Investigation of the effect of CdCl2 processing on vacuum deposited CdS/CdTe thin film solar cells by DLTS

Thin film CdS/CdTe solar cells have been prepared by conventional vacuum deposition technique. Deep level transient spectroscopy (DLTS), temperature and frequency dependent capacitance-voltage (C-V) measurements were utilised to investigate the performance limiting defect states in the CdTe layer subjected to the post deposition treatments such as CdCl₂-dipping and/or annealing in air. Five hole traps, all of which have been previously reported in the literature, were identified in as-grown CdTe at 0.19, 0.20, 0.22, 0.30 and 0.40 eV above the valence band. A single hole trap level has been evidenced at 0.45 eV after both post deposition heat and CdCl₂ treatments.     

Synthesis, spectroscopic and electrochemical studies on bis-[1,3-substituted (Cl, Br) phenyl-5-phenyl formazanato]nickel(II) complexes

In this study, new 1:2 Ni complexes of 1,3-substituted phenyl-5-phenylformazans were synthesized with -Cl, -Br substituents in the o-, m-, p-positions of the 1-phenyl ring and -NO(2) group in the m-position of the 3-phenyl ring. Their structures were elucidated and spectral behaviors were investigated with the use of elemental analysis, GC-Mass, (1)H NMR, (13)C NMR, FTIR, UV-vis spectra. Furthermore electrochemical properties such as number of electrons transferred (n), diffusion coefficients (D) and possible reaction mechanism of the compounds were determined with the use of cyclic voltammetry, ultramicrodisc electrode and chronoamperometry. The relation between their absorption properties and electrochemical properties was examined. A linear correlation was obtained between Hammett substituent coefficients with lambda(max) values.     

Synthesis and characterization of novel phthalocyanines bearing quaternizable coumarin

The synthesis of novel metal-free and zinc phthalocyanines with four 3-[(2-diethylamino)ethyl]-7-oxo-4-methylcoumarin dye groups on the periphery were prepared by cyclotetramerization of a novel 3-[(2-diethylamino)ethyl]-7-[(3,4-dicyanophenoxy)]-4-methylcoumarin. The novel chromogenic compounds were characterized by elemental analysis, ¹H NMR, ¹³C NMR, MALDI-TOF, IR and UV–Vis spectral data. The electronic spectra exhibit bands of coumarin identity along with characteristic Q and B bands of the phthalocyanine (Pc) core. The IR spectra of all the Pcs showed three characteristic intense bands, at 1704 cm⁻¹ for the lactone carbonyl and two bands at 1489–1604 cm⁻¹ for the conjugated olefinic system.     

N‐(4‐Methoxy­benzyl­idene)‐N′‐(2‐pyridyl)­hydrazine

Molecules of the title compound (alternative name p‐methoxybenzaldehyde 2‐pyridyl­hydrazone), C₁₃H₁₃N₃O, adopt an E configuration about the azomethine C=N double bond. Molecules are almost planar, the dihedral angle between the pyridine and methoxy­phenyl rings being only 6.19 (12)°. Pairwise N—H⃛N hydrogen bonds [R(8) in graph‐set notation] link centrosymmetrically related mol­ecules into discrete pairs.     

Dipolar cycloadditions of imidazoline 3-oxides with N-arylmaleimides. Synthesis and diethylamine induced ring-opening of exo and endo hexahydro-7-oxa-2,5,6a-triaza-cyclopenta[a]pentalene-1,3-diones

1,4-Diarylimidazoline 3-oxides react with N-arylmaleimides in benzene to give predominantly the corresponding endo adducts. Chiral imidazoline 3-oxides react diastereospecifically (cis configuration of the tetrahydroimidazo ring) and diastereoselectively to give cis-endo adducts. The effects of substituents on the aromatic ring of the maleimide was investigated. The presence of electron-withdrawing or releasing groups have minor effect on the total yields but more pronounced is the effect on the ratio of exo and endo diastereomers. The adducts undergo an interesting and unprecedented ring-opening in the presence of secondary amines to give deoxygenated 3-imidazoline 3-oxides instead of the expected double cis elimination products. Tertiary amines did not induce any reaction.     

