For the last decade, researchers have attempted to construct photovoltaic (PV) devices using a mixture of inorganic nanoparticles and conjugated polymers. The goal is to construct layers that use the best properties of each material e.g., flexibility from the polymer and high charge mobility from the nanoparticles or blue absorbance from the polymer complementing red absorbance from the nanoparticles. This critical review discusses the main obstacles to efficient hybrid organic/inorganic PV device design in terms of contributions to the external and internal quantum efficiencies. We discuss in particular the role that ligands on the nanoparticles play for mutual solubility and electronic processes at the nanoscale. After a decade of work to control the separation distance between unlike domains and the connectivity between like domains at the nanoscale, hybrid PV device layers are gaining in efficiency, but the goal of using the best properties of two mixed materials is still elusive. IntroductionThere is a serious concern that the global temperature will increase by 1 to 6 C and the CO 2 concentration will exceed the range from 570 to 970 parts per million during the 21 st century. 1 These numbers create tremendous awareness towards the increasing need for renewable energy resources. Approximately 80% of the world energy supply still comes from fossil fuels. 2 Unfortunately, photovoltaic (PV) energy only contributes 0.04% of the total energy production, 3 although the earth receives enough energy in an hour to fulfil the yearly demand. The main reason for low penetration of PV into the energy market is the high cost of providing power from PV. We review here hybrid organic/inorganic PV devices that, due to ease of fabrication, have the chance to greatly reduce the cost of PV energy.The current PV industry is dominated by silicon-based photovoltaics. There are other types of PVs such as single and multi-junction thin films that have also captured a significant part of the PV market because of their high power conversion
By use of a flow cell in conjunction with surface plasmon resonance, experimental results are obtained for the intrinsic kinetics of sodium dodecyl sulfate (SDS) adsorption on and desorption from self-assembled monolayers (SAMs) on gold. When the flow of the bulk surfactant solution in the flow cell is increased, conditions are reached where the surface kinetics are rate controlling and mass transfer limitations in the bulk solution are negligible. The SDS adsorption and desorption rates increase with the bulk surfactant concentration in the monomer regime. At and above the critical micelle concentration of SDS, the adsorption and desorption rates become nearly constant. It is shown that SDS needs to be recrystallized to remove minute impurities. The results suggest that the SDS monomers play a dominant role in adsorption and desorption on SAMs. Sodium dodecyl sulfate has a greater affinity for hydrophobic SAMs than for charged, hydrophilic SAMs. The data also suggest that the kinetics of adsorption and surface micelle formation for hemicylinders is a slower process than that for adsorption and formation of hemispheres.
Solar energy can provide an abundant source of renewable energy (electrical and thermal). However, because of its unsteady nature, the storage of solar energy will become critical when a significant portion of the total energy will be provided by solar energy. In this paper, current solar energy storage technologies are reviewed. Storage methods can be classified into categories according to capacity and discharge time. New developments in solar energy storage require advances in chemical engineering and materials science. Life cycle assessment (LCA) is an important tool to evaluate energy consumption and environmental impact of renewable energy processes. LCAs of some of the storage methods are reviewed. It is important to note that, while using renewable energy sources such as solar power, storage methods based on nonrecyclable materials or methods that consume significant amounts of energy may undermine the effort to reduce energy consumption.
We report a novel route for fabricating Au-Te nanocables. Using nanoporous polycarbonate tract-etching (PCTE) membrane as the template, Au nanotubes were fabricated by electroless Au deposition inside the nanopores of the PCTE membrane. Using the Au nanotube membrane as a second template, Te was deposited on the surfaces of the Au nanotubes by slow electrochemical deposition, taking advantage of underpotential deposition (UPD). The deposition rate was sufficiently slow to radially grow Te nanotubes coaxially within the Au nanotubes to form nanocables.
