A 9% efficiency of flexible Mo-foil-based Cu2ZnSn(S,Se)4 solar cells by improving CdS buffer layer and heterojunction interface

Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recombination of CZTSSe/CdS heterojunction interface.We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils.The efficiency of the device is improved from 5.7%to 6.86%by highquality junction interface.Furthermore,aiming at the S loss of CdS film,the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality.The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05%efficiency with a VOC of 0.44 V at an optimized S source concentration of 0.68 mol/L.Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the VOCdeficit.For the CZTSSe device bending characteristics,the device efficiency is almost constant after1000 bends,manifesting that the CZTSSe device has an excellent mechanical flexibility.The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.

Is there A Link between Serum Thyroid Stimulating Hormone Level and the Results of in vitro Fertilization and Embryo Transfer?

Objective To analyze the clinical features and outcomes in infertile patients with different levels of thyroid stimulating hormone （TSH） undergoing IVF/ICSL and to investigate whether inappropriate level of TSH has the adverse effect on the results of the IVF-ET.Methods A total of 389 patients undergoing IVF/ICSI from January 2009 to December 2011 were divided into 3 groups according to the basal TSH level： group A （TSH〈 2.0 mlU/L）, group B （TSH 2.0-4.5 mlU/L） and group C （TSH〉4.5 mlU/L）. Oocyte retrieved, fertilization rate, cleavage rate, available embryo rate, pregnancy rate and miscarriage rate were analyzed to explore whether serum TSH level was correlated with the results of lVF/ICSI.Results There were no differences in number of oocyte retrieved, fertilization rate, cleavage rate and available embryo rate among 3 groups （P〉0.05）. Clinical pregnancy rate in group B （43.0%） was significantly higher than that in group A （30.2%） and group B （23.5%）, respectively （P〈0.05）. There were no significant differences in miscarriage rate among 3 groups.Conclusion TSH level has no effect on fertility rate or miscarriage rate in patients undergoing IVF/ICSL Inadequacy TSH level would decrease the IVF/ICSI pregnancy rate.