Surface Texturization and Interface Passivation of Mono and Polycrystalline Silicon Substrates Evaluation of the Wet Chemical Treatments by UV NIR Reflectance

The relations between light trapping behavior, structural imperfections, energetic distribution of interface state densities and interface recombination losses were investigated on as cut, saw damage etched and textured mono crystalline silicon substrates for solar cell manufacturing. Surface sensitive techniques, the field modulated surface photovoltage SPV , total hemispherical UV NIR reflectance measurements and electron microscopy SEM were employed to yield detailed information on the influence of wet chemical treatments on preparation induced texture, nano roughness and electronic properties of polished and textured silicon substrates. The correlation between UV reflectance and SPV measured surface state density has been investigated. As a result, the different contributions of micron sized texture and nanometer sized surface roughness to the reflectance signal have been separated and a measurement set up and optical model for routine evaluation of wet chemical surface texturization in production processes has been establishe

A review of stimuli-responsive polymer-based gating membranes

Uredat S, Gujare A, Runge J, Truzzolillo D, Oberdisse J, Hellweg T. A review of stimuli-responsive polymer-based gating membranes. Physical Chemistry Chemical Physics. 2024.The formation and properties of smart (stimuli-responsive) membranes are reviewed, with a special focus on temperature and pH triggering of gating to water, ions, polymers, nanoparticles, or other molecules of interest.The formation and properties of smart (stimuli-responsive) membranes are reviewed, with a special focus on temperature and pH triggering of gating to water, ions, polymers, nanoparticles, or other molecules of interest. The review is organized in two parts, starting with all-smart membranes based on intrinsically smart materials, in particular of the poly(N-isopropylacrylamide) family and similar polymers. The key steps of membrane fabrication are discussed, namely the deposition into thin films, functionalization of pores, and the secondary crosslinking of pre-existing microgel particles into membranes. The latter may be free-standing and do not necessitate the presence of a porous support layer. The temperature-dependent swelling properties of polymers provide a means of controlling the size of pores, and thus size-sensitive gating. Throughout the review, we highlight “positive” (gates open) or “negative” (closed) gating effects with respect to increasing temperature. In the second part, the functionalization of porous organic or inorganic membranes of various origins by either microgel particles or linear polymer brushes is discussed. In this case, the key steps are the adsorption or grafting mechanisms. Finally, whenever provided by the authors, the suitability of smart gating membranes for specific applications is highlighted