Porous-silicon (PS) multi-layered structures with three stacked PS layers of different porosity were prepared on silicon (Si) substrates by successively tuning the electrochemical-etching parameters in an anodization process. The three PS layers have different optical bandgap energy and construct a triple-layered PS (TLPS) structure with multiple bandgap energy. Photovoltaic devices were fabric...

Based on the first-principles calculations, we have investigated in detail the bandgap opening of silicene nanomeshes. Different to the mechanism of bandgap opening induced by the sublattice equivalence breaking, the method of degenerate perturbation through breaking the bond symmetry could split the π-like bands in the inversion symmetry preserved silicene nanomeshes, resulting into the πa1 - ...

We studied the electronic and atomic structures of anatase TiO2 codoped with Cr and N using hybrid density functional theory calculations. The nonlocal screened Hartree-Fock exchange energy is partially mixed with the traditional semilocal exchange energy. This not only patches the bandgap underestimation but also improves the description of the anion/cation-driven impurity states and the magne...

A specific structure of doped graphene with substituted silicon impurity is introduced and ab initio density-functional approach is applied for the energy band structure calculation of the proposed structure. Using the band structure calculation for different silicon sites in the host graphene, the effect of silicon concentration and unit cell geometry on the bandgap of the proposed structure i...

The aluminum oxide materials are widely used in ceramics, refractories and abrasives due to their hardness, chemical inertness, high melting point, non-volatility and resistance to oxidation and corrosion. The paper describes work done on synthesis of α-alumina by using the simple, non-expensive solution combustion method using glycine as fuel.Aluminum oxide (Al2O3) nanoparticles were synthesiz...

Layered semiconductors based on transition-metal chalcogenides usually cross from indirect bandgap in the bulk limit over to direct bandgap in the quantum (2D) limit. Such a crossover can be achieved by peeling off a multilayer sample to a single layer. For exploration of physical behavior and device applications, it is much desired to reversibly modulate such crossover in a multilayer sample. ...

In this novel work, we have studied the optical properties of CuBaM-CZFO nanocomposites. (Cu0.5Ba0.5Fe12O19)1-x/ (Co0.6Zn0.4 Fe2O4) x [where x=0.1,0.2] nanocomposites were synthesized individually by sol-gel citrate method and then made into physical mixing technique. Further characterization over their structural, morphological carried out in detail. With help UV analysis, such as, band gap en...

Solar direct, indirect and hybrid thermochemical processes are presented for the generation of hydrogen and compared to alternate solar hydrogen processes. A hybrid solar thermal/electrochemical process combines efficient photovoltaics and concentrated excess sub-bandgap heat into highly efficient elevated temperature solar electrolysis of water and generation of H2 fuel utilizing the thermodyn...

Thermoelectric materials are a promising class of direct energy conversion materials, usually consisting of highly doped semiconductors. The key to maximizing their thermal to electrical energy conversion lies in optimizing three inter-related material properties, thermal conductivity, electrical conductivity, and Seebeck coefficient. All three properties are affected by the carrier concentrati...

We investigate the influence of the energy levels on the power conversion efficiency of a P3HT:PCBM and a MEH-PPV:PV bulk heterojunction cell. We calculate the upper-limit for the efficiency, and make realistic assumptions to predict efficiencies obtainable in the near future. The ideal position of the energy levels of donor and acceptor are obtained from these calculations, giving an idea how ...