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Hen’s eggshell, a biological waste product, was turned into a cell imaging probe: europium doped hydroxyapatite (HAp: Eu) nanoparticle using hydrothermal method. Luminescence of the synthesized nanoparticle was studied for various doping concentrations of the lanthanide ion europium (Eu3+). Eu doped HAp showed a hexagonal crystal structure and rod-shaped morphology. Well-defined emission peaks of europium, corresponding to the substitution of Eu3+ at the Ca2+(I) site of HAp, were confirmed from the samples’ photoluminescence (PL) spectra. Good biocompatibility up to 500 μg/mL of the samples indicates their potential applications in bioimaging. Synthesized nanoparticles were internalized and used for in vitro imaging of the PC12 cells without any surface modification. The materials’ use as a potential in vivo imaging agent is proposed from the haemolysis study.

The realization of highly efficient neuromorphic computing necessitates the development of artificial synaptic devices. This article reports a titanium dioxide (TiO2)-based transparent artificial synaptic device that exhibits almost all functionalities of a biological synapse. The fabricated device exhibits potentiation and depression at very low voltage amplitude (500 mV) input stimuli. The plasticity of the artificial synapse is also studied by varying the number of input stimuli and interval between the pulses (spike-rate-dependent plasticity—SRDP). The transition from short-term plasticity (STP) to long-term potentiation (LTP) is observed for a higher number of input stimuli and shorter interval between pulses. The device possesses excellent paired-pulse facilitation (PPF) with varying width, interval, and amplitude of the input stimuli. The spike-timing-dependent plasticity (STDP), one of the essential characteristics of a biological synapse, is also demonstrated.

In this work, we present a simple and solution-based synthesis approach to combine the virtues of PEDOT:PSS and carbon nanotube (CNT) by developing a composite film and their application as a hole selective layer (HSL) in organic-silicon hybrid heterojunction solar cell. The heterojunction solar cell with the optimised PEDOT: PSS-CNT HSL showed a notable open-circuit voltage ( V oc ) of 588.6 mV, short circuit current density ( J sc ) of 25.3 mA/cm2 and fill factor (FF) of 60.79% yielding a photo-conversion efficiency (η) of 9.05%. The pristine PEDOT:PSS/Si device obtained an η of 6.2% with a V oc of 502 mV. The role of CNT in the charge transport mechanism and improving V oc was corroborated by employing various characterisation methods such as J-V, C-V, and electrochemical impedance spectroscopy. The composite layer induced a strong inversion layer in silicon and enhanced the device performance. The application of PEDOT:PSS-CNT composite film is not limited to c-Si solar cells, but can also be used to fabricate flexible organic and perovskite solar cells.

Boron-doped cuprous oxide (Cu2O:B) thin films were deposited on glass and silicon substrates via radio frequency (rf) magnetron co-sputtering at room temperature using metallic copper and boron targets. The influence of B doping on the morphology of Cu2O was studied using X-ray diffraction and spectrometric techniques. Optical transparency and bandgap of the doped films were improved compared to intrinsic Cu2O thin film. X-ray photoelectron spectroscopy confirms that Cu is in + 1 valance state even after doping. Electrical characteristics suggest enhanced p-type conductivity and reduction in resistivity with boron doping, due to the increase in charge carriers. Cu2O:B/c-Si heterojunction shows good rectifying (~ 104) behavior, and the small ∆Ev and high ∆Ec obtained from the flat band diagram suggests its potential application as hole-selective layer in c-Si solar cell.

