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Computer Modelling of Silicon Single Junction And Tandem Solar Cells
Full text linkIn this thesis it has been used the detailed electrical-optical model Amorphous Semiconductor Device Modelling Programme (ASDMP), ab-initio in its electrical part, to understand and optimise the performance of various types of single and multi-junction solar cells
that have the potential of producing high stabilised conversion efficiency at a reduced cost relative to standard wafer based crystalline silicon (c-Si) cells. In Part-I, dealing with PIN cells, we first explained why the open circuit voltage (Voc) of hydrogenated microcrystalline silicon (μc-Si:H) cells in general declines with increasing crystalline volume fraction, while the limiting
cases of large-grained fluorinated microcrystalline silicon PIN cells and the standard mono-c-Si P/N cells show increased Voc. We have also studied hydrogenated amorphous silicon (a-Si:H)
and μc-Si:H cell behaviour under variable light intensity. We next compared the performance of standard diffused P/N junction c-Si solar cells to “Heterojunction with Intrinsic Thin Layer”
(HIT) cells at different ambient temperatures and showed that while HIT cells are well-adapted for use in hot regions, the former is better-suited for low temperature applications. As the
performance of HIT cells is adversely affected by the defects on the wafer surface, we have modelled the photo-luminescence intensity from HIT cells to quantify these defects. Finally we
have shown that a minimum of 5 μm thickness of a c-Si film, epitaxially grown by PECVD on a c-Si wafer at ~165˚C, is necessary to make cells based on this material feasible for high efficiency applications.Research was conducted under the supervision of Prof. Parsathi Chatterjee of ERU under the SPS [School of Physical Sciences]Research was carried out under IACS fellowship gran
Shape Control Synthesis And Application Of Alloyed And Heterostructured Nanomaterials
Full text linkThis thesis aims at achieving superior control over the synthesis of different nanomaterials with size, shape, composition varaiation and their heterostructure to attain superior photophysical properties and investigation of their applicability in the field of catalysis, phosensing, photovoltaic and photoploraization depending upon suitable material propertiesResearch was conducted under the supervision of Prof. Somobrata Acharya of CAM under SPS [School of Physical Sciences]Research was carried out under the CSIR fellowship and gran
Carbon-Dot Based Hybrid Nanomaterials: Synthesis and Spectroscopic Investigation
Full text linkRecently, carbon dots have gained a prosperous interest due to their versatile applicability
in the field of optoelectronics, biomedicine, sensing and catalysis. Low-toxicity, high photostability,
high aqueous solubility of carbon dots make it a perfect alternative over traditional
quantum dots. The origin of photoluminescence property is not clearly understood yet. It is
believed that the conjugated core and the surface groups are responsible for the fluorescence
property. These materials are promising for optoelectronic applications because of their electron
accepting and donating properties. Therefore, we develop various synthesis methods for
luminescent carbon dots and understand the origin and tuning of optical properties by using spectroscopy. Then, various carbon dots based hybrid nano-composites are designed to find out their potential applicability in energy transfer based light harvesting systems and photovoltaics.Research was conducted under supervision of Prof. Amitava PatraResearch was carried out under the CSIR fellowship and gran
Unconventional fractional quantum Hall states in the lowest Landau Level
Full text linkWe have performed a theoretical search for the incompressible fractional quantum Hall
e ect (FQHE) states in the partially lled lowest Landau level (LL), where the lling
factor lies within the range 2=7 < < 2=5. Incompressibility has been proved by
calculating energy spectrum at fully spin polarized 3/8, 3/10, 4/11, 4/13, 5/13 and
5/17 llings and at partially spin polarized 3/8 lling of the lowest LL. After nding
the appropriate incompressible states, we have calculated their collective modes of
excitation in a single mode approximation. This thesis is consisting of six chapters,
organized as follows.The research was carried out under supervision of Prof. S S Mondal of the Theoretical Physics division under SPS [School of Physical Sciences]The research was conducted under CSIR grant and fellowshi
