Single-Source Pulsed Laser Deposited Perovskite Solar Cells with > 19% Efficiency

Single-source vapor deposition of metal halide perovskites has, to date, remained challenging due to the dissimilar volatilities of the perovskite precursors, limiting the controlled transfer of multiple elements at once. This Chapter demonstrates that pulsed laser deposition (PLD) addresses the rate-control challenges of single-source evaporation, enabling solar cells with power conversion efficiencies (PCE) above 19%. For this, we combined dry mechanochemical synthesis and PLD to fabricate MA1-xFAxPbI3 and Cl-passivated MA1-xFAxPbI3 films from a single-source target. The films are grown onto hole-selective self-assembled monolayers (SAMs-2PACz), where first a thin PbI2-rich layer forms, leading to full perovskite conversion as confirmed by grazing-incidence wide-angle X-ray scattering. Onto the perovskite, an oleylammonium iodide (OAmI) post-treatment is then applied to passivate its top surface by forming a 2D perovskite film. This was followed via in-situ PL monitoring during the 2D application. Further, we found that when incorporating PbCl2 in the target and OAmI-based 2D passivation, a remarkable 19.7% PCE for p–i–n perovskite solar cells is achieved with enhanced device stability. These findings emphasize the importance of interface and passivation strategies to improve the performance of PSC-containing vapor-deposited absorbers. Further, these results represent one of the highest PCEs achieved within the state-of-the-art single-source vapor deposition methods, as far as our knowledge extends. Consequently, this study highlights the appeal of PLD to fully unlock the potential of single-source vapor-deposited perovskite towards low-cost and efficient photovoltaics

Reduced body sizes in climate-impacted tropical insect assemblages are primarily explained by range shifts

Both community composition changes due to species redistribution and within-species size shifts may alter body size structures under climate warming. Here we assess the relative contribution of these processes in community-level body size changes in tropical moth assemblages that moved uphill during a period of warming. Based on resurvey data for seven assemblages (>8000 individuals) on Mt. Kinabalu, Borneo in 1965 and 2007, we show significant wing-length reduction (mean shrinkage of 1.3% per species). Range shifts explain most size re-structuring, due to uphill shifts of relatively small species, especially at high elevations. Overall, mean forewing length shrank by ca. 5%, much of which accounted for by species range boundary shifts (3.9%), followed by within-boundary distribution changes (0.5%), and within-species size shrinkage (0.6%). We conclude that the effects of range shifting predominate, but considering species physiological responses is also important for understanding community size reorganization under climate warming

The meat of affliction: Insects and the future of food as seen in Expo 2015 (commentary)

Background: Insects are touted as a “food of the future” due to their lower environmental footprint relative to traditional livestock, raising interest in entomophagy as a sustainable diet. As such, they appeared at future-food themed Universal Exposition 2015 in Milan, Italy, in which 145 countries presented their nations’ food culture and contributions to innovative food science and technology. Scope and approach: The presence and absence of entomophagy in all the national and themed pavilions of Expo 2015 and the way developing and developed nations differed in their presentation of insects were analyzed as a microcosm of global attitudes to insects as food and the barriers towards its wider adoption. Key findings and conclusions: Only Belgium and the Netherlands presented insects in their vision for the future, and only Angola as traditional cuisine. Nations noted for active entomophagy today such as Mexico and Thailand did not mention insects at all. Efforts to serve insects faced obstacles in Italian import restrictions, which changed by the event's end. Expo 2015 illustrates challenges in promoting global entomophagy, including the need for improved rearing methods, the risks of associating insects with starvation scenarios, and the preference of Westerners for processed insects over whole

Wie Gentechnik-Gegner den Entwicklungsländern schaden

Das stetige Wachstum der Weltbevölkerung macht Innovationen in der Nahrungsmittelproduktion unabdingbar. Als Lösung wird der Einsatz von gentechnisch veränderten (GV-)Nutzpflanzen und -tieren diskutiert, vor allem für Regionen wie Afrika und Südostasien. Die Befürworter bewegen sich dabei auf einer soliden wissenschaftlichen Grundlage. GV-Lebensmittel sind sicher für den Verzehr und verfügen über ein enormes Potenzial für eine nachhaltige Lebensmittelproduktion. Doch zwei Probleme, die an entgegengesetzten Seiten der Debatte zu verorten sind, behindern die Verbreitung von GV-Technologie in den Entwicklungsländern. Zum einen die Anti-Gentechnik-Ideologie der EU, die auf eingebildeten Gesundheitsgefahren beruht; zum anderen wird die internationale Handelspolitik durch externe Interessen beeinflusst. Hinzu kommt, dass die fehlende Infrastruktur in Ländern mit Ernährungsproblemen den Einsatz der entsprechenden Technologien verhindert oder zumindest bremst. Der folgende Beitrag zeigt auf, wie unberechtigte Ängste und uneinlösbare Versprechen den Einsatz einer vielversprechenden Technologie blockieren