A transparent superhydrophilic self-cleaning nanocoating is fabricated and developed by hybridizing anatase TiO2 with graphene sheets. In the hybrid preparation, ellipsoidal TiO2 nanocrystals are grown exclusively over the graphene sheets, exposing high energy {001} and {010}/{100} facets. The hybrid is synthesized by a hydrothermally modified sol-gel method using CTAB (Cetyltrimethylammonium bromide) as the capping agent under an acidic pH 3 and using very low weight percentage of graphene with respect to as grown TiO2. The synthesized samples are studied for its phase, crystallinity, exposed facets, and optical properties using Raman, TEM and DRS UV–vis analyses. During the hydrothermal treatment, the graphene oxide sheets are reduced to graphene layers simultaneously on which in-situ growth of TiO2 nanocrystals takes place. A close chemical contact between both TiO2 and graphene established is confirmed from XRD, XPS and FTIR analyses. The photocatalytic activity studied from degradation of Methylene blue dye is increased by graphene hybridization, with a change in kinetic rate constant k = 9.23 × 10−3 min-1 for pristine TiO2 to 24.7 × 10−3 min-1 for the hybrid. The fabricated nanocoating of the hybrid over a glass substrate showed about 94% transparency throughout the visible region and a superhydrophilic behavior with the water contact ˜0° within 15 min of UV irradiation. The charge transfer mechanism by the reduced recombination rate in the hybrid is clearly investigated by PL spectra and TCSPC techniques.

p-type Cu2O thin films doped with trivalent cation boron are demonstrated for the first time as an efficient hole-selective layer for c-Si heterojunction solar cells. Cu2O and Cu2O:B films were dep...

Tin Sulphide (SnS) thin films were deposited on glass substrate through chemical spray pyrolysis (CSP). Precursor solution was prepared by mixing stannous chloride and thiourea in the ratio 1:4. Influence of substrate temperature was studied. Pure SnS phase was obtained for an optimised deposition temperature of 280 °C. Substrate above and below 280 °C resulted in the formation of other phases such as SnS2, Sn2S3. Structural, electrical and optical properties of the films were determined using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV–VIS-NIR spectrophotometer. The XRD pattern of the film at the optimized condition exhibited polycrystalline orthorhombic structure of SnS with preferential orientation along (1 1 1) plane. The prepared thin films have optical absorption coefficient >104 cm−1in the wavelength rage of 400–800 nm. Phase purity was determined by Raman analysis, which confirmed the formation of single phase SnS film. In this study we could optimise deposition temperature to get SnS with single phase, avoiding unwanted phases like Sn2S3, SnS2 and Sn3S4.

Hen's eggshell, a biological waste product, was turned into a cell imaging probe: europium doped hydroxyapatite (HAp: Eu) nanoparticle using hydrothermal method. Luminescence of the synthesized nanoparticle was studied for various doping concentrations of the lanthanide ion europium (Eu

Present work reports the preparation of WO3 nanoparticles through facile and efficient hydrothermal route. Raman analysis confirms the formation of monoclinic WO3 phase. Scanning electron microscope (SEM) analysis shows that the WO3 samples consists of nano sized particles having uniform distribution and UV–vis-NIR analyses shows absorption in the visible region. Dynamic Light Scattering (DLS) experiments reveal that WO3 nanoparticles have zeta potential of −12.9 mV and electrophoretic mobility of −6.7 × 10−5 cm2/Vs in water. Value of zeta potential confirms that the sample is moderately stable at room temperature. Also these WO3 nanoparticles showed significant sonocatalytic property in methylene blue (MB) solution. WO3 nanoparticles having a concentration of 1 g/L shows a noteworthy 61.2% of removal efficiency on water containing MB dye concentration of 10 mg/L within 90 min.

This paper describes the fabrication of copper oxide and zinc tin oxide complementary inverters where both the p-type and n-type channels were deposited by RF magnetron sputtering. We have designed low-voltage and high gain complementary inverters by combining a set of p channel copper oxide and n channel zinc tin oxide thin film transistors (TFTs) with different aspect ratios, thus reducing the difference in mobility and threshold voltage between both types of TFTs. The complementary inverters with four different geometric aspect ratios were fabricated using top-contact configuration. The voltage gain increase with aspect ratio and a maximum value of 4.2 was reached for an aspect ratio of 2 (Wp:Wn = 7200 μm/3600 μm). The voltage gain was found to be dependent on the SS value of p-type TFTs. It is also noticed that an inverter having a geometric aspect ratio of 2 gave better voltage gain and noise margin values. For a VDD = 20 V the NMH and NML values are 7 V and 6.5 V, respectively.

