Bandlike transport in strongly coupled and doped quantum dot solids: a route to high-performance thin-film electronics

We report bandlike transport in solution-deposited, CdSe QD thin-films with room temperature field-effect mobilities for electrons of 27 cm(2)/(V s). A concomitant shift and broadening in the QD solid optical absorption compared to that of dispersed samples is consistent with electron delocalization and measured electron mobilities. Annealing indium contacts allows for thermal diffusion and doping of the QD thin-films, shifting the Fermi energy, filling traps, and providing access to the bands. Temperature-dependent measurements show bandlike transport to 220 K on a SiO(2) gate insulator that is extended to 140 K by reducing the interface trap density using an Al(2)O(3)/SiO(2) gate insulator. The use of compact ligands and doping provides a pathway to high performance, solution-deposited QD electronics and optoelectronics.     

Effect of solution-processed niO thin film as a hole transport layer in poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid methyl ester bulk heterojunction solar cells

In this study, solution-processed nickel oxide (NiO) thin film was investigated as a hole transport layer on anode to improve the performance of bulk heterojunction solar cell based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). We fabricated NiO thin film without any vacuum-related process. Characterization of the NiO film under this study shows that it has maximum transmittance of 93.22% and bandgap of 3.84 eV which are proper for solar cell. Insertion of the NiO layer affords to realize enhanced power conversion efficiency of 1.97% and fill factor of 52.11% showing improvement over existing cells. In addition, NiO suggests one solution of minimizing conventional problems of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) such as interfacial power losses, corrosion of indium tin oxide layer, and degradation of the devices. The value of such hole transporting and electron blocking properties is clearly demonstrated and could be applicable to other organic photovoltaics.     

Study on the characteristics of amorphous low-K thin film for solar cells

The most practical solar cells are silicon based crystal silicon solar cells. Phosphorus oxychloride for n+ type doping was diffused on a p+ Si, SiC and poly Si using N2 carrier gas by low pressure chemical vapor deposition. The series resistances on various p type silicon substrates were researched. An n(+)-p+ junction was fabricated by thermal diffusion of phosphorus oxychloride into a p+ Si wafer. For the rear metallization, Al was deposited using screen printing and SiOC film was used instead of SiO2 film as a passivation material for the metal layer. SiOC film was made by the capacitive coupled plasma chemical vapor deposition. When the Fourier transform infrared spectra of SiOC film shows organic properties including a strong peak of the Si-CH3 bond, the efficiency was increased, because of the reduction of the recombination at the back surface.     

Preparation of C60(O)n-ZnO nanocomposite under electric furnace and photocatalytic degradation of organic dyes

Zinc oxide (ZnO) nanoparticles were synthesized sonochemically by applying ultrasonic irradiation to a mixed aqueous-alcoholic solution of zinc nitrate with sodium hydroxide at room temperature. The morphology and optical properties of the ZnO nanoparticles were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis spectroscopy. The C60(O)n nanoparticles were synthesized by heating a mixture of C60 and 3-chloroperoxybenzoic acid in a benzene solvent under the reflux system. The heated C60(O)n-ZnO nanocomposite was synthesized in an electric furnace at 700 degrees C for two hours. The heated C60(O)n-ZnO nanocomposite was characterized by XRD, SEM, and TEM, and examined as a catalyst in the photocatalytic degradation of organic dyes by UV-vis spectroscopy. The photocatalytic effect of the heated C60(O)n-ZnO nanocomposite was evaluated by a comparison with that of unheated C60(O)n nanoparticles, heated C60(O)n nanoparticles, and unheated C60(O)n-ZnO in organic dyes, such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultraviolet light at 365 nm.     

Characterization of carbon nanotube-cdse hybrid nanomaterials

MWNT-CdSe hybrid nanomaterials were prepared with carboxylic acid-treated CdSe nanoparticles and amino-functionalized MWNTs. The hybridization of MWNT-CdSe nanomaterials was performed by the formation of covalent bond between MWNT and CdSe. Their covalent bond lengths were varied with changing the linking spacers. Amino-functionalized MWNTs were reacted with CdSe nanoparticles which were functionalized with carboxylic acid groups. Their detailed structures were characterized by FT-IR, XPS, and small angle X-ray scattering. Through small angle X-ray scattering experiments, it was found that the structures of CdSe nanoparticles were not regular, and their sizes were broadly distributed in solution. The longer amino-functionalized MWNTs were thermally decomposed at lower temperature. The photoluminescence (PL) of chemically-linked MWNT-CdSe hybrid nanomaterials were weaker than that of CdSe nanoparticles. In addition, their PL intensities more weakened on the MWNT-CdSe with the longer spacers.     

