Gold-silicon nanofiber synthesized by femtosecond laser radiation for enhanced light absorptance

In this study, we devised a new concept for the precise nanofabrication of Au-Si fibrous nanostructures using megahertz femtosecond laser irradiation in air and atmospheric pressure conditions. The weblike fibrous nanostructures of Au thin layer on silicon substrate, which are proposed for the application of solar cells, exhibit a specific improvement of the optical properties in visible wavelength. Varying numbers of laser interaction pulses were used to control the synthesis of the nanofibrous structures. Electron microscopy analysis revealed that the nanostructures are formed due to the aggregation of polycrystalline nanoparticles of the respective constituent materials with diameters varying between 30 and 90 nm. Measurement of the reflectance through a spectroradiometer showed that the coupling of incident electromagnetic irradiation was greatly improved over the broadband wavelength range. Lower reflectance intensity was obtained with a higher number of laser pulses due to the bulk of gold nanoparticles being agglomerated by the mechanism of fusion. This forms interweaving fibrous nanostructures which reveal a certain degree of assembly.

Gold-silicon nanofiber synthesized by femtosecond laser radiation for enhanced light absorptance

In this study, we devised a new concept for the precise nanofabrication of Au-Si fibrous nanostructures using megahertz femtosecond laser irradiation in air and atmospheric pressure conditions. The weblike fibrous nanostructures of Au thin layer on silicon substrate, which are proposed for the application of solar cells, exhibit a specific improvement of the optical properties in visible wavelength. Varying numbers of laser interaction pulses were used to control the synthesis of the nanofibrous structures. Electron microscopy analysis revealed that the nanostructures are formed due to the aggregation of polycrystalline nanoparticles of the respective constituent materials with diameters varying between 30 and 90 nm. Measurement of the reflectance through a spectroradiometer showed that the coupling of incident electromagnetic irradiation was greatly improved over the broadband wavelength range. Lower reflectance intensity was obtained with a higher number of laser pulses due to the bulk of gold nanoparticles being agglomerated by the mechanism of fusion. This forms interweaving fibrous nanostructures which reveal a certain degree of assembly.

The Effect of Red & Blue Rich LEDs vs Fluorescent Light on Lollo Rosso Lettuce Morphology and Physiology

The challenges of feeding an increasing population, an increasingly urban population and within an increasingly challenging global environment have focused ideas on new ways to grow food. Growing food in a controlled environment (CE) is not new but new technologies such as broad-spectrum LEDs and robotics are generating new opportunities. Growth recipes can be tailored to plant species in a CE and plasticity in plant responses to the environment may be utilized to make growth systems more efficient for improved yield and crop quality. Light use efficiency within CE must consider energy requirements, yield and impacts on quality. We hypothesized that understanding how plants change their morphology and physiology in response to light will allow us to identify routes to make light more efficient for delivery of high-quality produce. We focused on responses to light in Lollo rosso lettuce which produces compact, crinkly and highly pigmented leaves. We compared the spectra of the commonly used artificial light sources in indoor farming (compact fluorescence tubes, FL, and broad-spectrum light-emitting diodes, LEDs) at two irradiance levels (270 and 570 μmol m–2 s–1). We discovered LEDs (λP: 451, 634, and 665 nm) produced the same amount of produce for half the incident energy of FL (T5). At higher irradiances LEDs produced 9% thicker leaves, 13% larger rosettes and 15% greater carotenoid content. Leaves differed in light absorptance with plants grown under lower FL absorbing 30% less of mid-range wavelengths. We show that the relative efficiencies of LED and FL is a function of the irradiances compared and demonstrate the importance of understanding the asymptotes of yield and quality traits. Increasing our understanding of structural and biochemical changes that occur under different combination of wavelengths may allow us to better optimize light delivery, select for different ranges of plasticity in crop plants and further optimize light recipes.

Enhanced the light absorptance of stain-etched black Silicon decorated by TiN nanoparticles

Due to the high energy, narrow distribution and breaking through the absorption limitation, plasmon induced hot electrons has been widely applied to extend the photoresponse spectra of the semiconductor. In order to further enhance the resonance effect of local plasmon based on metallic nanostructures, we used hydrofluoric stain etching method to fabricate nanostructured black silicon (BSi) and deposited titanium nitride (TiN) nanoparticles on its surface by reactive magnetron-sputtering. The results show that the BSi modified by plasmonic TiN nanoparticles has higher absorption in wavelength range from 1100 to 2500 nm compared to that of conventional acid etching of BSi. A PIN photoelectronic detector fabricated by the proposed BSi shows excellent device performance with responsivity of 0.45A/W at 1060 nm in near infrared band.

Influence of Etching Regimes on the Reflectance of Black Silicon Films Formed by Ni-Assisted Chemical Etching

This paper examines the influence of etching regimes on the reflectance of black silicon formed by Ni-assisted chemical etching. Black silicon exhibits properties of high light absorptance. The measured minimum values of the reflectance (R-min) of black silicon with thickness of 580 nm formed by metal-assisted chemical etching (MACE) for 60 minutes at 460 lx illumination were 2,3% in the UV region (200–400 nm), 0,5% in the visible region (400–750 nm) and 0,3% in the IR region (750–1300 nm). The findings showed that the reflectance of black silicon depends on its thickness, illumination and treatment duration. In addition, the porosity and refractive index were calculated.