Successive layer properties and peptide insertion in an assembly of supported mobile phospholipid bilayers on polyion/alkylthiol layer pairs were investigated in a combined optical, electrochemical, and surface topography study using surface plasmon resonance (SPR), cyclic voltammetry (CV), and atomic force microscopy (AFM). The use of a long-chain alkylthiol in this assembly was too insulating, and thus, a short-chain alkylthiol was used to probe membrane electrochemical properties. Using AFM, we found that the insulating properties of long-chain and short-chain alkylthiol layers are associated with a continuous layer and domain formation, respectively. Increased insulating properties of the supported bilayers were observed when mixtures of negatively charged and zwitterionic/neutral lipids were used. By attempting to obtain high-resolution images and make depressions in the surface using AFM, we found that this bilayer was more mobile than a bilayer composed completely of negatively charged lipid. A pore-forming antimicrobial and antiviral peptide from porcine leukocytes, protegrin-1, increased the charge transfer through the supported biomembranes. The peptide's influence on the electrochemical and topological properties of the membrane depended on the lipid compositions, although comparable amounts of the peptide were associated with the various membranes. The multilayer surface morphology is quantitatively characterized by using roughness measurements for a large set of data involving root-mean-square roughness (RMS) and power spectra density analysis (PSD). The RMS values obtained for each deposited layer reveal that the surface roughness is characterized in the nanometer and subnanometer range. Surface roughness decreased with each deposited layer in the supported bilayer system but increased with peptide adsorption to the lipid bilayer. A decreased degree of association between the lipid membrane and a mutant protegrin further demonstrates the model membrane as a sensitive tool for studying the mechanisms of antimicrobial peptides.
Nanoscale structures have been at the core of research efforts dealing with integration of nanotechnology into novel electronic devices for the last decade. Because the size of nanomaterials is of the same order of magnitude as biomolecules, these materials are valuable tools for nanoscale manipulation in a broad range of neurobiological systems. For instance, the unique electrical and optical properties of nanowires, nanotubes, and nanocables with vertical orientation, assembled in nanoscale arrays, have been used in many device applications such as sensors that hold the potential to augment brain functions. However, the challenge in creating nanowires/nanotubes or nanocables array-based sensors lies in making individual electrical connections fitting both the features of the brain and of the nanostructures. This review discusses two of the most important applications of nanostructures in neuroscience. First, the current approaches to create nanowires and nanocable structures are reviewed to critically evaluate their potential for developing unique nanostructure based sensors to improve recording and device performance to reduce noise and the detrimental effect of the interface on the tissue. Second, the implementation of nanomaterials in neurobiological and medical applications will be considered from the brain augmentation perspective. Novel applications for diagnosis and treatment of brain diseases such as multiple sclerosis, meningitis, stroke, epilepsy, Alzheimer's disease, schizophrenia, and autism will be considered. Because the blood brain barrier (BBB) has a defensive mechanism in preventing nanomaterials arrival to the brain, various strategies to help them to pass through the BBB will be discussed. Finally, the implementation of nanomaterials in neurobiological applications is addressed from the brain repair/augmentation perspective. These nanostructures at the interface between nanotechnology and neuroscience will play a pivotal role not only in addressing the multitude of brain disorders but also to repair or augment brain functions.
Surface chemistry of the capacity fading of the Li x Mn2O4 cathode was investigated using atomic force microscopy (AFM), energy-dispersive X-ray analysis (EDAX), and X-ray photoelectron spectroscopy (XPS). Measurements show a decrease in the cathode capacity from 124 mA h g-1 before storage to 102 mA h g-1 after storage in an electrolyte of 1 M LiPF6/EC + DMC + DEC at 70 °C for 5 days. Surface morphological changes of the Li x Mn2O4 cathode were monitored using contact and tapping AFM and lateral force microscopy in air. Nanoscale changes of the charged cathode before and after storage at 70 °C were observed. Before storage, homogeneous grains of approximately 100−200 nm are seen. After storage, fine and nearly round shaped structures of 10−30 nm in size are observed covering the larger grains on the surface of the cathode. This change in morphology suggests film deposition on the cathode's surface, which increases the resistance for Li+ ion transport in and out of the cathode. Results from EDAX show that compounds containing phosphorus and fluorine are also deposited on the surface of the cathode. Surface analysis of the cathode with XPS suggests the presence of MnF2. The conversion of the oxidation state of manganese on the surface of the cathode from MnO2 to MnO during storage at the elevated temperature was observed with XPS.
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