Back contact–absorber interface modification by inserting carbon intermediate layer and conversion efficiency improvement in Cu2ZnSn(S,Se)4 solar cell

Carbon layers have been employed as intermediate layers between Mo back contact and Cu₂ZnSn(S_1–xSe_x)₄(CZTSSe) absorber film prepared by sol–gel and post‐selenization method. Carbon layers with appropriate thickness can significantly inhibit the formation of MoSe₂ and voids at bottom region of the absorber, and therefore reduce the series resistance remarkably. The conversion efficiency can be boosted by the introducing of the carbon layer from 6.20% to 7.24% by enhancement in short current density, fill factor and open voltage in comparison to the reference sample without carbon layer. However, excess thickness of carbon layer will worse device performance due to the deteriorated absorber crystallinity. In addition, the time‐resolved photoluminescence analysis shows that inserting the carbon layer with suitable thickness does not introduce recombination and lower minority lifetime. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Dynamic analysis on metal selenide electrodeposition

Based on the basic principles of kinetics and some reasonable assumptions about the electrodeposition process, a dynamic model for metal selenide electrodeposition (kink site selected model) was constructed. This model is of universal significance in realizing the compositional prediction and dynamic behavior analysis of deposited films for different main salt concentration ratios and was applied to the ternary Cu–In–Se system. For CuInSe₂ electrodeposition, in the Cu–Se system, the co-deposition of Cu and Se can be carried out within a large range of main salt concentration ratio; in the Cu–In system, the mole fraction of Cu in deposited thin films is always higher than that of Cu²⁺ in electrolyte, while in the In–Se system, the co-deposition of In and Se can be achieved only when the In³⁺ concentration is much higher than the H₂SeO₃ concentration. As for the compositional estimation of CuInSe₂, the predictive results of our dynamic model agree well with the experimental data. It is then found that by correcting the difference of kink site selectivity constants caused by the change of deposition potential, the error of the predictive results can be reduced.     

Generation of anti-trenbolone monoclonal antibody and establishment of an indirect competitive enzyme-linked immunosorbent assay for detection of trenbolone in animal tissues, feed and urine

Trenbolone (TRE) is a steroid used by veterinarians on livestock to increase appetite and body weight. The use of TRE has been restricted because of its harmful side effect for consumers. To effectively control TRE residue in food and food product, a rapid and convenient immunoassay was developed by preparing an anti-TRE monoclonal antibody. The immunogen and coating antigen were prepared by coupling TRE hapten with carrier proteins via 1-ethyl-3-(dimethylaminopropyl)carbodiimide hydrochloride (EDC) method. The optimized method gave an average IC₅₀ value of 0.323 ng mL⁻¹ towards TRE and an average detection limit (LOD) of 0.06 ng mL⁻¹, which is much lower than the maximum residue levels (2.0 ng g⁻¹) accepted by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The specificity of the antibody was evaluated by measuring cross-reactivity of six structurally related compounds, including 19-nortestosterone (9.7%), testosterone (0.13%), methyltestosterone (<0.01%), methandrostenolone (<0.01%), (+)-dehydroisoandrosterone (<0.001%) and β-estradiol (<0.001%). The recovery rates of the test in detection of TRE-fortified animal tissue, urine and animal feed samples were in the range of 81.3-89.4%, while the intra- and inter-assay coefficients of variation were less than 12.0%.     

Comparison and vanishing theorems for Kähler manifolds

In this paper, we consider orthogonal Ricci curvature \(Ric^{\perp }\) for Kähler manifolds, which is a curvature condition closely related to Ricci curvature and holomorphic sectional curvature. We prove comparison theorems and a vanishing theorem related to these curvature conditions, and construct various examples to illustrate subtle relationship among them. As a consequence of the vanishing theorem, we show that any compact Kähler manifold with positive orthogonal Ricci curvature must be projective. This result complements a recent result of Yang (RC-positivity, rational connectedness, and Yau’s conjecture. arXiv:1708.06713) on the projectivity under the positivity of holomorphic sectional curvature. The simply-connectedness is shown when the complex dimension is smaller than five. Further study of compact Kähler manifolds with \(Ric^{\perp }>0\) is carried in Ni et al. (Manifolds with positive orthogonal Ricci curvature. arXiv:1806.10233).     

Improving Cu2ZnSnS4 (CZTS) solar cell performance by an ultrathin ZnO intermediate layer between CZTS absorber and Mo back contact

The effects of an ultrathin ZnO intermediate layer deposited at the CZTS/Mo interface on CZTS solar cell performance have been investigated in this work. The ZnO layer inhibits the generation of MoS₂ layer and the formation of voids in the CZTS absorber. Consequently, the incorporation of this layer reduces the series resistance and increases the shunt resistance, which boosts photovoltaic conversion efficiency from 1.13% to 4.3%. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

A local and global splitting result for real Kähler Euclidean submanifolds

We show that if a real Kähler Euclidean submanifold is as far as possible of being minimal, then it should split locally as a product of hypersurfaces almost everywhere, possibly in lower codimension. In addition, if the manifold is complete, simply connected and has constant nullity, it should split globally as a product of surfaces in and an Euclidean factor. Several applications are also given.Received: 28 May 2004     

Synthesis and characterizations of quaternary Cu2FeSnS4 nanocrystals

Quaternary tetragonal Cu(2)FeSnS(4) nanocrystals have been synthesized by a simple hot-injection method. Detailed characterizations have been made. A suitable optical band gap of 1.28 ± 0.02 eV and a notable and stable photoelectrochemical response indicate their potential for application in solar cells.     

Template-directed synthesis of ordered iron pyrite (FeS2) nanowires and nanotubes arrays

Highly ordered iron pyrite (FeS₂) nanowires and nanotubes arrays have been fabricated by using sol–gel method with AAO templates. The prepared nanowires and nanotubes have uniform lengths and 200 nm diameters. Their crystal phase was identified as cubic FeS₂ by using X-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy and selected-area electron diffraction pattern. The direct optical band gaps of the as-prepared FeS₂ nanowires were 0.98 and 1.23 eV, respectively, indicating their suitability for photovoltaic application.     

基于Monte Carlo方法模拟薄膜生长

本文运用Monte Carlo方法,通过计算机模拟研究了真空镀膜过程中沉积速率、自由粒子迁移率、粒子沿分形迁移等对薄膜生长过程的影响。     

Some recent progress in non-Kähler geometry

Science China Mathematics - In this paper, we discuss some recent progress in the study of non-Kähler manifolds, in particular the Hermitian geometry of flat canonical connections and...