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Perspectives of chalcopyrite-based CIGSe thin-film solar cell: a review
Get PDFSolar photovoltaic (PV) is empowering, reliable, and ecofriendly technology for harvesting energy which can be assessed from the fact that PV panels with total electricity generation capacity of 505 GW have been installed by the end of 2018. Thin-film solar cells based on copper indium gallium selenide (CIGSe) are promising photovoltaic absorber material owing to an alternative to crystalline silicon (c-Si)-based solar cells because of the huge potential for low-cost solar electricity production with minimal usage of raw materials. The efficiency record of 23.4% was achieved recently in CIGSe solar cells, which was comparable to c-Si solar cells (27.6%). The manufacturing cost of $0.34/W is expected for 15% efficient CIGSe module. The present review article discusses the perspectives of CISe/CIGSe-based thin-film solar cells with the focus on absorber material. Different vacuum and non-vacuum techniques for fabricating these materials are discussed along with the operation of solar cells and their manufacturability. The working mechanism of CIGSe solar cells with the characteristic features of the open-circuit voltage and current density as well as the factors influencing the efficiency in different fabrication techniques are reviewed. Moreover, some strategies toward the improvement of solar cells performance contemplating modified deposition are reviewed. Furthermore, how these strategies can be executed in order to make it cost effective methods is also discussed in detail. Prevailing constrictions for the commercial maturity are deliberated, and future perspectives for improvement at lab as well as industrial scalabilities are outlined
Fullerene (C-60)-modulated surface evolution in CH(3)NH(3)PbI(3)and its role in controlling the performance of inverted perovskite solar cells
Get PDFWe report here the effect of fullerene (C-60) incorporation on the growth of CH(3)NH(3)PbI(3)perovskite crystals and the effect on photovoltaic performance of perovskite solar cells (PSCs) prepared in inverse geometry. Incorporation of C(60)induced the growth of larger gains and compact thin film of perovskite with reduced defects, which led to its enhanced photovoltaic performance. Apart from that, C(60)also participates in transportation and collection of photo-generated electrons. The optimum incorporation of C(60)resulted in an impressive improvement in the power conversion efficiency (PCE) of champion PSC from 9.2 to 12.8%. Moreover, the C-60-doped PSCs exhibited improved air stability compared to undoped devices. The enhanced PCE in C-60-doped PSCs is a result of enhanced optical absorption and separation of photo-generated charge and their transportation in the active layer. Since the size of C(60)molecules is of the order of nm, they easily get filled into the perovskite voids and facilitate another percolation path ways for charge carriers to transport and suppress the recombination losses via passivating the recombination centres in perovskite layers. The compact perovskite layer with larger grains led to reduced inter-granular grain boundaries with reduced defects, which restricts the fast diffusion of moisture into active layer and resulted in improved stability in device performance
Improved Electromagnetic Interference Shielding Response of Polyaniline Containing Magnetic Nano-ferrites
Get PDFImprovement of electromagnetic interference (EMI) shielding materials with miniaturization of devices is an important area of research in various applications like communication, electronic warfare, defense, and different civilian applications. Nano-crystalline ferrite, MFe2O4 (M = Ni, Zn, and Co), powders have been synthesized by sol-gel citrate nitrate precursor method. The crystalline size of samples was found in the range of 20-45 nm as analyzed by XRD and TEM analysis. Polyaniline/ferrite nano-composites with 50 wt% were synthesized by mechanical blending. The structural and magnetic properties of the nano-particles were characterized by using Rietveld analysis of powder X-ray diffraction and vibrating sample magnetometer (VSM) respectively. Using the Rietveld refinement, the goodness of fit, interatomic distance, Bragg contribution, and R factors have been determined. Ferrites and their nano-composites, under applied magnetic field up to 20 KOe, exhibited the hysteresis loops of ferromagnetic nature with maximum saturation magnetization of 51.68 emu/g shown by CoFe2O4. The electromagnetic shielding parameters (various shielding effectiveness and reflection loss) and microwave absorbing properties were measured in X band frequency region (8.2-12.2 GHz). Nano-composites show promising and enhanced EMI shielding behavior with overall highest SE value of 52 dB shown by CoFe2O4 composite
