decades, the increasingly pressing need for clean energy sources and the realization that a huge proportion of the world energy consumption is wasted in heat have prompted great interest in developing efficient thermoelectric generation modules. These devices could harvest waste heat from industrial processes or other sources, turning a temperature gradient into a voltage through the Seebeck effect. Efficient thermoelectric materials should exhibit a low thermal conductivity, a high electrical conductivity and a high Seebeck coefficient. Simultaneously optimizing these parameters is a great challenge of condensed matter physics and materials science. With a view to enhance the thermoelectric properties of several promising materials, we explore several strategies in which defects (atomic substitutions, vacancies…), disorder and dimensional confinement play a crucial role. We perform density functional theory calculations and projections on Wannier orbitals to construct realistic Hamiltonians and dynamical matrices describing their electronic and vibrational structure in real space. These parameters are then used to compute the thermoelectric transport properties using the Kubo formalism, the Boltzmann transport equation, the Landauer formalism, and the Chebyshev polynomial Green's function method that allows for an exact treatment of disorder. We investigate the electronic transport properties and thermoelectric performances of two promising materials for high-temperature power generation, strontium titanate and rutile titanium dioxide. Comparison of our predictions with a wealth of experimental data yields a very good agreement. We show that the increase of the Seebeck coefficient observed in strontium titanate superlayers, until now attributed to quantum confinement effects, is in fact well explained assuming delocalized electrons. The general effects of resonant states on electronic transport are explored in a model study, showing a sixfold increase of the thermoelectric performances. The particular case of strontium titanate is then examined, and localization effects are shown to destroy the performances if Vanadium atoms are introduced as resonant impurities. The influence of defects in two-dimensional materials is investigated. Contrary to adatoms, substitutions in transition metal dichalcogenides are shown to localize the charge carriers. We study the effect of vacancies on phonon transport in graphene, and determine the phonon-vacancy scattering rate. Comparison with thermal conductivity data for irradiated and finite-size graphene samples yields a very good agreement between theory and experiments

Thermal conductivity and thermopower measurements in strongly correlated electron systems at low temperatures

Primarily, newly developed, high sensitive and accurate methods for thermal characterization of liquids using photothermal radiometry are presented. Two experimental configurations are suggested, tested and validated with usual liquid materials. These methods are used to study polymer dispersed liquid crystal samples. Dynamic thermal properties of samples are analysed verses amplitude varying applied electric field with constant frequency as well as versus frequency varying electric field with constant amplitude. Our results clearly show the thermal properties of the samples are prone to depolarizing field effects at the lower frequencies of the applied electric field. The experimental results are modeled against existing theories to predict electric properties of the sample composites. Second part of the manuscript describes the development of a novel photothermal technique based on thermoelectric effect. This technique is particularly useful for thermally characterizing thermoelectric materials without using a separate sensor for measuring induced temperature changes. A theoretical and experimental study is presented. The experiments are done on polyaniline - carbon nanotube composite pellets by measuring Seebeck voltage generated by the samples upon heating by a modulated laser beam. Additional infrared radiometry experiments are done on the same samples and the results are in good agreement with those previously found. Later on, the possibility of photothermoelectric materials to be used as sensors for finding thermal transport properties of materials with a thermal wave resonant cavity is suggested.

