Two-dimensional spiral plasmonic structures have emerged as a versatile approach to generate near-field vortex fields with tunable topological charges. We demonstrate here a far-field approach to observe the chiral second-harmonic generation (SHG) at designated visible wavelengths from a single plasmonic vortex metalens. This metalens comprises an Archimedean spiral slit fabricated on atomically flat aluminum epitaxial film, which allows for precise tuning of plasmonic resonances and subsequent transfer of two-dimensional materials on top of the spiral slit. The nonlinear optical measurements show a giant SHG circular dichroism. Furthermore, we have achieved an enhanced chiral SHG conversion efficiency (about an order of magnitude greater than the bare aluminum lens) from monolayer tungsten disulfide (WS 2 )/aluminum metalens, which is designed at the C-exciton resonance of WS 2 . Since the C-exciton is not a valley exciton, the enhanced chiral SHG in this hybrid system originates from the plasmonic vortex field-enhanced SHG under the optical spin−orbit interaction.

The performance of black silicon solar cells with various passivation films was characterized. Large area (156×156 mm2) black silicon was prepared by silver-nanoparticle-assisted etching on pyramidal silicon wafer. The conversion efficiency of black silicon solar cell without passivation is 13.8%. For the SiO2andSiNx:H passivation, the conversion efficiency of black silicon solar cells increases to 16.1% and 16.5%, respectively. Compared to the single film of surface passivation of black silicon solar cells, the SiO2/SiNx:H stacks exhibit the highest efficiency of 17.1%. The investigation of internal quantum efficiency (IQE) suggests that the SiO2/SiNx:H stacks films decrease the Auger recombination through reducing the surface doping concentration and surface state density of the Si/SiO2interface, andSiNx:H layer suppresses the Shockley-Read-Hall (SRH) recombination in the black silicon solar cell, which yields the best electrical performance of b-Si solar cells.

To improve the structure order and catalytic activity of mesoporous materials, cubic (SBU-MCM-48) and hexagonal (SBU-MCM-41) mesoporous aluminosilicates containing secondary building units characteristic of zeolite Beta have been prepared, and characterized by means of XRD, N2 adsorption, IR spectroscopy, catalytic cracking reaction compared with the corresponding MCM-41. We found that the introduction of secondary building units characteristic of zeolite Beta into the mesopore wall could be an effective route to improve the acidity of mesoporous materials. Moreover, cubic SBU-MCM-48 has been more active than hexagonal SBU-MCM-41 for cumene cracking reaction.