Investigation of Micro-indentation Hardness of Bi2Te3 Based Composite Thermoelectric Materials
Get PDFWe have successfully synthesized Bi0.5Sb1.7Te3+x (x = 0, 0.12, 0.14) composite thermoelectric materials via solid state reaction followed by Spark Plasma Sintering (SPS). The structural characterization of these materials carried out by X-ray diffraction reveals to be composite phase consisting of Bi2Te3-type phase with small amount of Te and Sb phase. The micro-hardness performed on samples Bi0.5Sb1.7Te3+x(x = 0, 0.12, 0.14) reveals the reduction of VHN with increasing Te concentration as compared to that of single phase state-of-the-art Bi0.5Sb1.5Te3 thermoelectric materials
Magnetic Studies on Spinel Ferrite Nanoparticles and Bulk Samples Synthesized by Citrate Combustion Route
Get PDFWe report structural, microstructural and magnetic studies of ZnFe2O4, MnFe2O4 and mixed Mn-Ni-Zn ferrites in nanoparticles and bulk forms. Polycrystalline samples were prepared by citrate combustion synthesis, which resulted in homogeneous and nanograin powders. Particle sizes estimated from the XRD and SEM were found to be below 100 nm for the calcined powders (600 degrees C) and above 300 nm range for the sintered (1200 degrees C) samples. Substitution of Ni and Zn for Mn enhanced the saturation magnetization and coercivity, because of the redistribution between octahedral and tetrahedral iron sites. Curie temperature were found to be higher for the calcined powders as compared to corresponding sintered samples due to particle size effects
Magnetron configurations dependent surface properties of SnO2 thin films deposited by sputtering process
No full textThe effect of balanced magnetron (BM) and unbalanced magnetron (UBM) configurations, in RF sputtering process, on the surface properties of SnO2 thin films has been investigated. X-ray photoelectron spectroscopy (XPS) Sn3d and O1s core spectra reveal that the films deposited at RF power of 250 W under BM configuration consist of Sn4+ oxidation states, while those deposited under UBM configuration consist of Sn4+ and Sn2+ oxidation states. This has been attributed to the migration of oxygen atoms from SnO2, resulting in the formation of Sn interstitial and oxygen vacancies. The contact angle (theta) recordings reveal that the UBM configuration results in more hydrophobic surface (140.6 degrees) of SnO2 thin films than that under BM configuration (129.6 degrees). Further, Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM) results indicate that the SnO2 thin films deposited under UBM configuration have better density with granular grains in comparison to that under BM configuration. The present studies establish the fact that magnetron configurations in sputtering process have significant impact on the surface properties of SnO2 thin films
Performance Analysis of Light-weight Scattering Coefficient Counter with AURORA 3000 Nephelometer over Delhi
No full textFrom past many decades, the integrating nephelometers are generally used to measure the aerosol scattering coefficient for ground level at different wavelengths. In recent years, the research focus has been shifted toward the airborne observations using either tethered balloons or drones. For this particular purpose, one needs light-weight instruments which are capable of measuring the aerosol scattering coefficient suitable for airborne activities. Thus, we report the design and development of a light-weight scattering coefficient counter (weight 500 g, 7 '' x 3 '') with high sensitivity. This instrument has been specifically designed and developed for the measurement of aerosol scattering coefficient at 633 nm wavelength. The aerosol scattering coefficient calculation becomes extremely important for modeling aerosol optical/radiative properties. Delhi is one of the regions with high aerosol loadings, so one needs such Light-weight instruments for the aerosol scattering coefficient measurements. At present, this instrument has only been evaluated at ground level. But, before using the developed instrument for airborne observations, there is a strong need for comparison of the instrument against routinely used nephelometers for performance evaluation. Comparisons were performed between the light-weight scattering coefficient counter and high-end AURORA 3000 Nephelometer for two different seasons. For both the seasons, i.e., the monsoon season (July 25-August 24, 2017) and the winter season (February 1-28, 2018), we found a strong correlation (i.e., R-2 = 0.99). However, the highest value of scattering coefficient was found to be 98 +/- 32 Mm(-1) with a mean value of 55 Mm(-1) for the monsoon season, while the same for the winter season was observed to be 270 +/- 108 Mm(-1) with a mean value of 165 Mm(-1). This light-weight instrument could be a potential instrument for aerosol scattering observations, especially for airborne platforms with payload mass limitations
