Impurity-mediated near-infrared (NIR) photoresponse in silicon is of great interest for photovoltaics and photodetectors. In this paper, we have fabricated a series of n+/p photodetectors with hyperdoped silicon prepared by ion-implantation and femtosecond pulsed laser. These devices showed a remarkable enhancement on absorption and photoresponse at NIR wavelengths. The device fabricated with implantation dose of 1014 ions/cm2 has exhibited the best performance. The proposed method offers an approach to fabricate low-cost broadband silicon-based photodetectors.

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In this paper, we investigate the dependence of NIR absorption of hyper-doped silicon on different sulfur and nitrogen doping ratio. With different molecular proportion of N 2 and SF 6 background gas, femtosecond laser irradiation was used to implant co-doping of sulfur and nitrogen into silicon. The hyper-doped silicon presents high absorption properties in NIR and visible range. The results of first-principles calculations demonstrate the high absorption in NIR is ascribed to the induced impurity energy levels in hyper-doped silicon. The nitrogen doping process improves the crystallinity in the doped layer because the doped nitrogen repairs defects in silicon lattices. Given the thermal stability of nitrogen, the co-doping dopants limit the diffusion of sulfur during the annealing process. The co-doping process proposed in this paper provides a method to fabricate high performance NIR silicon optoelectronic device.

Despite dramatically improved efficiency of inorganic-organic metal hybrid perovskite solar cells (PSCs), electron transport is still a challenging issue. In this paper, we report the use of hydrothermal self-assembling ZnO nanorods as electron transport layer in perovskite solar cells. The efficiency of perovskite solar cells is dramatically enhanced by passivating the interface defects via atomic layer deposition of Al2O3 monolayers on ZnO nanorods. By employing Al2O3 monolayers, the power conversion efficiency (PCE) of CH3NH3PbI3 (MAPbI3) PSCs is typically boosted from ~10.38% to 14.27% on average, with the highest efficiency of 15.35%. We suggest that passivation of defects using atomic layer deposition of monolayers might provide a new pathway for improving all types of PSCs.

High quality self-ordered TiO2 nanotubes (TNTs) were grown on a conductive fluorine-doped tin oxide (FTO) coated glass by anodization of titanium thin film deposited atop. The result showed that high-density Ti films with good adhesion can be obtained by direct current (DC) magenetron sputtering at 200 ˚C. The dependence of the morphology of TiO2 nanotube on anodization time was investigated by scanning electron microscope (SEM). The TiO2 nanotubes were annealed at 500 ˚C for 180 min, which led to the transformation of the crystal structure from amorphous to anatase. The influence of the anodization time on the crystallization of nanotubes is discussed. The proposed low-cost method for fabricating TiO2 nanotubes provides an approach to enhance the efficiency of dye-sensitized solar cells (DSSCs).