Qinmiao Chen

Study and enhance the photovoltaic properties of narrow-bandgap Cu2SnS3 solar cell by p–n junction interface modification

Photovoltaic properties of narrow-bandgap Cu(2)SnS(3) (CTS) are studied for the first time by employing a superstrate solar cell structure of fluorine-doped tin oxide (FTO) glass/TiO(2)/In(2)S(3)/CTS/Mo. The structural, optical, and electronic characteristics of the CTS make it great potential as bottom cell absorber material for low-cost thin film tandem solar cell application. Furthermore, by inserting a thin low temperature deposited In(2)S(3) layer between the In(2)S(3) buffer layer and the CTS absorber layer, an enhancement in the performance of the solar cell can be achieved, leading to about 75% improvement (η=1.92%) over the unmodified device (η=1.10%).

The photovoltaic properties of novel narrow band gap Cu2SnS3 films prepared by a spray pyrolysis method

The ternary compound Cu2SnS3 (CTS) was fabricated by a spray pyrolysis method. The influence of the Cu precursor concentration and substrate temperature on the properties of the prepared films was investigated in detail. X-ray diffraction spectroscopy & Raman spectroscopy, energy dispersive spectroscopy, UV-vis spectrophotometry, Four-probe Resistivity Testing and Stylus Profilometry were employed for the analysis of the structural, compositional, optical, electrical and morphological properties of the prepared CTS thin films. The characterization results showed that the CTS thin film fabricated under optimal conditions (substrate temperature 350 °C, Cu concentration 0.02 M) had an atomic ratio of Cu1.43SnS2.59, and presented as a tetragonal structure with preferential (1, 1, 2) orientation. Optical measurements showed that the thin film had a high absorption coefficient (>104 cm−1) with a band gap value of 1.16 eV. The resistivity of the sprayed CTS thin film was 11.6 × 10−2 Ω cm. All these properties indicated that the as-fabricated CTS thin film could be a promising absorber layer material for high efficiency thin film solar cells.

Printed ethyl cellulose/CuInSe2 composite light absorber layer and its photovoltaic effect

A novel ethyl cellulose/CuInSe2 (CISe) composite light absorber layer and its photovoltaic effect are reported. The precursor absorber layer was deposited from screen printing paste containing ethyl cellulose and CISe powder, and was followed by rapid thermal annealing. Experimental results indicated that the ethyl cellulose remained in the annealed absorber layer, and the composite absorber layer may consist of ethyl cellulose/CISe composite shell/core structure. The structural, optical and electronic properties of the composite absorber layer were fully investigated. The composite absorber layer shows photovoltaic efficiency of 0.65% under standard test condition.

Is pulsed electric field still effective for RNA separation in capillary electrophoresis

Pulsed field capillary electrophoresis (PFCE) is a predominant technique to cope with difficulties in resolving large DNA strands, yet it is still unclear whether pulsed electric field is effective for the separation of higher mass RNA. In this paper we focused on the role of pulsed electric field in large RNA fragments analysis by comparing RNA separation performance in PFCE with that in constant field CE. Separation performance in terms of migration mobility, plate numbers, resolution, and selectivity has been tested for the analysis of RNA from 0.1 to 10.0 kilo nucleotide (knt) under different electrophoretic conditions. Denaturation, important to obtain uniform and identifiable peaks, was accomplished by heating the sample in 4.0M urea prior to analysis and the presence of 4.0M urea in the electrophoresis buffer. Results demonstrate that unlike DNA in PFCE, the pulsed electric field mainly affects the separation performance of RNA between 0.4 and 2.0 knt. The migration mobility of long RNA fragments is not a strong function of modulation depth and pulsed frequency. Moreover, the logarithm of RNA mobility is almost inversely proportional to the logarithm of molecule size up to 6.0 knt with correlation coefficient higher than 0.99 in all the polymer concentrations measured here. Resonance frequency of RNA in PFCE was also observed. While these initial experiments show no distinct advantages of using PFCE for RNA separation, they do take further step toward characterizing the migration behavior of RNA under pulsed field conditions.

Rapid identification and quantitation for oral bacteria based on short-end capillary electrophoresis

High-speed capillary electrophoresis (HSCE) is a promising technology applied in ultra-rapid and high-performance analysis of biomolecules (such as nucleic acids, protein). In present study, the short-end capillary electrophoresis coupled with one novel space domain internal standard method (SDIS) was employed for the rapid and simultaneous analysis of specific genes from three oral bacteria (Porphyromonas gingivalis (P.g), Treponema denticola (T.d) and Tannerela forsythia (T.f)). The reliability, reproducibility and accuracy properties of above mentioned SDIS method were investigated in detail. The results showed the target gene fragments of P.g, T.d and T.f could be precisely, fast identified and quantitated within 95s via present short-end CE system. The analyte concentration and the ratio of space domain signals (between target sample and internal standard sample) featured a well linear relationship calculated via SDIS method. And the correlation coefficients R(2) and detection limits for P.g, T.d, T.f genes were 0.9855, 0.9896, 0.9969 and 0.077, 0.114 and 0.098ng/μl, respectively.

Theoretical investigation on the performance of DNA electrophoresis under programmed step electric field strength: Two-step condition

Programmed step electric field strength is a simple-to-use technique that has already been reported to be effective to enhance the efficiency or speed of DNA electrophoresis. However, a global understanding and the details of this technique are still vague. In this paper, we investigated the influence of programmed step electric field strength by theoretical calculation and concentrated on a basic format named as two-step electric field strength. Both subtypes of two-step electric field strength conditions were considered. The important parameters, such as peak spacing, peak width, resolution, and migration time, were calculated in theory to understand the performance of DNA electrophoresis under programmed step electric field strength. The influence of two-step electric field strength on DNA electrophoresis was clearly revealed on a diagram of resolution versus migration time. Both resolution and speed of DNA electrophoresis under two-step electric field strength conditions are simply expressed by the shape of curves in the diagram. The possible shapes of curve were explored by calculation and shown in this paper. The subtype II of two-step electric field strength brings drastic variation on the resolution. Its limitations of enhancement and deterioration of resolution were predicted in theory.

The effect of processing on the properties of CuInS2 nanomaterials synthesized by simple hot injection route

Chalcopyrite and wurtzite CuInS2 (CIS) nanomaterials were synthesized from Cu2+, In3+, thiourea with or without triethanolamine (TEA) by simple hot injection method at low temperature. The effect of synthesis duration on the various properties of the synthesized CIS nanomaterials was studied. It shows that for chalcopyrite CIS, the optimal synthesis duration is 60 min and the synthesized nanomaterial is in spherical shape with diameter of about 90 nm. However, for the wurtzite CIS, the optimal synthesis duration should reach 150 min and the synthesized nanomaterial looks like nanoplate with thicknesses of ∼10 nm and diameters near 100 nm. The photovoltaic characteristics of two types of nanomaterials are quite different. This study may contribute to the synthesis of CIS nanomaterials at low temperatures.