Photovoltaics literature survey (No. 90)

In order to help keep readers up‐to‐date in the field each issue of Progress in Photovoltaics will contain a list of recently published journal articles most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Transactions on Electron Devices, Journal of Applied Physics, Applied Physics Letters, Progress in Photovoltaics, and Solar Energy Materials and Solar Cells. To assist the reader, the list is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions please email Santosh Shrestha at s.shrestha@unsw.edu.au . Copyright © 2011 John Wiley & Sons, Ltd.     

Study of Zinc Oxide nano/micro rods grown on ITO and glass substrates

Highly oriented multilinked ZnO nano and micro rods were deposited using aqueous solution growth technique on ITO and glass substrates. Their study provides a basic understanding of effect of the base material on the growth of nanorods. An equimolar aqueous solution of Zinc nitrate and hexamine (HMT) was used for the preparation of ZnO nanorods arrays. ZnO was deposited on ITO and glass substrates after establishing the optimal pH and concentration, which yield the best substrate coverage for precursor solution. To achieve uniform growth and high density of ZnO nanorods, the prepared solution was heated at certain constant temperature. The experimental results have been obtained by using Scanning Electron Microscope (SEM), X-ray diffractometer (XRD) and Fluorescence Spectroscope which shows highly oriented nanorods perpendicular to the surface of substrates and a comparative study of ITO and glass grown nanorod arrays shows that the structural chemistry of the substrate clearly affects the growth nanostructures. The high variation in optical properties can be attributed by the heating temperatures and limited presence of reactants available for the controlled growth on substrates. It is also observed confined and decreased particle size with enhanced nucleation on ITO substrate as compared to glass. Due to the physical limitations in the growth, this kinetically controlled nucleation would be responsible for producing the highly uniform, dense and perpendicularly oriented nanorods.     

First principle investigation into structural growth and magnetic properties in GenCr clusters for n=1–13

The ground state structures and their magnetic properties have been investigated for Ge_nCr clusters (1≤n≤13)$(1\le n\le 13)$ using spin polarized density functional theory. The growth behavior of Ge_nCr clusters for n≤13$n\le 13$ shows preference of Cr atom to stabilize at the exohedral position. The binding energy increases with the increase in cluster size, but shows a small decrease w.r.t. pure Ge_n clusters. Interestingly, the magnetic moment in Cr doped Ge_n is found to be either 4_μB$4{\mathrm{\mu }}_{\mathrm{B}}$ or 6_μB$6{\mathrm{\mu }}_{\mathrm{B}}$ and shows no sign of magnetic quenching in any of the ground state structures and isomers investigated up to n  =13. It is found that the magnetic moment is mainly localized at the Cr atom along with small induced magnetic moment on surrounding Ge atoms. The results are consistent with the available theoretical results for n≤5$n\le 5$.     

Topographically controlled growth of silver nanoparticle clusters

We present a straightforward method to form regular arrays of chemically synthesized Ag nanoparticle clusters, which are preferentially nucleated and developed inside pre‐patterned Si nanowells. The sizes and shapes of the clusters follow the dimensions of the lithographically defined Si nanowells, which here have a depth of 100 nm and form a square array with a pitch of 300 nm. Potential use of the array of Ag nanoparticle clusters as a surface‐enhanced Raman scattering (SERS) based sensing platform is demonstrated by the calculation of locally enhanced electromagnetic fields and by confocal microscopic measurements of increased Raman signals from organic molecules adsorbed on the Ag nanoparticle clusters. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparative study of the three different fluorophore antibody conjugation strategies