Electromagnetic safeguards are key factors for electronic devices. Lightweight and highly flexible polymer composite films with high electrical conductivity are considered to be efficient electromagnetic interference (EMI) shielding materials. Polymer composites offer alternative to metal-based composites which have poor flexibility, corrodibility, and are difficult to process. Here, highly flexible polyvinyl alcohol/poly (3, 4-ethylenedioxythiophene):polystyrene sulfonate/multiwalled carbon nanotube (PVA/PEDOT:PSS/MWCNT) free-standing composite films were fabricated by a solution mixing process followed by a simple solvent casting technique. PVA/PEDOT:PSS/MWCNT composite films of thickness around 20 microns showed high EMI shielding effectiveness (SE) in the X-band over the frequency range of 8–12 GHz. Incorporation of MWCNT into the polymer matrix considerably increased the mechanical strength of the PVA/PEDOT:PSS/MWCNT composite free-standing film. This investigation revealed that PVA/PEDOT:PSS/MWCNT composite film with 0.5 wt.% of MWCNT showed excellent absorption-dominated EMI SE of 60 dB over the frequency range of 8–12 GHz with extensive tensile strength. Our study opens a facile way to design flexible, lightweight and free-standing films as EMI shielding for next-generation flexible electronic devices.

Organometallic lead halide perovskites are well known for its excellent and unique light-harvesting properties. This brands them as a promising candidate in almost all the optoelectronic devices. Present work demonstrates the synthesis of methylammonium lead bromide, MAPbBr3 quantum dots (QDs) of diameter less than 4 nm and methylammonium - octylammonium lead bromide core-shell type nanoparticles (CSNPs) with a core diameter of about 1–2 nm surrounded by a shell of thickness 4 nm. The core-shell structure was confirmed from crystal structure analysis – X-ray diffraction pattern, transmission electron microscopy (TEM) images and an increased stokes shift between absorption edge and the photoluminescence emission peak. These core-shell nanoparticles with high photoluminescence quantum yield (PLQY) and color tuning ability were incorporated into poly (methyl methacrylate) (PMMA) matrix to form transparent nanocomposites which were highly stable, with reduced wettability and a high PLQY of 88%. PLQY stability of composites towards humidity was examined by keeping the samples fully immersed in water for 18 h, after which PMMA composites were showing PLQY ∼83%, no considerable difference was found compared to dry composites. Dry films (kept sealed in covers) were found to be relatively stable for about one year retaining PLQY of 13%. The composite films of core-shell particles were used to demonstrate a prototype of down converting light emitting diode (LED), emitting pure green light capable of improving the quality of display devices.

Surface enhanced Raman spectroscopy (SERS) is a versatile and unique technique for the detection and identification of molecules. Over the past few decades this unique technique has grown as a tool for the qualitative and quantitative analysis. We report a novel and simple method for the synthesis of silica‑silver nanospheres (Ag-SiO2) which can be used as colloidal SERS substrate. Geometrically confined hotspots with stable silver nanoparticles are obtained allowing a preferrential arrangement of hotspots. The prepared Ag-SiO2 nanospheres with varying size are used for the SERS detection of Rhodamine 6G. The SERS intensity is found to vary with the change in size of silica and distribution of silver nanoparticles. Both these quantities are optimized to get maximum enhancement of Raman signal and the detection limit is found to be 10−18 M for Rhodamine 6G. Further, the work is extrapolated to an application which involves the SERS detection of Sudan I, a carcinogenic food adulterant, with a detection limit of 10−8 M.

We report the effect of rGO on structural, electrical, spectral and nonlinear optical properties of reduced graphene oxide-polyaniline (rGO-PANI) nanocomposites. The rGO-PANI composites with different concentration of rGO were synthesized through an in situ polymerization method. The structural and optical studies of the composite powders show that the template effect of rGO provides a well ordered structure of PANI with better crystallinity. This may be due to the strong electrostatic, p–p, and hydrogen bond interactions between PANI and rGO materials. The conductivity of the composite material increases with respect to pure PANI up to a particular limit, and then decreases. It is mainly due to the disordered conjugated structure of PANI. The nonlinear optical properties of rGO–PANI composites are evaluated by Z-scan technique using a continuous wave Nd:YAG laser at a wavelength of 532 nm. Two photon absorption is the main mechanism behind the self defocusing nature of rGO - PANI composites. The saturable absorption behavior of the material is due to the depletion of valence band and the band filling effect of sp2 carbon domains. The nonlinear absorption coefficient and refractive index of the samples are also estimated and the results show that rGO-PANI composite material is a promising candidate for the applications in optical switching, optical sensors and in ultrafast photonics

