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Perovskite solar cells are a pioneering photovoltaic technology that has significantly improved performance in current years. The fundamental n-i-p planar heterojunction structure of solar cells is structured and simulated in the present work. The device configuration Glass/ITO/WS2/CH3NH3PbI3/P3HT/Au was investigated using the Solar Cell Capacitance Simulator (SCAPS-1D) program. To increase the performance of the photovoltaic solar cell thickness, bandgap, doping concentration and temperature have been varied. Further, using the optimal value of the different parameters, the performance of the photo-voltaic device such as power conversion efficiency (PCE) and Fill Factor (FF) are obtained as 27.02%, and 85.44%, respectively. Also, Open-circuit Voltage (VOC) of 1.46 V and Short-circuit current density (JSC) of 21.56 mA cm−2 were achieved. The influence of donor concentrations has been studied by varying its value from 1 × 10−12 cm−3 to 1 × 10−20 cm−3 for the proposed device. Thus, using different charge transport materials, the power convergence efficiency of the perovskite solar cell has been enhanced. Our simulation study reveals that the proposed configuration could be used to fabricate a device for the improvement of the efficient perovskite solar cell.

Large-quantity synthesis of single-crystalline perfectly hexagonal-shaped ZnO rods has been achieved through the thermal evaporation of metallic zinc powder in the presence of oxygen without the use of metal catalyst or additives. Detailed structural analyses confirm that the structures formed exhibit a wurtzite hexagonal phase and are preferentially oriented along the c-axis direction. Low-temperature photoluminescence shows that the exciton emission bound-to-neutral donor (D0X) and free-exciton dominate the edge emission region while the donor–acceptor pair (DAP) and its replica dominate the lower energy regions. With increased temperature, D0X decreases abruptly and is then suppressed, but with further increase in temperature (>100 K) the photoluminescence spectra are dominated by the DAP.

The growth of perfectly hexagonal-shaped ZnO nanorods, with Zn-terminated (0001) facets bounded with [Formula: see text] surfaces, has been performed on nickel-coated Si(100) substrate via thermal evaporation using metallic zinc powder and oxygen. Detailed structural investigations confirmed that the synthesized nanorods are single crystalline with the wurtzite hexagonal phase and preferentially grow along the c-axis direction. Raman spectra of the as-grown ZnO nanorods showed an optical-phonon E(2) mode at 438 cm(-1), indicating that as-grown nanostructures are in good crystallinity with the wurtzite hexagonal phase. The ZnO nanorods were found to show strong band edge emission with very weak or no deep-level emission, as shown by photoluminescence measurements. The clear observation of free excitons at low temperatures (13-50 K) indicates that the as-grown ZnO nanorods are of high quality.

Two-dimensional ZnO nanosheet networks composed of many thin and uniform hexagonal-shaped ZnO nanosheets and ZnO nanodiscs were prepared in a large scale on silicon substrate through thermal evaporation using ZnCl2 and O2 as source materials for Zn and oxygen, respectively, without the use of metal catalysts or additives. Detailed structural studies indicated that the synthesized products are single crystalline with wurtzite hexagonal structure. Raman scattering of the synthesized products confirmed that the as-grown structures have good crystal quality with a hexagonal wurtzite phase. Room temperature photoluminescence spectra showed a strong green band with a suppressed UV emission from the ZnO nanosheet networks, but on the other hand a dominant and strong near band edge emission with a much suppressed deep level emission was observed in the nanodiscs. The growth mechanism of these structures is also discussed in detail.

We study heavy-ion fusion reactions at energies near the Coulomb barrier, in particular with neutron-rich radioactive ion beams. Dynamic microscopic calculations are carried out on a three-dimensional lattice using the Density-Constrained Time-Dependent Hartree-Fock (DC-TDHF) method. New results are presented for the $^{132}$Sn+$^{40}$Ca system which are compared to $^{132}$Sn+$^{48}$Ca studied earlier. Our theoretical fusion cross-sections agree surprisingly well with recent data measured at HRIBF. We also study the near- and sub-barrier fusion of $^{24,16}$O on $^{12}$C which is important to determine the composition and heating of the crust of accreting neutron stars., Comment: Talk given by . Volker E. Oberacker at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS)

We present the numerical details of a new method for calculating ion-ion interaction potentials from time-dependent Hartree-Fock calculations using density as a constraint.

Layered hexagonal discs of CuO were synthesized on a large scale via low-temperature hydrothermal growth process at 130 °C using copper nitrate, hexamethylenediamine and NH4OH. The detailed morphological investigations by field emission scanning electron microscopy and transmission electron microscopy (TEM) clearly revealed that the synthesized CuO structures are made by the well layer-by-layer accumulation of several sheets which arranged themselves in such a special manner that they exhibit the hexagonal discs of CuO. The detailed structural characterizations of the hexagonal CuO discs were done by high-resolution TEM and x-ray diffraction which confirmed that the synthesized structures possessing well nanocrystalline nature and monoclinic structure. The purity and composition of the synthesized products were examined using energy dispersive spectroscopy, elemental mapping and Fourier transform infrared spectroscopy. Using UV–Vis spectroscopy at room temperature we obtained indirect and direct band gap values slightly blue shifted to the bulk values. Finally, a plausible growth mechanism has been proposed for the formation of CuO layered hexagonal discs.

Optical and field emission (FE) properties of aligned single-crystalline ZnO nanorods, grown on aluminium substrate at 530 °C by the non-catalytic thermal evaporation process, have been examined. Raman-scattering and room-temperature PL spectra exhibit a strong and sharp optical phonon E2 mode at 437 cm−1 and a strong ultraviolet emission at 381 nm, respectively. The FE characterization shows that a turn-on field for the vertically aligned nanorods was 5.8 V µm−1 and the emission current density reached to 0.061 mA cm−2 at an applied electrical field of 9.0 V µm−1 and shows no saturation. The field enhancement factor β was estimated, from the F–N plot, to be about ~2.081 × 103.

Well-crystallized ZnO nanowires were grown in large quantity on aluminium foil, by a non-catalytic thermal evaporation method using metallic zinc powder in the presence of oxygen at low temperature. Detailed structural and optical characterizations confirmed that the as-grown nanowires were highly crystalline, possessed a wurtzite hexagonal phase, had grown along the c-axis direction and exhibited excellent optical properties. The electrical characteristics of an individual nanowire were observed in air and vacuum by fabricating field-effect transistor (FET) devices. The transistors turned on typically between −5 and 0 V in ambient air. However, a large threshold voltage (Vth) shift, ~5 V, towards negative gate bias was observed in high vacuum. The shift of Vth is believed to be related to the charge transfer from the ZnO nanowire surface to the physically adsorbed OH or oxygen. Moreover, the fabricated FETs show a high conductivity ON/OFF ratio of about ~102 with ultraviolet (UV) light and hence provide an effective way to use these devices in nanoscale UV detectors and optoelectronic switches.

Well-aligned ZnO nanorod and nanopencil arrays were synthesized in a high density on ZnO/Si substrate by a low-temperature aqueous solution technique. Detailed structural characterizations revealed that the as-synthesized nanorods and nanopencils were single crystalline, with a hexagonal phase, and with growth along the [0001] direction. The room-temperature photoluminescence spectra showed a strong ultraviolet emission at 381 nm, a weak blue band at 460 nm, and a broad green emission at 580 nm. A detailed growth mechanism has been proposed for the formation of nanorods and nanopencils based on the different crystallographic habits of wurtzite hexagonal ZnO.