The progression in bioconjugational chemistry has significantly contributed to the evolution and success of protein biology. Mainly, antibody chemistry has been a subject of intensive study owing to the expansion of research areas warranted by using various derivatives of conjugated antibodies. Three reactive moieties (amine, sulfhydryl and carbohydrate) in the antibodies are chiefly favored for the conjugational purpose. This feature is known for decades, nevertheless, amine based conjugation is still the most preferred strategy despite the appreciation the other two methods receive in conserving the antigen binding affinity (ABA). No single report has been published, according to our knowledge, where these three conjugation strategies were applied to the same fluorophore antibody systems. In this study, we evaluated conjugation yield, time demand and cost efficiency of these conjugation procedures. Our results showed that amine based conjugations was by far the best technique due to its simplicity, rapidity, ease of operation, higher conjugate yield, cheaper cost and potential for larger fluorophore/protein labeling ratio without having much effect in ABA. Furthermore, sulfhydryl labeling clearly excelled in terms of reduced non-specific binding and mild effect in ABA but was usually complicated by an asymmetric antibody reduction due to mercaptoethylamine while carbohydrate oxidation based strategy performed the worst during our experiment.     

Organic Dyes Containing Pyrenylamine‐Based Cascade Donor Systems with Different Aromatic π Linkers for Dye‐Sensitized Solar Cells: Optical,Electrochemical, and Device Characteristics

New organic dyes containing pyrenylamine donors in a cascade arrangement and cyanoacrylic acid acceptors have been synthesized and characterized by optical, electrochemical, and theoretical studies. The dyes inherit a D ‐π¹‐D ‐π²‐A (D=donor, A=acceptor) molecular architecture where the π linkers π¹ are changed from phenyl to biphenyl and fluorene, whereas the π linker π² that connects the donor fragment with the acceptor is a phenyl unit. The conjugation pathway linking the two donor segments has been found to play a major role in the optical and electrochemical properties. Shorter π linkers such as phenyl groups facilitate the donor–acceptor interaction while the nonplanar biphenyl spacer decreases the electronic communication between the donors and enhances the oxidation propensity of the corresponding dye. All the dyes display an intense longer wavelength electronic transition,which is attributable to the amine‐to‐cyanoacrylic acid charge transfer. The extinction coefficient of this peak grows dramatically on increasing the conjugation pathway length between the two donor segments. The dyes were used as sensitizers in nanocrystalline TiO₂‐based dye‐sensitized solar cells (DSSCs) and the cascade donor system contributed to the enhancement in the device efficiency due to favorable absorption and redox properties.     

Mehar’s method for solving fuzzy sensitivity analysis problems with LR flat fuzzy numbers

In published works on fuzzy linear programming there are only few papers dealing with stability or sensitivity analysis in fuzzy mathematical programming. To the best of our knowledge, till now there is no method in the literature to deal with the sensitivity analysis of such fuzzy linear programming problems in which all the parameters are represented by LR flat fuzzy numbers. In this paper, a new method, named as Mehar’s method, is proposed for the same. To show the advantages of proposed method over existing methods, some fuzzy sensitivity analysis problems which may or may not be solved by the existing methods are solved by using the proposed method.     

Dynamical Casimir effect in superradiant light scattering by Bose–Einstein condensate in an optomechanical cavity

We investigate the effects of dynamical Casimir effect in superradiant light scattering by Bose-Einstein condensate in an optomechanical cavity. The system is studied using both classical and quantized mirror motions. The cavity frequency is harmonically modulated in time for both the cases. The main quantity of interest is the number of intracavity scattered photons. The system has been investigated under the weak and strong modulations. It has been observed that the amplitude of the scattered photons is more for the classical mirror motion than the quantized mirror motion. Also, initially, the amplitude of scattered photons is high for lower modulation amplitude than higher modulation amplitude. We also found that the behavior of the plots are similar under strong and weak modulations for the quantized mirror motion.     

β-cyclodextrin mediated synthesis of indole derivatives: reactions of isatins with 2-amino(or 2-thiole)anilines by supramolecular catalysis in water

An elegant, mild, and straightforward strategy for the synthesis of indole derivatives have been accomplished by the biomimetic catalysis for the first time in water under neutral conditions. This supramolecular catalyst oriented methodology provides a sustainable and green protocol for the synthesis of 6H-indolo[2,3-b]quinoxalines and 3H-spiro[benzo[d]thiazole-2,3’-indolin]-2’-one by the reaction of isatin derivatives with 1,2-difunctionalized benzene using β-cyclodextrin (β-CD) as a recoverable and reusable supramolecular catalyst.