This thesis has addressed several of the fundamental challenges in correlating the structure thermal transport properties of complex nanoporous polycrystalline zeolite materials. Two types of zeolite materials, MFI and LTA, were employed in order to investigate the effects of temperature and both the framework and non-framework cations on the thermal conductivity of zeolite. The thermal conductivity values of both materials were measured using a well intergrown zeolite film 3-omega method. The thermal transport mechanisms in these materials were investigated by separately analyzing the contributions of different phonon scattering processes. This thesis represents our progress towards a robust framework for understanding and predicting thermal transport properties of zeolite materials and complex crystals in general. Furthermore, the important roles of boundary and defect scattering, as illustrated in this thesis, also imply that the thermal conductivity of zeolite materials can be tuned by exploiting not only the composition but also the pore structure. In addition, a non-equilibrium molecular dynamics simulation with external force was developed and employed to predict the thermal conductivity of materials. It has shown that this method can accurately predict the thermal conductivity of simple materials, such as argon and quartz; however, it failed to predict the thermal conductivity of complex materials, such as zeolite. This thesis presents possible factors that can explain the phenomena and future recommendations to elucidate this issue.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-07T14:31:23Z No. of bitstreams: 1 alisonarantesgoncalves.pdf: 9032611 bytes, checksum: 93776f55ce3ecc6dc5c2e6997dc1283a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T13:23:26Z (GMT) No. of bitstreams: 1 alisonarantesgoncalves.pdf: 9032611 bytes, checksum: 93776f55ce3ecc6dc5c2e6997dc1283a (MD5) / Made available in DSpace on 2016-07-13T13:23:26Z (GMT). No. of bitstreams: 1 alisonarantesgoncalves.pdf: 9032611 bytes, checksum: 93776f55ce3ecc6dc5c2e6997dc1283a (MD5) Previous issue date: 2016-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta tese estudamos a estrutura de bandas de fônons e a condutividade térmica de cristais fonônicos em temperaturas sub-Kelvin. O espectro fonônico de baixas frequências (até dezenas de GHz) foi obtido da solução da equação de onda generalizada através do método de Expansão em Ondas Planas. Os resultados para estruturas com periodicidade bidimensional da ordem de mícrons apresentam band gaps e faixas estreitas de transmissão. Este comportamento é interessante para o controle de vibrações mecânicas como em um filtro de frequências operando na frequência de GHz. A densidade de estados foi calculada com o objetivo de estudar problemas de transporte envolvendo materiais fonônicos. Além disso, calculamos a condutividade térmica cumulativa no regime de temperaturas de sub-Kelvin em micro cristais fonônicos visando possíveis aplicações em materiais termoelétricos. Esses cálculos se baseiam na teoria de transporte de Boltzmann a baixas temperaturas a fim de enfatizar o papel dos fônons de baixa frequência e negligenciar o espalhamento fônon-fônon. Em acordo com resultados recentes na literatura, mostramos que a condutividade térmica cumulativa das estruturas fonônicas cai acentuadamente em relação a suas matrizes (bulk). Dependendo da estrutura esta redução pode ser atribuída à velocidade de grupo dos fônons, à densidade de estados ou à presença de band gaps completos. / In this thesis we have studied the phononic band structure and the thermal conductivity of phononic crystals at sub-Kelvin temperatures. The low-frequency phonon spectra (up to tens of GHz) were obtained by solving the generalized wave equation with the Plane Wave Expansion method. The results for structures with two dimensional periodicity of the order of micrometers show the presence of GHz band gaps and narrow pass band. Such behavior is suitable for mechanical vibrations management like a GHz transversal phononic band pass filter. The phonon density of states was calculated aiming the study in transport problems involving phononic materials. Moreover, we have calculated the cumulative thermal conductivity at sub-Kelvin temperature regime of micro-phononic crystals aiming possible applications in thermoelectrics materials. The calculations were based in Boltzmann transport theory at low temperatures in order to highlight the role of low-frequency thermal phonons and to neglect phonon-phonon scattering. In accordance with recent results in the literature, our findings show that the cumulative thermal conductivity of the phononic crystals drops dramatically when compared with their bulk counterpart. Depending on the structural composition this reduction may be attributed to the phonon group velocity, the density of states or the presence of complete band gaps.