Alternative fuels and modifications in the engine to increase efficiency are receiving much attention nowadays due to the depletion of world petroleum reserves and increased environmental concerns. The desire to reach higher efficiency, lower specific fuel consumption and reduced emissions in internal combustion engines have become the primary focus of engine researchers and manufacturers over the past three decades. In this scenario, processed cooking oil (Biodiesel) with Thermal barrier coated diesel engine becomes an attractive green alternative to the present compression ignition engines. Biodiesel used in the experiment is a methyl ester of free fatty acid made from used cooking oil. The properties of biodiesel fuel are similar to the diesel fuel so that it can work in existing infrastructure of conventional diesel engines without any engine modification. Yttria-stabilized zirconia is used as the Thermal barrier coating. It was found experimentally that B20 was the optimum blend of Biodiesel with Diesel as it had properties comparable to diesel fuel and had lower polluting emissions [29]. Experiments were performed in a Garuda Greaves diesel engine with and without thermal barrier coating for the present work. From the results of the investigation in the diesel engine without thermal barrier coating, it was found that there has been a decrease in brake power with an increase in brake specific fuel consumption for all blends of biodiesel over the entire load range when compared to the diesel fuel. In the case of engine exhaust gas emissions; lower HC, CO and higher CO2 and NOx emissions have been found for all biodiesel blends when compared to diesel. Moreover, reductions in sound level for all biodiesel blends have been observed when compared to diesel. Thermal barrier coatings (T.B.C) help to overcome the limitations possessed by biodiesel in its performance due to its lower heating value when compared to diesel. It also helps to reduce the emissions further when compared to a diesel engine without thermal barrier coating running on biodiesel. Therefore, it can be concluded that B20 with T.B.C was the best arrangement as it showed lower emissions, better properties, and economy than diesel engine without T.B.C

Due to exceptional electronic, optoelectronic and catalytic properties, MoS2 has attracted extensive research interest in various applications. In the present scenario, the exploitation of noble-metal-free catalysts for hydrogen evolution is of great interest. Herein, we report the structural, optical, magnetic and electrocatalytic properties of pure and nickel-substituted MoS2 nanostructures synthesized by the hydrothermal method. X-ray diffraction (XRD) analysis reveals that all samples exhibit the hexagonal structure of MoS2 and the formation of NiS2 at higher concentrations of nickel. Vibrating sample magnetometer (VSM) measurements of the Mo1−xNixS2 nanostructures show a hysteresis loop at room temperature with a higher saturation magnetization for 1% Ni-substituted MoS2 nanostructures, confirming the ferromagnetic behaviour of the sample. The indirect-to-direct band gap transition of few-layered nanostructures was confirmed by the optical absorption spectrum showing bands in the 600–700 nm and 350–450 nm regions. This study also highlights the excitation wavelength-dependent down- and up-conversion photoluminescence of the as-synthesized samples, providing new horizons for the design of MoS2-based optical and spintronic devices. The electrocatalytic effect of 3% Ni-substituted MoS2 nanostructures has been found to be higher than that of other deposit concentrations as it corresponds to the efficient hydrogen evolution reaction (HER).

Metal oxides like MoO 3 , V 2 O 5 , WO 3 and organic compounds like PEDOT:PSS are widely used as carrier selective contacts for solar cell fabrication. Generally, these materials an n-type in nature. Cu 2 O is an earth-abundant, non-toxic, p-type material which is used in many optoelectronic applications. In this work, we report the development of a novel Cu 2 O material by trivalent boron (B 3+ ) ion doping and its implementation as a hole selective layer (HSL) in a c-Si solar cell. The Cu 2 O:B films were deposited by the co-sputtering method in a controlled oxygen/argon atmosphere. Heterojunction solar cell Cu 2 O:B/Si cell was fabricated by further optimizing the Cu 2 O:B thickness. The deposition time, introduction of the passivating layer and sputtering damage influenced the solar cell performance. A promising photo conversion efficiency (PCE) of 3.56% was obtained for the best cell with an area of 1 cm 2 within the limitations of the deposition method. The limiting factors and possibilities of pushing the efficiency limits were also discussed. In addition, the novel Cu 2 O:B material is expected to enhance the performance of other solar cells as well as various optoelectronic devices.