Gene Expression Profiling of Human Adipose Tissue Stem Cells during 2D versus 3D Adipogenesis
Get PDFMuch of the current understanding on molecular and cellular events of adipose developmental biology comes from monolayer cell culture models using preadipocyte cell lines, although in vivo adipose tissue consists of a much more complex three-dimensional microenvironment of diverse cell types, extracellular network, and tissue-specific morphological and functional features. Added to this fact, the preadipocytes, on which the adipogenesis mechanisms are mostly explored, possess some serious limitations (e.g., time of initial subculture and adipogenic differentiation time), which, perhaps, can efficiently be replaced with progenitor cells such as adipose tissue-derived stem cells (ASCs). With the objective of developing a better in vitro model for adipose developmental biology, this project involves gene expression profiling of human ASCs (hASCs) during their differentiation to adipocytes in a 2D versus 3D culture model. This transcriptional-level analysis revealed that gene expression patterns of adipogenesis-induced hASCs in a 3D self-assembled polypeptide hydrogel are relatively different from the 2D monolayered cells on plastic hard substrate. Moreover, analysis of adipogenic lineage progression 9 days after adipogenic induction shows earlier differentiation of hASCs in 2D over their 3D counterparts. However, differentiation in 2D shows some unexpected behavior in terms of gene expression, which does not seem to be related to adipogenic lineage specification. Since hASCs are already being used in clinical trials due to their therapeutic potential, it is important to have a clear understanding of the molecular mechanisms in an in vivo model microenvironment like the one presented here
Giant ferromagnetism in Li doped ZnO nanoparticles at room temperature
No full textWide band gap diluted magnetic semiconductor nanomaterials with improved magnetic and semiconducting properties have achieved great importance in spintronic technology since last decades. Synthesis of a good quality of magnetic semiconductor at room temperature is still a challenge for material scientist. Herein, we report synthesis of Li doped ZnO nanoparticles (NPs) using chemical precipitation method at room temperature with improved magnetic and semiconducting properties. Structure and phase of ZnO NPs have been confirmed by XRD pattern. Optical band gap of ZnO NPs have been tuned in the range of 3.10-3.34 eV using different percentage of Li doping. Maximum optical band gap in ZnO NPs was found 3.34 eV in ZnOLi-1 sample. It has been found that specific Li doping percentage can enhance magnetic property of ZnO NPs at room temperature. The coercivity of ZnO NPs has been tuned in the range of 317-1570 Oe by Li doping. Saturation magnetization and coercivity have been found maximum 0.055 emu/gm and 1570 Oe in ZnOLi-1 NPs respectively. In this work we have observed that ZnOLi-1 NPs show maximum optical band gap and coercivity. Thus we achieved wide band gap diluted magnetic semiconductor with enhance optical and ferromagnetic property at room temperature in terms of Li doped ZnO NPs
A label-free ultrasensitive microfluidic surface Plasmon resonance biosensor for Aflatoxin B-1 detection using nanoparticles integrated gold chip
No full textThe Surface Plasmon resonance (SPR) based label-free detection of small targeted molecules is a great challenge and require substantial signal amplification for the accurate and precise quantification. The incorporation of noble metal nanoparticles (NPs) like gold (Au) NPs for the fabrication of SPR biosensor has shown remarkable impact both for anchoring the signal amplification and generate plasmonic resonant coupling between NPs and chip surface. In this work, we present comparative studies related to the fabrication of self-assembled monolayer (SAM) and the influence of AuNPs on Au chip for Aflatoxin B-1 (AFB(1)) detection using SPRi apparatus. The SAM Au chip was sequentially modified by EDC-NHS crosslinkers, grafting of protein-A and finally interaction with anti-AFB(1) antibodies. Similar multilayer chip surface was prepared using functionalized lipoic acid AuNPs deposited on SAM Au chips followed by in situ activation of functional groups using EDC-NHS crosslinkers, grafting of protein-A and immobilization of anti-AFB(1) antibodies. This multilayer functionalized AuNPs modified Au chip was successfully utilized for AFB(1) detection ranging from 0.01 to 50 nM with a limit of detection of 0.003 nM. When compared to bare self-assembled Au chip which was shown to exhibit a limit of detection of 0.19 nM and a linear detection ranging from 1 to 50 nM, the AuNPs modified Au chip was proven to clearly be a better analytical tool. Finally, validation of the proposed biosensor was evaluated by spiked wheat samples and average recoveries (93 and 90.1%) were found to be acceptable