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In dieser Arbeit wurden mit Hilfe von Transportmessungen – vor allem mit thermischem Transport bei sehr tiefen Temperaturen – intermetallische Seltenerdverbindungen untersucht. Diese Materialien sind oft durch starke elektronische Korrelationen gekennzeichnet, die zu neuartigen Eigenschaften führen. Um die Wechselwirkungen in den untersuchten Systemen zu beeinflussen, führten wir ein Magnetfeld als zusätzlichen Parameter ein. Damit untersuchten wir drei Fragestellungen. Im ersten Teil überprüften wir die Gültigkeit des Wiedemann-Franz-Gesetzes in YbRh2Si2. Dieses Material zeigt einen durch ein kleines Magnetfeld induzierten quantenkritischen Punkt, für dessen unkonventionelle Eigenschaften es noch keine allgemein etablierte mikroskopische Theorie gibt. Mit Hilfe des Wiedemann-Franz-Gesetzes haben wir untersucht, ob eine solche Theorie im Rahmen des Quasiteilchenbildes formuliert werden kann. Während wir eine Bestätigung für Magnetfelder abseits des quantenkritischen Punktes zeigen, ergibt unsere Analyse direkt am quantenkritischen Punkt eine Verletzung des Weidemann-Franz-Gesetzes. Dies hat weitreichende physikalische Folgen, da eine Verletzung den Zusammenbruch des Konzeptes von Quasiteilchen impliziert. In der zweiten Studie untersuchten wir die Kondogittersysteme YbRh2Si2 und CeRu2Si2 in Magnetfeldern mit Energien von der Größenordnung der Kondotemperatur. Beide Systeme zeigen bislang ungeklärte feldinduzierte Übergänge mit sehr unterschiedlichen Signaturen jedoch den selben Vorschlägen für deren Ursache: ein abrupter Zusammenbruch des Kondoeffekts oder ein Lifshitzübergang. Mit Thermokraft- und Widerstandsmessungen konnten wir für CeRu2Si2 zeigen, dass auch der thermische Transport kompatibel mit einem Lifshitzübergang ist. Ein globales Modell, das thermodynamische Größen mit einschließt, ist jedoch weiterhin nicht vorhanden. In YbRh2Si2 detektierten wir anstatt eines einzelnen, insgesamt drei Übergänge in höheren Magnetfeldern. Mithilfe einer sehr guten Übereinstimmung von renormalisierten Bandstrukturrechnungen mit unseren und früheren Experimenten, können wir die Entwicklung von YbRh2Si2 im Magnetfeld als Superposition von einer stetigen Unterdrückung des Kondoeffekts und drei Lifshitzübergängen beschreiben. Im dritten Projekt untersuchten wir den supraleitenden Ordnungsparameter von LaPt4Ge12. Während frühere Experimente auf konventionelle Supraleitung hindeuten, wird für das eng verwandte PrPt4Ge12 unkonventionelle und/oder Multiband-Supraleitung diskutiert. Resultate an der Substitutionsreihe LaxPr1-xPt4Ge12 suggerieren jedoch kompatible Ordnungsparameter für beide Verbindungen. Unsere Ergebnisse der spezifischen Wärme und der temperatur- und feldabhängigen Wärmeleitfähigkeit an LaPt4Ge12 sind kompatibel mit dem Modell konventioneller Supraleitung ohne Nullstellen im der supraleitenden Bandlücke. Die Abhängigkeit der Wärmeleitfähigkeit vom Feldwinkel zeigt unerwartet umfangreiche Oszillationsmuster. Während solche Oszillationen oft als Zeichen von Nullstellen in der Bandlücke interpretiert werden, konnten wir die meisten Frequenzen anderen Ursachen zuordnen. Eine sehr genaue Analyse von winkelabhängigen Messungen ist daher unabdingbar, um daraus Schlussfolgerungen für den Ordnungsparameter ziehen zu können.

