Polyurethanes (PUs), formed by the reaction of diisocyanates with polyols (or equivalent) in the presence of a catalyst, have a wide variety of industrial uses. Much recent attention has focused on their biomedical applications, owing to their biocompatibility, biodegradability and tailorable chemical and physical forms. Examples of such application areas include antibacterial surfaces and catheters, drug delivery vehicles, stents, surgical dressings/pressure sensitive adhesives, tissue engineering scaffolds and electrospinning, nerve generation, cardiac patches and PU coatings for breast implants. Following a brief introduction to PUs, this review surveys selected articles, mostly from 2014 to 2017, that highlight this diverse range of biomedical applications offered by PU materials and coatings.
We report fabrication of nanostructured, laser-doped selective emitter (LDSE) silicon solar cells with power conversion efficiency of 18.1 % and a fill factor (FF) of 80.1 %. The nanostructured solar cells were realized through a single step, mask-less, scalable reactive ion etch (RIE) texturing of the surface. The selective emitter was formed by means of laser doping using a continuous wave (CW) laser and subsequent contact formation using light-induced plating of Ni and Cu. The combination of RIE-texturing and a LDSE cell design has to our knowledge not been demonstrated previously. The resulting efficiency indicates a promising potential, especially considering that the cell reported in this work is the first proof-of-concept and that the fabricated cell is not fully optimized in terms of plating, emitter sheet resistance and surface passivation. Due to the scalable nature and simplicity of RIE-texturing as well as the LDSE process, we consider this specific combination a promising candidate for a cost-efficient process for future Si solar cells.
In this letter, we report on significant changes caused after dark annealing to the kinetics of the carrier‐induced defect, present in p‐type multi‐crystalline silicon PERC cells. The characteristic shapes of the degradation and regeneration curves under light soaking at 75 °C are dramatically altered, depending on the temperature of an initial dark anneal on the non‐degraded cell. Dark annealing for a fixed time (2.5 h) at temperatures of 200 °C or below, is found to accelerate both the subsequent degradation and regeneration rate and the degradation severity, while at higher temperatures it appears that a possible second defect with a significantly longer degradation and regeneration rate is activated. Through a further increase of the dark annealing temperature, the magnitude of this slow degradation is suppressed. This data provides essential information into the role that thermal history plays in the behavior of the still unidentified defect or defects, which is crucial for future studies of the degradation and methods to mitigate it.
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