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Polyaniline nanorod-graphene nanoflake hybrid films are excellent broadband EMI shields. The extent of absorption can be effectively tuned by adjusting the concentration of graphene in the polyaniline matrix.

High-pure, rhombohedral lanthanum manganite was prepared by a facile sol–gel method at different annealing temperatures. The sample prepared at 700 °C shows the best electrochemical performance suitable for supercapacitor applications.

Organic–inorganic metal halide perovskites (OIMHPs) are proving to be disruptive for the conventional silicon solar cell technology with conversion efficiencies breaching 29% using OIMHPs based hybrid structures. Synthesis of the colloidal Methyl-ammonium lead bromide (CH3NH3PbBr3) quantum dots was done using Ligand-Assisted re-precipitation strategy. Subsequently CH3NH3PbBr3 thin films were grown using these quantum-confined nano-particles by means of a simple solvent evaporation-induced self-assembly technique. Structural analyses of the colloidal nano-particles and thin films were done using High-Resolution Transmission Electron Microscopy (HR-TEM), X-ray diffraction and Raman spectroscopy. The crystal symmetry could be assigned to the Pnma space group with a = 7.94 A, b = 11.55 A and c = 8.15 A. Different to the green photoluminescence exhibited by bulk CH3NH3PbBr3, the thin films grown by us exhibit intense blue photoluminescence at a wavelength of ~ 488 nm with lower intensity emissions at ~ 463 nm and ~ 429 nm at room temperature. The uniqueness in blue emission from CH3NH3PbBr3 thin films grown by us is modeled based on the presence of excitons in this system.

We present a simple and facile method to synthesize nanoplatelets of 2D Ruddlesden-Popper (RP) perovskites of the type (CH3(CH2)3NH3)2(CH3NH3)Pb2I7 where n = 2. The 2D RP nanoplatelets are synthesized from bulk 2D RP crystals via a reflux pre-treatment mediated-ultrasonication method. The as-synthesized 2D RP nanoplatelets are highly air-stable even after two months of storage under an ambient atmosphere. The bulk 2D RP crystals and 2D RP nanoplatelets are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Kelvin probe force microscopy, UV-visible spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence, time correlated single photon counting measurement, etc. A significant blue shift in the ultraviolet-visible absorption spectrum, high photoluminescence in the UV region, and the modified work function of the nanoplatelets indicate a strong quantum confinement effect. The quantum confinement in the nanoplatelets is further confirmed using XPS. A photodetector fabricated using these 2D RP nanoplatelets exhibits a high photodetectivity of 3.09 × 1010 Jones.

We have used ligand-assisted re-precipitation (LARP) technique to grow colloidal nano-platelets of Cu-doped cesium lead bromide (CsPbBr3) perovskite in room ambient. Using selected-area diffraction and transmission electron microscopy, the structure of the nano-crystals was identified to be the orthorhombic crystal phase. From green emission (520 nm) for the un-doped CsPbBr3 nano-crystals, we were able to shift the emission to blue (464 nm) for the 1% doped CsPbBr3 nano-platelets. As the doping concentration was increased, the edge length of nano-platelets increased and resulted in a decrease in the Stokes shift. Optical band gap was found to increase from 2.6 eV for the un-doped CsPbBr3 to 2.81 eV for the 2% doped sample. We report that the formation of excitons with binding energy in the regime 70–110 meV is responsible for the blue photoluminescence. The green emissions have been identified to be due to defect levels located at 210–380 meV below the conduction band edge. The PLE peaks exhibit no shift with increasing excitation wavelength signifying quantum confinement effect. The substitution of lead with copper provides an opportunity in making lead-free perovskite solar cells in the near future.