Thermal conductivity and thermopower measurements in strongly correlated electron systems at low temperatures

The control of low dimensional materials holds potential for revolutionizing the electronic, thermal, and thermoelectric materials engineering. Through strategic manipulation and optimization of these materials, unique properties can be uncover which enable more efficient and effective materials development. Towards the determination of nanoscale strategies to improve the electronic and phononic devices, computational simulations of modified low dimensional materials have been carried in this research. First, the electronic properties of chemically func tionalized phosphorene monolayers are evaluated with spin-polarized Density Functional Theory, as a potential method to tune their electronic properties. The functionalization not only leads to formation of additional states within the semiconducting gap, but also to the emergence of local magnetism. The magnetic ground state and electronic structure are investigated in dependence of molecular coverage, lattice direction of the molecular adsorption and molecule type functionalization. Furthermore, the physical and transport properties of phosphorene grain boundaries under uniaxial strain are evaluated by the use of Density Functional based Tight Binding method in combination with Landauer theory. In both grain boundary types, the electronic bandgap decreases under strain, however, the respective thermal conductance is only weakly affected, despite rather strong changes in the frequency-resolved phonon transmission. The combination of both effects results in an enhancement in the thermoelectric figure of merit in the phosphorene grain boundary systems. Finally, the thermoelectric properties of carbon nanotubes peapod heterostructures are studied and compared to pristine nanotubes using also the Density Functional based Tight Binding method and Landauer theory. It is found that the fullerene encapsulation modifies the electron and phonon transport properties, causing the formation of electronic channels and the suppression of vibrational modes that lead to an improvement of the thermoelectric figure of merit. The results of this thesis highlight the potential of strategic manipulation and optimization of low dimensional materials in improving their unique electronic and thermal properties, revealing promising avenues for improving electronic and phononic devices.:ABSTRACT i ZUSAMMENFASSUNG ii ACKNOWLEDGEMENT iv LIST OF FIGURES ix LIST OF TERMS AND ABBREVIATIONS xviii 1 Introduction 1 1.1 Motivation 1 1.2 Objectives and outline 6 2 Computational Methods 8 2.1 Density Functional Theory 8 2.1.1 The Many-Body System Hamiltonian and the Born-Oppenheimer approximation 9 2.1.2 Thomas-Fermi-Dirac approximation model 10 2.1.3 The Hohenberg-Kohn theorems 12 2.1.4 The Kohn-Sham orbitals equations 13 2.1.5 Exchange-correlation functionals 15 2.2 Density Functional Based Tight Binding method 16 2.2.1 Tight-binding formalism 17 2.2.2 From DFT to DFTB 20 2.2.3 Parametrization 22 2.3 Atomistic Green’s functions 23 2.3.1 Non-Equilibrium Green’s functions for modeling electronic transmission 23 2.3.2 Non-equilibrium Green’s function for modeling thermal transmission 27 3 Tuning the electronic and magnetic properties through chemical functionalization 3.1 Introduction 33 3.1.1 Black phosphorus as a 2D material 33 3.1.2 Chemical Functionalization of low dimensional systems 35 3.1.3 Bipolar Magnetic Semiconductors 36 3.2 Computational approach 38 3.3 Interface effects in phosphorene by OH functionalization 39 3.3.1 Single molecule functionalization 39 3.3.2 Lattice selection 43 3.3.3 Coverage 45 3.4 Chiral functionalization effect in phosphorene 48 3.5 Functionalizing phosphorene