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Inverted bulk heterojunction organic solar cells having device structure ITO/ZnO/poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) /MoO3/Ag were fabricated with high photoelectric conversion efficiency and stability. Three types of devices were developed with varying electron transporting layer (ETL) ZnO architecture. The ETL in the first type was a sol-gel-derived particulate film of ZnO, which in the second and third type contained additional ZnO nanowires of varying concentrations. The length of the ZnO nanowires, which were developed by the electrospinning technique, extended up to the bulk of the photoactive layer in the device. The devices those employed a higher loading of ZnO nanowires showed 20% higher photoelectric conversion efficiency (PCE), which mainly resulted from an enhancement in its fill factor (FF). Charge transport characteristic of the device were studied by transient photovoltage decay and charge extraction by linearly increasing voltage techniques. Results show that higher PCE and FF in the devices employed ZnO nanowire plantations resulted from improved charge collection efficiency and reduced recombination rate. Refereed/Peer-reviewed

We report the extraordinary lithium storage performance of porous LiMn2O4 hollow nanofibers synthesized by electrospinning technique. The electrospun LiMn2O4 hollow nanofibers retained 87% of initial reversible capacity after 1250 cycles at the 1 C rate. Further, excellent cycling profiles at 55 °C and cubic spinel to tetragonal phase transformation are also noted.

We report a facile and simple means of synthesizing a macroscopic array of ZnO nanorods with high feature densities using a modified hydrothermal approach that involves the in situ introduction of polyelectrolyte. The ZnO nanorod arrays with heights of 1.5 μm and diameters of 350 nm were consistently reproducible and were bestowed with the advantage of in situ process tunability offered by employing polyethylenimine (PEI) as a surface modifying agent. The fabrication combines benefits from the hydrothermal approach in terms of process simplicity and flexibility and from the use polyelectrolyte that offers a better nanorod surface, quenched defect levels and enhancement of the UV band edge emission. Structural and elemental analysis of the PEI-modified and unmodified nanorods emphasize the fact that the intentional introduction of PEI results in a nanorod with better surface quality as evidenced by photoluminescence (PL) spectra. The tunability of the feature dimensions of the nanorods and an analysis of the bulk and surface (surface defect) responses to the PL point to significant promise of high density orthogonal nanorods in a number of optoelectronic applications. While the defects in the ZnO nanorods can point towards the application of ZnO nanorods in charge trap flash memory devices, highly crystalline, size tunable, high aspect ratio nanorods find applications as building components in solid state lighting.

In this work, we demonstrate a simple method of synthesizing nanoscale polythiophene-gold nanoparticle (AuNP) hybrid systems assembled by the Langmuir-Blodgett (LB) method. Regio-regular poly(3-(2-methoxyethoxy)ethoxymethyl)thiophene-2,5-diyl (PMEEMT) and poly(3-dodecylthiophene) (PDDT) were employed as the polymeric constituents. The presence of PDDT improved the amphiphilicity of PMEEMT by addressing the phase separation that occurred due to convective hydrodynamic instability on the substrate. 4 layer stacks of 90% and 99% PMEEMT films exhibited uniform film structure with a significant reduction in phase separation. A detailed mechanism for minimization of the surface effect has been proposed based on the interaction of polythiophenes with the substrate. For the first time, an ex situ approach has been adopted to incorporate AuNPs into LB films without affecting the film morphology and uniformity. The incorporation of AuNPs into the polythiophene matrix, aided by the affinity of sulphur for gold, was strongly dependent on the molecular arrangement of the matrix, which in turn depended on the composition of the matrix. The hybrid polythiophene films exhibited enhanced conductivity and can be applied in sensors, photovoltaics and memory devices.

Clay minerals can act as a uniform dispersion medium for nano-sized carbon particles. However, literature on the preparation and characteristics of palygorskite-carbon nanocomposites is scant. Using a hydrothermal carbonisation technique this study developed two nanocomposites on fibrous palygorskite from starch: the first without a post-synthesis treatment (Composite 1); and the second with an activation at 550°C for 3h (ramp at 10°Cmin-1) under CO2 environment (200mLmin-1) (Composite 2). A uniform dispersion of nano-scale carbon spheres was formed on partially destroyed palygorskite structures. Composite 2, which indicated the formation of graphitised carbon nanoparticles, generated a 17-fold greater specific surface area than Composite 1 and also created micro- and mesopores in its structure. The nanocomposites, especially in Composite 1, contained organic surface functional groups (CH, CC, CO) and indicated variable affinity to cationic and anionic dye compounds. While Composite 2 adsorbed a larger amount of anionic orange II dye (23mgg-1), Composite 1 adsorbed more cationic methylene blue (46.3mgg-1). Isothermal and kinetic modelling of the adsorption data indicated that in addition to electrostatic attraction for methylene blue adsorption on both nanocomposites, a pore diffusion mechanism was involved and the boundary resistance was greater for orange II than methylene blue adsorption. Being a material developed from green biomass (starch) and an abundant natural resource (palygorskite), these nanocomposites have immense potential for application in environmental remediation including in situ immobilisation of contaminants in soil. Refereed/Peer-reviewed