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The NiO/Ag/NiO (NAN) structure, a member of the oxide/metal/oxide (OMO) structures, was developed as an alternative to conventional transparent electrodes. The fabrication process employed combination of RF-magnetron sputter and e-beam evaporation techniques, and to optimize the electrode performance, the Ag layer thickness within the NAN structures was varied between 4 and 20 nm. The resulting configurations were evaluated through the Fraser-Cook and Haacke figures of merit (FoM). The optimized structure exhibited high optical transmittance of 75% and a low sheet resistance (RS) of ∼5 Ω/□. Compared to a commercial sample of indium tin oxide (ITO) coated polyethylene terephthalate (PET), the NAN/PET structures show higher Fraser-Cook FoM, closely aligned with the Haacke FoM, owing to their lower RS values. In addition, the flexural resistance of the electrodes was assessed by subjecting the samples to 10,000 bending cycles. Following this test, the RS value of ITO/PET increased 26.3 times to 3312.89 Ω/□, while the NAN/PET only increased 1.25 times to 7.82 Ω/□. Even the least performing NAN sample, deposited on polyethylene naphthalate (NAN/PEN), experienced a moderate increase in resistance, stabilizing at 59.93 Ω/□. The obtained results highlight the great potential of the NAN structure as an electrode for flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

Throughout the last decade, the expansion of food testing has been gradually moving towards ordinary high throughput screening methods performed on-site. The demand for point-of-care testing, able to distinguish molecular signatures with high accuracy, sensitivity and specificity has been significantly increasing. This new requirement relies on the on-site detection and monitorization of molecular signatures suitable for the surveillance of food production and processing. The widespread use of antibiotics has contributed to disease control of livestock but has also created problems for the dairy industry and consumers. Its therapeutic and subtherapeutic use has increased the risk of contamination in milk in enough concentrations to cause economic losses to the dairy industry and have a health impact in highly sensitive individuals. This study focuses on the development of a simple Surface-Enhanced Raman Spectroscopy (SERS) method for fast high throughput screening of tetracycline (TET) in milk. For this, we integrate a paper-based low-cost, fully recyclable and highly stable SERS platform, with a minimal sample preparation protocol. A two-microliter sample of milk solutions spiked with TET (from 0.01 to 1000 ppm) is dried on a silver nanoparticle coated cardboard substrate and measured via a Raman spectrophotometer. The SERS substrate showed to be extremely stable with a shelf life of several months. A global spectrum principal component analysis approach was used to test all the detected vibrational modes and their correlation with TET concentration. Peak intensity ratios (455 cm−1/1280 cm−1 and 874 cm−1/1397 cm−1) were found to be correlated with TET concentrations in milk, achieving a sensitivity as low as 0.1 ppm. Results indicate that this SERS method combined with portable Raman spectrometer is a potential tool that can be used on-site for the monitoring of TET residues and other antibiotics. [ABSTRACT FROM AUTHOR]

Advanced light management techniques can enhance the sunlight absorption of perovskite solar cells (PSCs). When located at the front, they may act as a UV barrier, which is paramount for protecting the perovskite layer against UV-enabled degradation. Although it was recently shown that photonic structures such as Escher-like patterns could approach the theoretical Lambertian-limit of light trapping, it remains challenging to also implement UV protection properties for these diffractive structures while maintaining broadband absorption gains. Here, we propose a checkerboard (CB) tile pattern with designated UV photon conversion capability. Through a combined optical and electrical modeling approach, this photonic structure can increase photocurrent and power conversion efficiency in ultrathin PSCs by 25.9% and 28.2%, respectively. We further introduce a luminescent down-shifting encapsulant that converts the UV irradiation into Visible photons matching the solar cell absorption spectrum. To this end, experimentally obtained absorption and emission profiles of state-of-the-art down-shifting materials (i.e., lanthanide-based organic-inorganic hybrids) are used to predict potential gains from harnessing the UV energy. We demonstrate that at least 94% of the impinging UV radiation can be effectively converted into the Visible spectral range. Photonic protection from high-energy photons contributes to the market deployment of perovskite solar cell technology, and may become crucial for Space applications under AM0 illumination. By combining light trapping with luminescent downshifting layers, this work unravels a potential photonic solution to overcome UV degradation in PSCs while circumventing optical losses in ultrathin cells, thus improving both performance and stability., (© 2024. The Author(s).)