Synthesis and spectral properties of some bis-substituted formazans

Novel, 1,4-bis-[3,3'-phenyl-5,5'-(o-carboxyphenyl)-formaz-1-yl]-benzene-o-sulphonic acid and its derivatives contained OH group at the o-, m-, p-positions of the 3-phenyl ring were synthesized. The structures of the formazans were confirmed by elemental analyses, GC-mass, IR, (1)H NMR, UV-vis spectra. Their absorption properties were investigated. It was seen that lambda(max) values shifted towards shorter wave lengths by 130nm in CSPF relative to 1,3,5-triphenylformazan (TPF) due to the fact that the structure of CSPF contained electron withdrawing COOH and SO(3)H groups (hypsochromic effect). With binding of OH group to 3-phenyl ring of CSPF, it was observed a small bathochromic effect in accordance to the electron donating effect of OH group.     

Crystal structure of 2,3-diaza-1,3-diphenylpropene.

The title compound crystallizes in monoclinic space group P2(1)/c. There are two molecules in the asymmetric unit. While one of these molecules is in a general position, the other is in disordered position. The angle between the directions of the molecules in the asymmetric unit is 87.5(1) degrees.     

Chemical modification of alumina surface by immobilization of 1-((5-nitrofuran-2-yl)methylene)thiosemicarbazide for extractive concentration of silver ions

A column, solid phase extraction (SPE), preconcentration method was developed for determination of silver by using alumina coated with 1-((5-nitrofuran-2-yl)methylene)thiosemicarbazide and determination by flame atomic absorption spectrometry. The separation/preconcentration conditions for the quantitative recovery were investigated. At pH 2, the maximum sorption capacity of Ag⁺ was 7.5?mg?g^?1. The linearity was maintained in the concentration range of 0.02–11.0?µg?mL^?1 in the final solution or 0.14–1.10?×?10^4?ng?mL^?1 in the original solution for silver. The preconcentration factor of 140 and relative standard deviation of ±1.4% was obtained, under optimum conditions. The limit of detection (LOD) was calculated as 0.112?ng?mL^?1, based on 3σ_bl/m (n?=?8) in the original solutions. The proposed method was successfully applied to the determination trace amounts of silver in the environmental samples such as tea, rice and wheat flour, mint, and real water samples.     

Electrochemical investigation of 1,3,5-triphenylformazan and its nitro derivatives in dimethyl sulfoxide.

Cyclic voltammetric (CV) and chronoamperometric (CA) behaviors of 1,3,5-triphenylformazan (TPF), 3-(p-nitrophenyl)-1,5-diphenylformazan (PNF) and 3-(m-nitrophenyl)-1,5-diphenylformazan (MNF) were studied in dimethyl sulfoxide medium. TPF was found to give a single sharp cathodic CV peak corresponding to a gain of one-electron per molecule. The diffusion coefficient and the number of electrons transferred were calculated using the Baranski equation with the CV-data obtained by an ultramicroelectrode. Standard rate constants for the reduction were calculated by the Klingler-Kochi technique. The electrochemical data obtained support the mechanism proposed by Umemoto.     

Frequency dependence of junction capacitance of BPW34 and BPW41 p-i-n photodiodes

This article investigates the frequency dependence of small-signal capacitance of silicon BPW34 and BPW41 (Vishay) p-i-n photodiodes. We show that the capacitance-frequency characteristics of these photodiodes are well-described by the Schibli and Milnes model. The activation energy and the concentration of the dominant trap levels detected in BPW34 and BPW41 are 280–330 meV and 1.1×10¹²−1.2×10¹² cm⁻³, respectively. According to the high-frequency C-V measurements, the impurity concentrations are determined to be about 5.3×10¹² and 1.9×10¹³ cm⁻³ in BPW41 and BPW34, respectively using the method of ΔV/Δ(C ⁻²) vs. C.