Switching of ferroelectric liquid crystal doped with cetyltrimethylammonium bromide-assisted CdS nanostructures

Large scale high yield cadmium sulfide (CdS) nanowires with uniform diameter were synthesized using a rapid and simple solvo-chemical and hydrothermal route assisted by the surfactant cetyltrimethylammonium bromide (CTAB). Unique CdS nanowires of different morphologies could be selectively produced by only varying the concentration of CTAB in the reaction system with cadmium acetate, sulfur powder and ethylenediamine. We obtained CdS nanowires with diameters of 64–65 nm and lengths of up to several micrometers. A comparative study of the optical properties of ferroelectric liquid crystal (FLC) Felix-017/100 doped with 1% of CdS nanowires was performed. Response times of the order of from 160 to 180 μs, rotational viscosities of the order of from 5000 to 3000 mN s m−2 and polarizations of the order of from 10 to 70 nC cm−2 were measured. We also observed an anti-ferroelectric to ferroelectric transition for CdS doped FLC instead of the ferroelectric to paraelectric transition for pure FLC.

Synthetic strategy of porous ZnO and CdS nanostructures doped ferroelectric liquid crystal and its optical behavior

A simple and scalable chemical approach has been proposed for the generation of 1-dimensional nanostructures of two most important inorganic materials such as zinc oxide and cadmium sulfide. By controlling the growth habit of the nanostructures with manipulated reaction conditions, the diameter and uniformity of the nanowires/nanorods were tailored. We studied extensively optical behavior and structural growth of CdS NWs and ZnO NRs doped ferroelectric liquid crystal Felix-017/100. Due to doping band gap has been changed and several blue shifts occurred in photoluminescence spectra because of nanoconfinement effect and mobility of charges.

Aluminum slurry coatings to replace cadmium for aeronautic applications

Cadmium has been widely used as a coating to provide protection against galvanic corrosion for steels and for its natural lubricity on threaded applications. However, it is a toxic metal and a known carcinogenic agent, which is plated from an aqueous bath containing cyanide salts. For these reasons, the use of cadmium has been banned in Europe for most industrial applications. However, the aerospace industry is still exempt due to the stringent technical and safety requirements associated with aeronautical applications, as an acceptable replacement is yet to be found. Al slurry coatings have been developed as an alternative to replace cadmium coatings. The coatings were deposited on AISI 4340 steel and have been characterized by optical and electron microscopy. Testing included salt fog corrosion exposure, fluid corrosion exposure (immersion), humidity resistance, coating-substrate and paint-coating adhesion, electric conductivity, galvanic corrosion, embrittlement and fatigue. The results indicated that Al slurry coatings are an excellent alternative for Cd replacement.

Ionization levels of doped copper indium sulfide chalcopyrites

The electronic structure of modified chalcopyrite CuInS2 has been analyzed from first principles within the density functional theory. The host chalcopyrite has been modified by introducing atomic impurities M at substitutional sites in the lattice host with M = C, Si, Ge, Sn, Ti, V, Cr, Fe, Co, Ni, Rh, and Ir. Both substitutions M for In and M for Cu have been analyzed. The gap and ionization energies are obtained as a function of the M-S displacements. It is interesting for both spintronic and optoelectronic applications because it can provide significant information with respect to the pressure effect and the nonradiative recombination.

Electronic, structural, and optical properties of the host and Cr-doped cadmium thioindate

The cadmium thioindate spinel CdIn2S4 semiconductor has potential applications for optoelectronic devices. We present a theoretical study of the structural and optoelectronic properties of the host and of the Cr-doped ternary spinel. For the host spinel, we analyze the direct or indirect character of the energy bandgap, the change of the energy bandgap with the anion displacement parameter and with the site cation distribution, and the optical properties. The main effect of the Cr doping is the creation of an intermediate band within the energy bandgap. The character and the occupation of this band are analyzed for two substitutions: Cr by In and Cr by Cd. This band permits more channels for the photon absorption. The optical properties are obtained and analyzed. The absorption coefficients are decomposed into contributions from the different absorption channels and from the inter-and intra-atomic components.

Photovoltaic application of the V, Cr and Mn-doped cadmium thioindate

The CdIn2S4 spinel semiconductor is a potential photovoltaic material due to its energy band gap and absorption properties. These optoelectronic properties can be potentiality improved by the insertion of intermediate states into the energy bandgap. We explore this possibility using M = Cr, V and Mn as an impurity. We analyze with first-principles almost all substitutions of the host atoms by M at the octahedral and tetrahedral sites in the normal and inverse spinel structures. In almost all cases, the impurities introduce deeper bands into the host energy bandgap. Depending on the site substitution, these bands are full, empty or partially-full. It increases the number of possible inter-band transitions and the possible applications in optoelectronic devices. The contribution of the impurity states to these bands and the substitutional energies indicate that these impurities are energetically favorable for some sites in the host spinel. The absorption coefficients in the independent-particle approximation show that these deeper bands open additional photon absorption channels. It could therefore increase the solar-light absorption with respect to the host.

Inorganic Photovoltaics - Planar and Nanostructured Devices

Since its invention in the 1950s, semiconductor solar cell technology has evolved in great leaps and bounds. Solar power is now being considered as a serious leading contender for replacing fossil fuel based power generation. This article reviews the evolution and current state, and potential areas of near future research focus, of leading inorganic materials based solar cells, including bulk crystalline, amorphous thin-films, and nanomaterials based solar cells. Bulk crystalline silicon solar cells continue to dominate the solar power market, and continued efforts at device fabrication improvements, and device topology advancements are discussed. III-V compound semiconductor materials on c-Si for solar power generation are also reviewed. Developments in thin-film based solar cells are reviewed, with a focus on amorphous silicon, copper zinc tin sulfide, cadmium telluride, as well as nanostructured Cadmium telluride. Recent developments in the use of nano-materials for solar power generation, including silicon and gallium arsenide nanowires, are also reviewed.