Structural and Functional modeling of heme Enzymes
Full text linkBio-inorganic chemistry is the basic backbone of human body. Human body consist of several numbers of the enzymes, different enzymes have their different properties and reactivities. We are surviving because of different enzymes activities. Human societies are now running for controlling the Mother Nature. They have tried for the decades to develop those active site enzymes structures which have direct catalytic effects on energy associated relevance to the society. i.e some of the active site structures are directly hydroxylate inert C-H bond that can serves as energy sources for society. This thesis titled „Structural and Functional modelling of Heme enzymes‟ contains detailed understanding of structural view point of the synthetic heme enzymes such as cyt-P450 and some of its applicationsResearch was conducted under supervision of Dr. Avishek Dey, Inorganic Chemistry division under SCS [School of Chemical Sciences]Research was sponsored under DST projec
Studies of Multi-functional Metal-Organic Frameworks and Complexes using Polycarboxylic Acids and pyrazole based Ligands
Full text linkThe design and synthesis of polyhedral coordination cages1 has become a major part of research endeavour in recent years. The supramolecular coordination complexes (SCCs) refer to discrete metallacycles and metallacages which can be obtained by self-assembly reactions. A coordination cage can be defined as a type of coordination compounds with cavities that can engage in host-guest chemistry.2 They usally consist of several metal centres connected with organic ligands. Early efforts in the development of coordination-driven self-assembly reactions and the formation of SCCs were largely structural in nature. The major aim to achieve specific metallacycles and cages through various, now well-defined, assembly strategies including edge-directed, face-directed, symmetry-adapted, and weaklink approaches, all unified under the theme of ―directional bonding‖. Many of these methods are rooted in two component assemblies, wherein one metal acceptor and one organic donor are used in specific ratios to form highly symmetric metallacycles or cages, with examples spanning many polygons and polyhedra. The metallacycles and metallacages are very useful in host-guest chemistry, apart from that they are also well documented in the literature in molecular sensors, in luminescence, molecular optics, magnetism, homo and heterogeneous catalysis etc.The studies of polynuclear lanthanide based cage complexes are at the early stage of research. Polynuclear lanthanide cages or clusters have attracted research interest because of their versatile architecture (geometry) and photophysical properties. Polynuclear lanthanide cages or clusters have widespread applications in sensors, labels for biomolecules, stains for cellular imaging, display devices, redox-active switches, magnetocaloric effects and single molecule magnets (SMMs). Due to the magnetic anisotropy arising from large unquenched orbital angular momentum and unpaired f-electrons lanthanide complexes (especially Dy) are excellent candidate for the high energy barrier for reversal of magnetization.3 On the other hand, molecular magnetic materials which show large magnetocaloric effect (MCE)4 are of
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immense research interest for their cryogenic applications. Gd3+ ion one of the most
commonly found element which are well documented in the literature having large magneto caloric effect (MCE). Such kind of fascinating properties arises due to large spin-only magnetic moment (S=7/2), quenched orbital momentum and weak super exchange interactions which is responsible for a large entropy change. Therefore it has been found that Gd(III) based complexes showed super cooling properties for magnetic based coolants with
highly entropy change value.The research was conducted under the supervision of Dr. Raju Mondal of Inorganic Chemistry under SCS [School of Chemical Sciences]The research was conducted under CSIR grant and fellowshi
Multifunctional Polymers by Polymer Modification Using ATRP Technique
Full text linkThe present thesis work entitled “Multifunctional Polymers by Polymer
Modification Using ATRP Technique” deals with the synthesis of
multifunctional polythiophene (PT) based graft copolymer by grafting from
approach using simple and cost effective atom transfer radical polymerization
(ATRP) technique. The grafting upon PT has been done by different
hydrophilic and hydrophobic polymers having various functional group(s).
