The High Surface Ratio Micro-MoS₂Grain Composed of MoS₂Nanosheet Prepared with One-Step Hydrothermal Synthesis

Micro molybdenum disulfide was prepared with one-step hydrothermal method;the influence of reactant concentration and temperature on the surface ratio of micro-MoS2 grain was investigated. Raman spectroscopy (Raman), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) were used to characterize the structure, composition and morphology of MoS2. The results show that micro-MoS2 grains were synthesized with one-step hydrothermal synthesis, and the morphology of micro-MoS2 grains is like flower and sphere. The SEM figures indicate that the surface ratio of micro-MoS2 grains is different and also show that the surface ratio of micro-MoS2 grains can be improved by regulating reactant concentration and temperature. This research showed a method to improve the surface ratio of micro-MoS2 grains.

Simulation and Optimization Characteristic of Novel MoS₂/c-Si HIT Solar Cell

Monolayer MoS2 has excellent optoelectronic properties, which is a potential material for solar cell. Though MoS2/c-Si heterojunction solar cell has been researched by many groups, little study of MoS2/c-Si solar cell physics is reported. In this paper, MoS2/c-Si heterojunction solar cells have been designed and optimized by AFORS-HET simulation program. The various factors affecting the performance of the cells were studied in details using TCO/n-type MoS2/i-layer/p-type c-Si/BSF/Al structure. Due to the important role of intrinsic layer in HIT solar cell, the effect of different intrinsic layers including a-Si:H, nc-Si:H, a-SiGe:H, on the performance of TCO/n-type MoS2/i-layer/p-type c-Si/Al cell, was studied in this paper. The results show that the TCO/n-type MoS2/i-layer/p-type c-Si/Al cell has the highest efficiency with a-SiGe:H as intrinsic layer, efficiency up to 21.85%. The back surface field effects on the properties of solar cells were studied with p + μc-Si and Al as BSF layers. And the effect of various factors such as thickness and band gap of intrinsic layer, thickness of MoS2, density of defect state and the energy band offset of MoS2/c-Si interface of TCO/n-type MoS2/i-layer nc-Si:H/p-type c-Si/Al cells, on the characteristics of solar cells, have been discussed for this kind of MoS2 heterojunction cells. The optimal solar cell with structure of TCO/n-type MoS2/i-type nc-Si:H/p-type c-Si/BSF/Al, has the best efficiency of 27.22%.

A Magentoelectric Coefficient Measurement System with a Free-Stress Sample Holder

With less extra stress on the testing sample, a free-stress sample holder was designed to place the sample horizontally. With the free-stress sample holder, a magnetoelectric (ME) coefficient measurement system was developed based on dynamic method. This measurement system has the hardware part and the software part, integrated by the DC magnetic field generation module, the AC magnetic field generation module, the induced ME voltage detecting module and PC software module. Then, a sample of Terfenol-D/PZT/Terfenol-D trilayer was designed and fabricated, and the relationships of its ME coefficient influenced by the DC magnetic field and the frequency of the AC magnetic field were tested using the measurement system. And the results showed that the free-stress sample holder was proven to improve the accuracy of the measurement system by less stress interference.

Synthesis of two-dimensional transition metal dichalcogenides for electronics and optoelectronics

Tremendous efforts have been devoted to preparing the ultrathin two-dimensional(2D)transition-metal dichalcogenides(TMDCs)and TMDCS-based heterojunctions owing to their unique properties and great potential applications in next generation electronics and optoelectronics over the past decade.However,to fulfill the demands for practical applications,the batch production of 2D TMDCs with high quality and large area at the mild condi-tions is still a challenge.This feature article reviews the state-of-the art research progresses that focus on the preparation and the applications in elec-tronics and optoelectronics of 2D TMDCs and their van der Waals hetero-junctions.First,the preparation methods including chemical and physical vapor deposition growth are comprehensively outlined.Then,recent progress on the application of fabricated 2D TMDCs based materials is revealed with particular attention to electronic(eg,field effect transistors and logic circuits)and optoelectronic(eg,photodetectors,photovoltaics,and light emitting diodes)devices.Finally,the challenges and future prospects are considered based on the current advance of 2D TMDCs and related heterojunctions.

