The development of an electrically-conductive anticorrosion coating with self-healing capability for metallic surface protection constitutes a priority concern for many key industrial applications. While current technologies largely rely on hazardous chromate-based corrosion inhibitors, this work proposes a simple polymer-based layer-by-layer (LBL) architecture, implemented using easy and fast fabrication techniques. Moreover, this smart coating architecture relies on three environmentally friendly polymers namely polyethylenimine (PEI), polystyrenesulfonate (PSS) and 8-hydroxyquinoline (8HQ) respectively serving as poly-cation, poly-anion and as corrosion inhibitor. Here, this protective coating is deposited and tested on the widely-used Aluminium 2024 alloy to achieve long term protection against corrosion. When structural damages to the coating occur, the inhibitor agents are released to passivate the surface. Raman micro-spectroscopy measurements confirm this effective self-healing capability. This chromate-free coating shows great promises for multiple aerospace, construction and automotive applications.

In this study, a feasible approach for UV–vis photodetection using hybrid heterojunction by integrating porous silicon and TiO ₂ thin film is demonstrated. The photodetector demonstrates excellent photoresponse by three orders of magnitude enhancement and fast rise/decay time constants of 0.16/0.14 ms. Under small bias (1 V), the photodetector exhibits very high responsivity up to 40 A W ⁻¹ at 532 nm irradiation over a broadband wavelength range from 300–700 nm. The heterostructure geometry yields high-performance devices useful for many optoelectronic and biomedical applications.

We report significantly improved silicon nanowire/TiO₂ n⁺–n heterojunction solar cells prepared by sol–gel synthesis of TiO₂ thin film atop vertically aligned silicon nanowire arrays obtained by facile metal-assisted wet electroless chemical etching of a bulk highly doped n-type silicon wafer. As we show here, chemical treatment of the nanowire arrays prior to depositing the sol–gel precursor has dramatic consequences on the device performance. While hydrofluoric treatment to remove the native oxide already improves significantly the device performances, hydrobromic (HBr) treatment consistently yields by far the best device performances with power conversion efficiencies ranging between 4.2 and 6.2% with fill factors up to 60% under AM 1.5G illumination. In addition to yield high-quality and easy to produce solar cell devices, these findings regarding the surface treatment of silicon nanowires with HBr suggest that HBr could contribute to the enhancement of the device performance not only for solar cells but also for other optoelectronics devices based on semiconductor nanostructures.

Due to its high refractive index, reflectance is often a problem when using Germanium for optoelectronic devices integration. In this work, we propose an effective and low-cost nano-texturing method for considerably reducing the reflectance of bulk Germanium. To do so, uniform V-shape pit arrays are produced by wet electroless chemical etching in a 3:1 volume ratio of highly-concentrated hydrochloridric and nitric acids or so-called aqua regia bath using immersion times ranging from 5 to 60 min. The resulting pit morphology, the crystalline structure of the surface and the changes in surface chemistry after nano-patterning are all investigated. Finally, broadband near-infrared reflectance measurements confirm a significant reduction using this simple wet etching protocol, while maintaining a crystalline, dioxide-free, and hydrogen-passivated surface. It is important to mention that reflectance could be further reduced using deeper pits. However, most optoelectronic applications such as photodetectors and solar cells require relatively shallow patterning of the Germanium to allow formation of a pn-junction close to the surface.