Yupeng Xing

Plasma assisted fabrication of multi-layer graphene/nickel hybrid film as enhanced micro-supercapacitor electrodes

A facile synthesis strategy has been developed for fabricating multi-layer graphene/nickel hybrid film as micro-supercapacitor electrodes by using plasma enhanced chemical vapor deposition. The as-presented method is advantageous for rapid graphene growth at relatively low temperature of 650 °C. In addition, after pre-treating for the as-deposited nickel film by using argon plasma bombardment, the surface-to-volume ratio of graphene film on the treated nickel substrate is effectively increased by the increasing of surface roughness. This is demonstrated by the characterization results from transmission electron microscopy, scanning electron microscope and atomic force microscopy. Moreover, the electrochemical performance of the resultant graphene/nickel hybrid film as micro-supercapacitor working electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. It was found that the increase of the surface-to-volume ratio of graphene/nickel hybrid film improved the specific capacitance of 10 times as the working electrode of micro-supercapacitor. Finally, by using comb columnar shadow mask pattern, the micro-supercapacitor full cell device was fabricated. The electrochemical performance measurements of the micro-supercapacitor devices indicate that the method presented in this study provides an effective way to fabricate micro-supercapacitor device with enhanced energy storage property.

Investigation of the forming process and characteristics of Al-BSF in silicon solar cells

This paper is intended to give insights into the forming process and characteristics of aluminum back surface field (Al-BSF) made by thermal evaporation and conventional thermal processing. It is indicated that Al-BSF formation is the result of the recrystallization of silicon and the dissolved silicon is responsible for the BSF thickness. A sufficient oxygen supply at the early stage of firing process is essential to thicken and strengthen oxide layer to protect the liquid aluminum and silicon during firing. It will be formed Al-BSF/Al-Si eutectic/Al2O3 multilayer structure at the back side of Si solar cells and the X-ray measurement demonstrates that the eutectic layer mainly contains Al3.21Si0.47. The Al-BSF has good electrical properties compared with boron-doped p+-Si by Hall tests. Solar cell with Al-BSF significantly increases long-wavelength response compared with the cells with diffused or ion implanted boron-BSF, and the back surface recombination velocity can be reduced as low as to 200 cm/s for Al-BSF passivation.