Polyplex interaction strength as a driver of potency during cancer immunotherapy

Many experimental cancer vaccines are exploring toll-like receptor agonists （TLRas） such as CpG, a DNA motif that agonizes toll-like receptor 9 （TLR9）, to trigger immune responses that are potent and molecularly-specific. The ability to tune the immune response is especially important in the immunosuppressive microenvironments of tumors. Because TLR9 is located intracellularly, CpG must be internalized by immune cells for functionality. Polyplexes can be self- assembled through electrostatics using DNA （anionic） condensed by a positively charged carrier. These structures improve cell delivery and have been widely explored for gene therapy. In contrast, here we use cationic poly （^-amino esters） （PBAEs） to assemble polyplexes from CpG as an adjuvant to target and improve immune stimulation in cells and mouse models. Polyplexes were formed over a range of PBAE：CpG ratios, resulting in a library of complexes with increasingly positive charge and stronger binding as PBAE：CpG ratio increased. Although higher PBAE：CpG ratios exhibited improved CpG uptake, lower ratios of PBAE：CpG--which condensed CpG more weakly, activated DCs and tumorspecific T cells more effectively. In a mouse melanoma model, polyplexes with lower binding affinities improved survival more effectively compared with higher binding affinities. These data demonstrate that altering the polyplex interaction strength impacts accessibility of CpG to TLRs in immune cells. Thus, physiochemical properties, particularly the interplay between charge, uptake, and affinity, play a key role in determining the nature and efficacy of the immune response generated. This insight identifies new design considerations that must be balanced for engineering effective immunotherapies and vaccines.

Structural, optical and electrical properties of ZnO： B thin films with different thickness for bifacial a-Si：H/c-Si heterojunction solar cells

Textured surface boron-doped zinc oxide （BZO） thin films were fabricated by metal organic chemical vapor deposition as transparent conductive oxide （TCO） for solar cells. The surface microstructure was characterized by X-ray diffraction spectrum and scan- ning electron microscope. The optical transmittance was shown by optical transmittance microscope and the electrical properties were tested by Hall measurements. The thickness of the BZO film has crucial impact on the surface morphology, optical transmittance, and resistivity. The electrical and optical properties as well as surface microstructure varied inconsistently with the increase of the film thickness. The grain size and the surface roughness increased with the increase of the film thickness. The conductivity increased from 0.96x 103 tO 6.94x 103 S/cm while the optical transmittance decreased from above 85% to nearly 80% with the increase of film thickness from 195 to 1021 nm. The BZO films deposited as both front and back transparent electrodes were applied to the bifacial p- type a-Si：H/i-type a-Si：H/n-type c-Si/i-type a-Si：H/n＋-type a-Si：H heterojunction solar cells to obtain the optimized parameter of thickness. The highest efficiency of all the samples was 17.8% obtained with the BZO film thickness of 829 nm. Meanwhile, the fill factor was 0.676, the open- circuit voltage was 0.63 Vand the short-circuit density was 41.79 mA/cm2. The properties of the solar cells changing with the thickness were also investigated.

Texturization and rounded process of silicon wafers for heterojunction with intrinsic thin-layer solar cells

Heterojunction with intrinsic thin-layer （HIT） solar cells are sensitive to interface state density. Tradi- tional texture process for silicon solar cells is not suitable for HIT one. Thus, sodium hydroxide （NaOH）, isopropanol （IPA） and mixed additive were tentatively introduced for the texturization of HIT solar cells in this study. Then, a mixture including nitric acid （HNO3）, hydrofluoric acid （HF） and glacial acetic acid （CH3COOH） was employed to round pyramid structure. The morphology of textured surface and the influence of etching time on surface reflectance were studied, and the relationship between etching time and surface reflectance, vertex angle of pyramid structure was analyzed. It was found that the mixture consisting of 1.1 wt% NaOH, 3 vol% IPA and 0.3 vol% additives with etching time of 22.5 min is the best for H1T solar cells under the condition of 80℃. Uniform pyramid structure was observed and the base width of pyramid was about 2-4 μm. The average surface reflec- tance was 11.68%. Finally the effect of different processes on the performance of HIT solar cells was investigated. It was shown that these texturization and rounding techni- ques used in this study can increase short circuit current （Jsc）, but they have little influence on fill factor （FF） and open circuit voltage （Voo） of HIT solar cells.