In chemical vapour deposition (CVD) of graphene, surface roughness and purity of the copper substrate are very crucial for obtaining uniform films. Even though electrochemical polishing is an effective technique for obtaining homogeneous graphene films, most of the experiments adopt complex experimental parameters like electrolyte heating, stirring and use of additives for better results. These are not applicable to thin copper foils used in CVD of graphene. In the present study, a simple electrochemical procedure is developed for deposition of high-quality graphene films with good coverage. The depositions of graphene films on bare and polished copper foils for the same growth conditions are analysed using various microscopic techniques. The uniformly grown graphene on copper is then directly employed as a surface-enhanced Raman scattering (SERS) substrate along with plasmonic silver nanoparticles. A simple SERS substrate having a reasonable detection limit of $$10^{-10}$$ M for R6G is achieved with uniform SERS signals over a large area. The homogeneity of SERS substrate can be attributed to the uniformity of the deposited graphene film. A simple and efficient SERS substrate using conventional methods is achieved through the incorporation of chemical vapour deposited graphene. The study covers the growth of CVD graphene film starting from substrate pre-treatment, various analyses of the film and finally the application in SERS.

Bi1.5Zn1Nb1.5O7 (BZN) and BZN-Ag composite thin films were deposited by pulsed laser ablation on Pt-Si substrate at various oxygen partial pressures. Increased oxygenation in the film due to Ag addition has resulted in the increase of lattice parameter close to that of the bulk value. Ag compositing has also resulted in the improvement of dielectric properties of BZN thin films. The C-V characteristics revealed enhanced dielectric properties for BZN-Ag composite thin films. The improvement in dielectric properties with Ag addition are associated with the increased oxygenation in the BZN thin films, formation of micro capacitors with silver particle clusters within the film as electrode and absence pinning sites for domain walls in the presence of silver.

In this paper, we report the fabrication of heterojunction carrier selective c-Si solar cell using a hole selective poly – 3,4 ethylene dioxythiophene (PEDOT:PSS) and an electron selective magnesium fluoride (MgF2) layers. Dopant- free asymmetric heterojunction solar cells (DASH cells) based on c-Si have gained considerable attention due to low-cost fabrication methods and ease of fabrication techniques. Carrier selective contact (CSC) based solar cells can reduce the interface recombination by selectively allowing only one type of carriers to pass through the selective layers. Here, solution-processed hole selective PEDOT:PSS was spin-coated on the c-Si, while the electron selective MgF2 layer was deposited by thermal evaporation technique. The conductivity of the PEDOT:PSS film was enhanced using secondary solvent doping with DMSO. The thickness of the MgF2 layer was optimized using the transmission line measurement. The dipole behavior of MgF2 would result in a decrease in the effective work function of the MgF2/metal stack. The as- fabricated solar cell showed a power conversion efficiency of 7.6% with an open-circuit voltage of 550 mV and a short circuit current of 31 mA/cm2.

Surface-enhanced Raman scattering (SERS) spectroscopy provides molecular fingerprint information with high sensitivity as low as single-molecule detection limit and offers advantages such as narrow spectral bandwidths, ability for fluorescence quenching and capacity to be used with or without optical labels. Henceforth, SERS is a good choice for cellular imaging and biosensing, detection of chemical and bioanalytes, explosives, etc. In SERS, the Raman active molecule is adsorbed to a metallic substrate in which very large electric field is generated during localized surface plasmon resonance that enhances the Raman activity of adsorbed Raman active molecule and is termed as electromagnetic enhancement mechanism (EM). The traditional SERS substrates include roughened metal electrode, metal thin film, metal nanocolloids, patterned substrates, etc. The advancements in the fabrication of efficient SERS substrate led to the development of metal oxide-based SERS substrate which is discussed in this chapter. Good stability, biocompatibility and sensitivity of semiconductors make 3D metal-semiconductor-based SERS substrates competent with traditional coinage metal-based SERS substrates. This chapter describes the development of recyclable SERS substrate using TiO2 nanorods decorated with silver nanoparticles. This helps to overcome single-use problem of traditional SERS substrates. The SERS chemical enhancement mechanism (CM), due to the chemical bond formation between molecules, also contributes to the total SERS enhancement. The surface defect-mediated chemical enhancement observed in metal oxide followed by various applications of metal oxides-based SERS substrate is also discussed in this chapter.