towards BMS 51 3.6 Summary 53 4 Tuning transport properties through strain and grain bound-aries 4.1 Introduction 54 4.1.1 Strain in low dimensional materials 54 4.1.2 Grain boundaries 56 4.2 Computational approach 58 4.2.1 Molecular systems 58 4.2.2 Electron and phonon transport and thermoelectric figure of merit 58 4.3 Structural modification by strain in GB systems 60 4.4 Electronic structure modification by strain in GB systems 63 4.5 Thermal transport modification by strain in GB systems 65 4.6 Thermoelectric figure of merit of strained GB systems 68 4.7 Summary 71 5 Tuning transport properties through hybrid nanomaterials: CNT peapods 73 5.1 Introduction 73 5.1.1 Carbon-based nanostructures 73 5.1.2 CNT peapods as hybrid nanomaterials 76 5.2. Computational details 77 5.2.1 CNT peapod model 77 5.2.2 Quantum transport methodology 78 5.3 Structural properties of CNT peapods 79 5.4 Electronic properties of CNT peapods 80 5.5 Thermal properties of CNT peapods 83 5.6 Thermoelectronic properties of CNT peapods 85 5.7 Summary 88 6 Conclusions and outlook 91 Appendices Appendix A Supplementary information to phosphorene functionalization A.1 Spin resolved density of states of 1-OH system 96 A.2 Spin valve model 97 Appendix B Supplementary information to phosphorene grain boundaries 98 B.1 Projected Phonon Density of States in GB1 98 B.2 Thermoelectric transport properties of GB2 99 Appendix C Supplementary information to CNT peapods 101 C.1 Geometry optimization of CNT peapods with larger CNT diameter 101 C.2 Additional analysis of electron transport properties 102 C.3 Phonon band structure of different CNT structures 104 C.4 Additional analysis of thermoelectric performance 105 REFERENCES 105 LIST OF PUBLICATIONS 131 PRESENTATIONS 132 / Die Kontrolle niedrigdimensionaler Materialien birgt das Potenzial für eine Revolutionierung der elektronischen, thermischen und thermoelektrischen Technologien. Durch strategische Manipulation und Optimierung dieser Materialien können einzigartige Eigenschaften aufgedeckt werden, die eine effizientere und effektivere Materialentwicklung ermöglichen. Um Strategien im Nanobereich zur Verbesserung elektronischer und phononischer Bauelemente zu ermitteln, wurden in dieser Forschungsarbeit rechnerische Simulationen modifizierter niedrigdimensionaler Materialien durchgeführt. Zunächst werden die elektronischen Eigenschaften von chemisch funktionalisierten Phosphoren-Monoschichten mit Hilfe der spinpolarisierten Dichtefunktionaltheorie als potenzielle Methode zur Abstimmung ihrer elektronischen Eigenschaften bewertet. Die Funktionalisierung führt nicht nur zur Bildung zusätzlicher Zustände innerhalb der halbleitenden Lücke, sondern auch zum Auftreten von lokalem Magnetismus. Der magnetische Grundzustand und die elektronische Struktur werden in Abhängigkeit von der molekularen Bedeckung, der Gitterrichtung der molekularen Adsorption und der Funktionalisierung des Moleküls untersucht. Darüber hinaus werden die Transporteigenschaften von Phosphoren-Korngrenzen unter uniaxialer Belastung mit Hilfe der auf Dichtefunktionen basierenden Tight-Binding-Methode in Kombination mit der Landauer-Theorie untersucht. In beiden Korngrenzentypen nimmt die elektronische Bandlücke unter Dehnung ab, die jeweilige Wärmeleitfähigkeit wird jedoch nur schwach beeinflusst, trotz ziemlich starker Änderungen in der frequenzaufgelösten Phononentransmission. Die Kombination bei der Effekte führt zu einer Erhöhung der thermoelektrischen Leistungszahl in den Phosphorkorngrenzensystemen. Schließlich werden die thermoelektrischen Eigenschaften von Kohlenstoffnanoröhren-Peapod-Heterostrukturen untersucht und mit denen von reinen Nanoröhren verglichen, wobei auch die auf Dichtefunktionen basierende Tight-Binding-Methode