Detection of dopamine in dopaminergic cell using nanoparticles-based barcode DNA analysis

Nanotechnology-based bio-barcode-amplification analysis may be an innovative approach to dopamine detection. In this study, we evaluated the efficacy of this bio-barcode DNA method in detecting dopamine from dopaminergic cells. Herein, a combination DNA barcode and bead-based immunoassay for neurotransmitter detection with PCR-like sensitivity is described. This method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA, and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated in order to remove the conjugated barcode DNA. The DNA barcodes were then identified via PCR analysis. The dopamine concentration in dopaminergic cells can be readily and rapidly detected via the bio-barcode assay method. The bio-barcode assay method is, therefore, a rapid and high-throughput screening tool for the detection of neurotransmitters such as dopamine.     

All solution processable organic photovoltaic cells using DMDCNQI as an organic N-type buffer layer

Organic photovoltaic cells consisting of ITO/PEDOT-PSS/P3HT:PCBM/TiO(x)/DMDCNQI/Al have been fabricated by using dip-coated DMDCNQI layer as a cathode buffer material. We have investigated the physical effects of charge transfer complex and wettability of DMDCNQI between TiO(x)/P3HT:PCBM layer and Al cathode electrode on the performance of organic photovoltaic cell. The photovoltaic cell fabricated with a dip-coated DMDCNQI layer exhibited almost similar performance compared to the device using conventional evaporated DMDCNQI layer. Especially, the power conversion efficiency of the prepared organic photovoltaic cell using TiO(x)/DMDCNQI layer was improved to 3.1%, which is mainly due to the decrease in the low contact resistance of organic-metal interface.     

Precursor solvent influence on preparation and electrochemical properties of platinum nanoparticles electrodes

The crystalline sizes and loading efficiencies of metallic nanoparticles for fuel cell catalysts have been measured by changing solvent species containing precursors. By changing the solvent species containing carbon particles and metal salt, the microstructure and the according electrochemical property of catalysts could be controlled. Four kinds of solvent were investigated in this study. Pt catalysts that were deposited on carbon blacks supports by using an ethylene glycol solution showed the highest deposition efficiency, 85% and smallest crystalline size, 2.85 nm of particles. From the experimental result, it was concluded that the electrochemical performance of catalysts was dependent on the crystalline size and deposition efficiency of metal particles, by changing solvent species.     

Cell chip-based monitoring of toxic effects of cosmetic compounds on skin fibroblast cells

The present study estimated the efficacy of electrochemical detection of imidazolidinyl urea-induced cell toxicity in skin human fibroblast cells (HFF cells). The gold nanopunct structures were fabricated through a nanoporous alumina mask, and the structural formations were confirmed via scanning electron microscopy. The HFF cells were allowed to attach to RGD (Arg-Gly-Asp) peptide nanopatterned surfaces, and electrochemical tools were applied to skin cells attached to the chip surface. The HFF cells evidenced inflammation responses to allergens such as imidazolidinyl urea. The cells were subsequently treated with different concentrations of imidazolidinyl urea for 24 h in culture, which induced a change in the cyclic voltammetry (CV) current peak. Treatment with imidazolidinyl urea induced a loss of cell viability and accelerated inflammation in a concentration-dependent manner. The expression level of inflammation-related proteins such as IL-1 beta were increased in imidazolidinyl urea-treated cells. The CV results demonstrated that imidazolidinyl urea significantly reduced the current peaks in a dose-dependent manner. The results showed that the current peak was reduced in accordance with the increases in imidazolidinyl urea-induced inflammation. In conclusion, the results of this study suggest that the electrochemical-based chip provides crucial information for improvements to a cell chip system for drug screening applications.