In this chapter, the optical properties of ZnO-based multiple quantum well (MQW) structures are discussed. Quantum wells are thin layered heterostructures grown in such a way that a smaller band gap semiconductor layer (confinement layer) having very small thickness is sandwiched between two wider band gap semiconductor layers (barrier layer). The fabrication of symmetric and asymmetric MQW structures based on ZnO with ZnMgO and CuGaO2 as the barrier layer by pulsed laser ablation technique was discussed in detail. Room-temperature PL emission was observed from these MQW structures, and a systematic blueshift in the PL peak position corresponds to the quantum confinement effect was observed with decrease in the confinement layer (ZnO) thickness. The observed room-temperature PL emission from the MQW structures is found to be blue shifted as compared to the room-temperature near-band-edge PL emission from ZnO thin film grown at same experimental conditions. This high-quality MQW structures with wide band gap semiconductor as active region can be utilized as UV emitters.

ZnO is a widely studied material owing to their wide bandgap, stability and numerous possibilities for optoelectronic applications. There are number of techniques for the fabrication of ZnO nanostructures. Most of these techniques are solution-based processes. Though there is a huge increase in surface to volume ratio for ZnO nanoparticles compared to that of bulk, the number of grain boundaries is also more. In one dimensional nanostructures, there is a significant reduction in the number of grain boundaries when compared to other nanoparticles. This chapter gives a brief overview of different growth techniques adopted for the fabrication of such one dimensional nanostructures. The ability to tune the size and shape of these nanostructures make them suitable for several electronic applications. Such applications of one-dimensional ZnO nanostructures include conventional two-terminal devices like diodes, LEDs, solar cells, etc., as well as three-terminal devices like transistors, energy generators and memory devices.

The fabrication of gas sensors has undergone a revolutionary transition from the bulk thick films to nanomaterials synthesized by various techniques. The development of high-precision gas sensors plays a crucial role in our daily life for the real-time monitoring of toxic gases in the atmosphere. Various types of gas sensors have been employed, but extensive studies were carried out on semiconducting metal oxide nanostructure-based gas sensors because of their low-cost fabrication, simple operation, high stability, response to a wide range of chemicals, etc. This chapter highlights the importance of metal oxide semiconductor nanostructures in gas sensing applications, their basic working principles, various performance parameters, factors affecting their performance, etc. The detailed gas sensing mechanism of oxide-based sensors is also discussed. Heterojunction gas sensors like p–n junction, Schottky junction, etc., can dramatically improve the sensing characteristics of oxide-based sensors. The ethanol response characteristic of p-CuO/n-ZnO junction sensor is also discussed towards the end of the chapter.