und die Landauer-Theorie verwendet werden. Es wird festgestellt, dass die Fullereneinkapselung die Elektronen- und Phononentransporteigenschaften modifiziert und die Bildung von elektronischen Kanälen und die Unterdrückung von Schwingungsmoden bewirkt, was zu einer Verbesserung der thermoelektrischen Leistungszahl führt. Die Ergebnisse dieser Arbeit verdeutlichen das Potenzial der strategischen Manipulation und Optimierung niedrigdimensionaler Materialien zur Verbesserung ihrer einzigartigen elektronischen und thermischen Eigenschaften und zeigen vielversprechende Wege zur Verbesserung elektronischer und phononischer Bauteile auf.:ABSTRACT i ZUSAMMENFASSUNG ii ACKNOWLEDGEMENT iv LIST OF FIGURES ix LIST OF TERMS AND ABBREVIATIONS xviii 1 Introduction 1 1.1 Motivation 1 1.2 Objectives and outline 6 2 Computational Methods 8 2.1 Density Functional Theory 8 2.1.1 The Many-Body System Hamiltonian and the Born-Oppenheimer approximation 9 2.1.2 Thomas-Fermi-Dirac approximation model 10 2.1.3 The Hohenberg-Kohn theorems 12 2.1.4 The Kohn-Sham orbitals equations 13 2.1.5 Exchange-correlation functionals 15 2.2 Density Functional Based Tight Binding method 16 2.2.1 Tight-binding formalism 17 2.2.2 From DFT to DFTB 20 2.2.3 Parametrization 22 2.3 Atomistic Green’s functions 23 2.3.1 Non-Equilibrium Green’s functions for modeling electronic transmission 23 2.3.2 Non-equilibrium Green’s function for modeling thermal transmission 27 3 Tuning the electronic and magnetic properties through chemical functionalization 3.1 Introduction 33 3.1.1 Black phosphorus as a 2D material 33 3.1.2 Chemical Functionalization of low dimensional systems 35 3.1.3 Bipolar Magnetic Semiconductors 36 3.2 Computational approach 38 3.3 Interface effects in phosphorene by OH functionalization 39 3.3.1 Single molecule functionalization 39 3.3.2 Lattice selection 43 3.3.3 Coverage 45 3.4 Chiral functionalization effect in phosphorene 48 3.5 Functionalizing phosphorene towards BMS 51 3.6 Summary 53 4 Tuning transport properties through strain and grain bound-aries 4.1 Introduction 54 4.1.1 Strain in low dimensional materials 54 4.1.2 Grain boundaries 56 4.2 Computational approach 58 4.2.1 Molecular systems 58 4.2.2 Electron and phonon transport and thermoelectric figure of merit 58 4.3 Structural modification by strain in GB systems 60 4.4 Electronic structure modification by strain in GB systems 63 4.5 Thermal transport modification by strain in GB systems 65 4.6 Thermoelectric figure of merit of strained GB systems 68 4.7 Summary 71 5 Tuning transport properties through hybrid nanomaterials: CNT peapods 73 5.1 Introduction 73 5.1.1 Carbon-based nanostructures 73 5.1.2 CNT peapods as hybrid nanomaterials 76 5.2. Computational details 77 5.2.1 CNT peapod model 77 5.2.2 Quantum transport methodology 78 5.3 Structural properties of CNT peapods 79 5.4 Electronic properties of CNT peapods 80 5.5 Thermal properties of CNT peapods 83 5.6 Thermoelectronic properties of CNT peapods 85 5.7 Summary 88 6 Conclusions and outlook 91 Appendices Appendix A Supplementary information to phosphorene functionalization A.1 Spin resolved density of states of 1-OH system 96 A.2 Spin valve model 97 Appendix B Supplementary information to phosphorene grain boundaries 98 B.1 Projected Phonon Density of States in GB1 98 B.2 Thermoelectric transport properties of GB2 99 Appendix C Supplementary information to CNT peapods 101 C.1 Geometry optimization of CNT peapods with larger CNT diameter 101 C.2 Additional analysis of electron transport properties 102 C.3 Phonon band structure of different CNT structures 104 C.4 Additional analysis of thermoelectric performance 105 REFERENCES 105 LIST OF PUBLICATIONS 131 PRESENTATIONS 132

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