This thesis also describes the synthesis of stimuli responsive water soluble 2
arm/3 arm random and block copolymer. The versatile applications of these
types of multifunctional polymers for the fabrication of molecular device,
molecular thermometer, sensor, drug delivery vehicle etc. have been
introduced here.Research was carried out under the supervision of Prof. A K Nandi, PSU under SCS [School of Chemical Sciences]Research was conducted under DST INSPIRE Fellowship Progra
Templated And Non Templated Synthesis Of Microporous And Mesoporous Phosphate Based Molecular Sieves
Full text linkPorous materials have drawn immense attention because of their high surface area, tunable and well defined pore size and shape, diverse chemical composition leading to wide range of applications. These materials contribute greatly in the fields of catalysis, gas adsorption and separation, ion exchange, drug delivery, solar cells and many other emerging applied fields. Among the different types of porous materials, metal phosphates are a fascinating subclass for their diverse applications. But low surface area and small pore size of phosphate based materials remain as major problems. In this particular research work our aim was concentrated to delve into the unexplored area of phosphate based molecular sieves.Research was carried out under the supervision of Prof. Asim Bhaumik of Materials Science. The scholar was under Inorganic Chemistry division under SCS [School of Chemical Sciences]Research was conducted under CSIR research & fellowship gran
Structural Aspects of Proteins and Protein-Protein Assemblies at Single Molecule Level using Scanning Probe Microscopy Approach
Full text linkThe research work embodied in the present thesis entitled “Structural Aspects of Proteins and Protein-Protein Assemblies
at Single Molecule Level using Scanning Probe Microscopy Approach” deals with proteins/protein-protein complexes that are
known to be important in biological events like DNA transcription, DNA packaging etc., but whose tertiary structures are not known yet. One of such protein is p300, which is a transcriptional coactivator
having important role in different cellular processes. Scanning probe microscopy has been applied to probe the structural features of this protein and the complexes between p300 and some of its important target proteins, e.g., p53, histone and HMGB1. The thesis work has been presented in six chapters. Chapter 1 provides a general background on functions of proteins
and structure-function correlation, established biophysical techniques to probe the protein structure, and necessity of the single molecule approaches for studying biomolecular structure and behaviour. In
addition, this chapter presents basic information on the proteins employed, and the basic operational principles of the
biochemical/biophysical techniques applied in the present thesis.
Chapter 2 describes the applicability of scanning probe microscopy approach for investigating biomolecules at the single molecule level. The capability of this approach has been exemplified in several
specific cases, i.e., in probing mechanical and electronic properties of the iron-storage protein ferritin, in eliciting the precise DNA structural changes that are induced by binding of platinum anticancer drugs/agents in the presence of HMGB1 protein, and in delineating the structural aspects of the complex between DNA polymerase klenow fragment and dsDNA. These confidence-building exercises have effectively served towards establishing our AFM single molecule detection setup, prior to performing experiments on protein/protein-
protein complexes of unknown structure(s). Chapter 3 presents the structural features of human histone acetyltransferase p300 and its complex with p53, as revealed by atomic force microscopy. In this chapter, the overall shape and major structural signatures of the full-length p300 protein have been discussed. It is found that p300 FL is almost prolate ellipsoidal in
shape, having several bulges. Functionally important N-terminal and C-terminal regions have been identified by applying domain-specific antibodies. Furthermore, the binding region of p53 protein on p300 FL has been located. Chapter 4 provides information on the binding location of the
chromatin protein histone on p300 FL. In this chapter, the plausible location of bromo and HAT domain of p300 FL has been identified. The interactions between p300 FL and octameric histone/histone H3 in both acetylating and non-acetylating conditions have been probed by applying single molecule atomic force spectroscopy. Chapter 5 discusses the binding of HMGB1 protein on p300 FL. It is observed that HMGB1 binds at the central region of p300 FL. Force of interaction operating between these two proteins both in acetylating and non-acetylating medium has been probed by force spectroscopic method. The mechanism of unbinding process between them has been monitored by dynamic force spectroscopy. Chapter 6 provides a general conclusion and scopes for more advanced experiments.Research was conducted under the supervision of Prof. Rupa Mukhopadhyay of Biological Chemistry division under SBS [School of Biological Sciences]Research was carried out under CSIR fellowshi
Structural, dielectric and magnetic properties of some promising multiferroic oxides
Full text linkMultiferroic transition metal oxides with intertwined and coupled physical prop-
erties are active area of research due to their immense possibilities in technological
applications. Multiferroic materials easily respond to the thermodynamic param-
eters by exhibiting changes in order parameters. These unusual changes become
interesting when the coupling is observed near the room temperature. In this
thesis Cr2O3, SmCrO3 and HoCrO3 have been systematically investigated. Their
structural, dielectric, ferroelectric and magnetic properties are studied in bulk as
well as thin film configuration. Detailed structural study has been performed us-
ing X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Elec-
trical properties are investigated using ac as well dc electric field. Magnetization
analysis confirmed the magnetic nature of the samples. Most interestingly, the
coupled effect has been observed by measuring dielectric properties in presence
of magnetic field. Possible presence of electro-magnetic coupling near room tem-
perature is promising for technological applications for memory devices.Research was carried out under the supervision of Prof. Sourav Giri of the Solid State Physics division under SPS [School of Physical Sciences]Research was conducted under IACS fellowship and DST research gran