For the last four decades, researchers’ intense attentions have been received on transition-metal oxide-doped semiconductors. The substitution of transition metals on a host element adds the local magnetic moment to the system’s low-energy degree of freedom pave way for spintronics, i.e., spin electronics. So the existing semiconductors with magnetic impurities are known to be dilute magnetic semiconductors (DMSs). DMS mainly focuses on II–VI (ZnO, TiO2), IV–VI (PbTe, SnTe), and recently III–V (GaAs, InSb) semiconductors doped with transition-metal (TM) ions (Mn, Fe, Co, Ni, Cu, etc.). The realistic concerns on spintronic materials are (i) materials should retain the ferromagnetic property above room temperature and (ii) should have promising advantages over the existing technologies. It is the discovery of giant magnetoresistance (GMR) that triggered the investigations on spintronic devices. Considering the tremendous optical and magnetic properties of transition-metal oxides (TMOs), design and development of TMO-based spintronic devices are increasing day by day in comparison with non-oxide semiconductors. More importantly, ZnO claims room temperature ferromagnetism and much isolated transport properties. ZnO-based DMS materials have recently attracted much interest for its ease in band gap tuning with the addition of suitable dopants. In addition to magnetic ion doping and additional charge carriers, the ferromagnetic ordering occurs through indirect exchange interaction, RKKY interaction mediated through electrons (n-type) or holes (p-type) through the valence band of ZnO. Longer-range ferromagnetic exchange can be mediated by carriers in a spin-polarized band. ZnO-based spintronic devices can be successfully brought into fruition with the ability to create and control spin-polarized charge carrier transport. Even though a large number of researches are going on globally, achieving a higher transition temperature is still a challenging problem. Theoretical works like first principle studies give an insight to the underlying physics of these phenomena to some extent. There also lie some mismatches in predicting the oxidation states and electronic structure which could adversely affect the predicted magnetic properties when made it practical. Researchers used a self-interaction-corrected local density approximation (LDA) approach to carry out the calculations on ZnO-based DMS and presented a systematic comparison between the studies carried out within self-interaction-corrected LDA and standard LDA. The most commonly occurring experimental limitations in SQUID measurements are artifices arising from improper sample handling. The major factors to be analyzed during growth parameters include substrate effects, influence of post annealing and formation of secondary phases and effect of dopants are to be dealt with. So this chapter will give an insight of the correlation of various experimental results on ZnO-based DMS and with supporting theories and ab initio calculations.

MoS2 a member of two dimensional transition metal dichalcogenide is a potential candidate for energy storage applications due to the abundance of its elemental constituents, nontoxicity and ease of synthesized via cost effective techniques. In MoS2 the S-Mo-S trilayers are separated by weak van der Waals force and hence it can be considered as a suitable alternative to graphene. As MoS2 has better ionic conductivity than metal oxides and high theoretical capacity than graphite, it can be considered as a suitable anode material for Li –ion batteries and super capacitors. In this work MoS2 nanostructures were synthesized by simple hydrothermal technique by varying the precursor concentration maintaining a constant temperature of 200 °C for a duration of 15 hrs. As prepared samples were characterized using XRD, Raman and SEM studies. X-ray diffraction studies revealed the formation of randomly stacked layers of MoS2 in hexagonal phase. The FESEM images indicated the formation of porous spherical nanostructures of MoS2. The layered structure was further confirmed by the Raman spectra. The layered spherical structure enhances the surface area and can act as an efficient charge storage center. The electrochemical analysis suggests that hydrothermally synthesized MoS2 nanostructures has electric double layer capacitance with good cyclic stability. The increase in current density with the increase in scan rate suggest ideal super capacitive behaviour. These results confirm that MoS2 nanostructures can be used as an electrode material for energy storage applications

Epitaxial Ba0.5Sr0.5TiO3 (BST) thin films have been grown by pulsed laser deposition on (0001) Al2O3 substrate with ZnO as buffer layer. The X-ray ω-2θ, Φ-scan and reciprocal space mapping indicate epitaxial nature of BST thin films. The domain matched epitaxial growth of BST thin films over ZnO buffer layer was confirmed using Fourier-filtered HRTEM images of the film–buffer interface. The incorporation of ZnO buffer layer effectively suppressed the lattice mismatch and promoted domain matched epitaxial growth of BST thin films. Dielectric studies were conducted by fabricating coplanar interdigital capacitors on the epitaxial BST thin films. Epitaxial BST thin films show significantly improved tunable performance over polycrystalline thin films.

Owing to the low cost, nontoxicity and abundance, aluminium doped zinc oxide (AZO) thin films becomes a better alternative to transparent conducting oxides (TCO). Therefore, development of AZO films with transparent conducting properties is one of the main focuses of material scientists, and hence various methods have been attempted since the past two decades. Zinc oxide films with different Aluminium (Al) concentration are deposited on the large area (10×1Ocm) on glass substrate maintained at different substrate temperature by spray pyrolysis. Samples are characterized by XRD, UV-VIS transmittance, SEM and hall measurements. X-ray diffraction results show that films were polycrystalline in nature and the orientation changes with the increase in doping concentration. Carrier concentration, mobility and resistivity values were determined by measuring the hall measurement. The optical properties of the grown thin films were studied by taking the transmission spectra using UV-Visible spectrometer. Good correlations between structural and electrical properties were found and the influence of the substrate temperature and doping concentration on ZnO films was studied.