Although quantum dots (QDs) based on two dimensional (2D) materials have manifested fascinating properties and promising applications in a wide range of fields, a low cost and non-tedious approach for the preparation of atomically thick 2D QDs with high yield remains elusive. Herein, for the first time, we demonstrate a reflux pretreatment-mediated sonication approach to produce a series of ultrathin 2D QDs (e.g., graphene, TiS2, MoS2, MoSe2, WSe2, NbS2, SnS2, and h-BN QDs) from their bulk counterparts. The solvent molecules, confined in the channels of layered materials during reflux, assist the delamination and fracture of 2D sheets in the process of bath sonication. The resulting 2D QDs exhibited uniform lateral size distribution of 2–7 nm and a mean thickness of 0.8–1 nm, almost identical to the monolayer thickness of layered materials. To demonstrate the unique property of these 2D QDs, the optical limiting activity was studied using open aperture z-scan technique. TiS2 QDs exhibited appreciable nonlinear optical limiting, reaching 50% by a tapered and sharp absorption at input laser fluence of 4.24 GW/cm2.

The present work is focused on the impressive electromagnetic shielding effectiveness of doped polyaniline films in the C and X bands of the electromagnetic spectrum. The observed value of shielding effectiveness of about 37dB is found to depend on the electrical conductivity and crystallinity of the films. The films synthesised by self-stabilised dispersion polymerisation are found to be crystalline with appreciable electrical conductivity as evident from the structural and morphological characterizations. The interesting feature is that most of the literature available on the shielding effectiveness of polyaniline is restricted to thicker films. The values reported here for the C and X bands comply with the commercial standards and are quite appreciable for micrometre thick films

Lithium-ion batteries (LIBs) have attracted the energy storage industry due to their high capacity, easy processability, and long cycle life. The recent developments in the acceptance of electric vehicles, in response to carbon dioxide pollution, is anticipated to accelerate the growth of LIB demand. Petroleum fuel-based vehicles are disappearing from the roads globally, due to the influence of green-energy technologies, ranging from hybrid electric vehicles to electric vehicles. Nowadays, due to the rapid growth of wearable electronic devices, there is a massive demand for flexible and wearable energy storage to supply power to these devices. Polymers are extensively used for developing solid-state electrolytes for LIBs. The overall performance of the battery suffers a setback due to the narrow electrochemical windows, poor ionic conductivities, and low mechanical strength of these polymer electrolytes. Ceramic fillers are generally divided into two categories, inactive and active fillers.

A significant improvement in the performance of lithium (Li)-ion batteries (LIBs) can be achieved by designing the active anodes made of carbon-based materials. The constraints in achieving high reversible capacity, low coulombic efficiency, high voltage hysteresis, and rate capability restrict their application in hybrid electric vehicles and the futuristic all-electric vehicles. The development of low-cost materials and their successful implementation are also among the major concerns. This has motivated the battery community to think about inexpensive transition metal oxides-based anodes for LIBs. Among the metal-oxides family, manganese oxides (MnOx) have drawn immense interest due to their low-cost, high reversible capacity, improved cycling performance, and high rate capability even at high current rates. The advancements in the field of nanoscience and technology have envisaged the utilization of various MnOx nanostructures for effective intercalation/de-intercalation of Li-ions and to provide short diffusion lengths for electron and Li-ion transport. Among these, highly conducting anodes made of electrospun MnOx-based composites are potential substitutes for conventional LIB anode materials as they can considerably improve the capacity, coulombic efficiency, and rate capability. Electrospinning is a viable method to prepare pristine MnOx nanostructures as well as their composites for application as anodes in LIBs. A typical preparation procedure includes dispersing the precursors of MnOx in a polymer precursor (e.g., polyacrylonitrile, polymethylmethacrylate, etc.) followed by electrospinning and a further heat-treatment at the desired temperature that determines the formation of pristine MnOx nanostructures or MnOx-based composites. This chapter focuses on the recent advancements in the field of electrospun MnOx-based composite anodes for the next generation LIBs. The preparation and performance evaluation of electrospun MnOx-based composite anodes are explained in detail. A future perspective of electrospun MnOx-based composite anodes for the development of flexible LIBs is also included.