Thin-film transistors based on oxide and organic materials have recently attained much progress in flexible and low-cost electronic applications. The characteristic electronic properties of these materials make it a promising candidate as channel layer for the fabrication of high-performance devices. However, the p-type oxide and n-type organic TFTs are not stable because of their inherent electronic properties and the existence of a large amount of charge carrier traps. The device performance and stability of thin-film transistors are closely associated with charge transport mechanism of the active channel layer of the device. The emerging novel transistors based on amorphous oxide and organic semiconductor materials suffer from the high density of trap states inside the channel layer. The important device parameters, such as field-effect mobility and subthreshold swing depend on the charge carrier traps inside the materials. Hence, it is a scientific challenge for researchers to explore the microscopic origin of these traps. In this chapter, the density of localized states in the band gap of n-type materials such as zinc tin oxide (ZTO) and organic N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) channel layers is analysed through temperature-dependent transfer characteristics of respective thin-film transistors.

This chapter gives the reader an insight into the phenomenon of luminescence, the emission kinetics, its intrinsic and extrinsic variations, features of sensitized luminescence, and self-quenching. The merits of photoluminescence as an optical analytical tool are discussed. The industrial display scenario is laid down, with special mention on thin-film electroluminescent displays and its unique features. The shift in the research focus from sulfide-based phosphors to oxide-based light emitters is briefly outlined. Various binary and ternary oxide-based phosphor system matrices are presented in detail. The chapter concludes by highlighting the significant achievements made in related works carried at our laboratory.

Low-dimensional nanomaterials with enhanced size effect properties such as surface plasmon resonance and quantum confinements offer an unprecedented physical phenomenon, reducing devices down to atomic scale. In the last few decades, research interest in nanostructured materials has aroused due to their unusual electronic, optical, magnetic and chemical properties which are different from their bulk counterpart. In recent years, great efforts have been made on the synthesis of colloidal nanoparticles because of their promising application in various fields such as drug delivery, imaging and diagnostics. In this chapter, we discuss the synthesis of metal, semiconductor and ceramic nanoparticles by liquid phase-pulsed laser ablation (LP-PLA) technique. The optical properties of gold and silver nanoparticles grown by LP-PLA method were discussed in detail in this chapter. This chapter also discusses the growth of surfactant-free highly luminescent, transparent, chemically pure and biocompatible zinc oxide (ZnO) nanoparticles by LP-PLA. The dependence of time of ablation, laser fluence, oxygen and nitrogen bubbling during ablation on the properties of the ZnO nanoparticles was investigated. The growth of ZnO nanoparticles by varying the pH of the media gives some inference on the stability of this colloidal solution and the formation of passivation layer on the surface of these particles. The luminescent properties of the europium-doped hydroxyapatite grown by LP-PLA technique were also discussed in this chapter. These luminescent nanoparticles find immense applications in biomedical imaging and cancer detections.

Surface enhanced Raman scattering (SERS), is a widely used sensing technique in which Raman scattering by molecules is significantly enhanced by adsorbing the molecules onto corrugated metal surfaces enabling even single molecular detection. In the present work, we focus on the development of SERS substrate based on MoS2 film fabricated using pulsed laser deposition (PLD) technique taking advantage of the charge transfer interaction between MoS2 film and the probe molecule. Rhodamine 6G (R6G) is used as the probe molecule for the qualitative evaluation of SERS performance of the fabricated substrates. Additionally, silver nanoparticles (Ag NPs) are deposited on the PLD grown MoS2 film and is developed as SERS substrate. SERS performance is optimised by varying deposition time during the fabrication of MoS2 film and also by altering the concentration of Ag NPs. The enhancement depends on both the number of MoS2 layers and on the distribution of Ag NPs. Simulation based on finite difference time domain (FDTD) method is used to validate this result. Enhancement factor of the order of 105 and 108 is obtained for the monolayer MoS2 film and for the optimised MoS2 - Ag hybrid films respectively.