Water Availability Is the Main Climate Driver of Neotropical Tree Growth

• Climate models for the coming century predict rainfall reduction in the Amazonian region, including change in water availability for tropical rainforests. Here, we test the extent to which climate variables related to water regime, temperature and irradiance shape the growth trajectories of neotropical trees. • We developed a diameter growth model explicitly designed to work with asynchronous climate and growth data. Growth trajectories of 205 individual trees from 54 neotropical species censused every 2 months over a 4-year period were used to rank 9 climate variables and find the best predictive model. • About 9% of the individual variation in tree growth was imputable to the seasonal variation of climate. Relative extractable water was the main predictor and alone explained more than 60% of the climate effect on tree growth, i.e. 5.4% of the individual variation in tree growth. Furthermore, the global annual tree growth was more dependent on the diameter increment at the onset of the rain season than on the duration of dry season. • The best predictive model included 3 climate variables: relative extractable water, minimum temperature and irradiance. The root mean squared error of prediction (0.035 mm.d–1) was slightly above the mean value of the growth (0.026 mm.d–1). • Amongst climate variables, we highlight the predominant role of water availability in determining seasonal variation in tree growth of neotropical forest trees and the need to include these relationships in forest simulators to test, in silico, the impact of different climate scenarios on the future dynamics of the rainforest

Synthesis and characterization of alkylene-bridged silsesquicarbodiimide hybrid xerogels

Hybrid polymers consisting of flexible organic chains within an inorganic silsesquicarbodiimide network of the type [(NCN)1.5Si-(CH2)x-Si(NCN)1.5]n (where x=2, 6, and 8) were prepared by mild sol–gel polycondensation reactions of bis(trichlorosilyl)alkanes and bis(trimethylsilyl)carbodiimide. The presence of the NCN groups in xerogel structures was identified by FTIR spectra. The composition and molecular structures were characterized by elemental analysis, solid-state 13C CP MAS- and 29Si CP MAS-NMR spectroscopies, and XRD. Scanning as well as transmission electron microscopies were used to examine the morphology of the xerogels. In addition, the pore structure of the materials was examined by the gas adsorption (BET) method and it is found that the surface area decreased with increasing length of the alkylene spacing group. Hybrid polymers consisting of flexible organic chains within an inorganic silsesquicarbodiimide network of the type [(NCN)1.5Si-(CH2)x-Si(NCN)1.5]n (where x=2, 6, and 8) were prepared by mild sol–gel polycondensation reactions of bis(trichlorosilyl)alkanes and bis(trimethylsilyl)carbodiimide. The presence of the NCN groups in xerogel structures was identified by FTIR spectra

The role of lead precursors in driving competitive crystallization reactions during the formation of 2D perovskites

Two-dimensional (2D) lead halide perovskites are an exciting class of materials currently being extensively explored for both photovoltaics and optoelectronic applications. The ionic nature of these materials makes them ideal candidates for solution processing into both thin films and nanostructured crystals. However, a complete mechanistic description of 2D perovskite crystallization in solution is still missing due to the intricacy of process parameters and intermediates. Here, we investigate the role of different solid lead precursors (PbO2, PbI2, PbCO3) on the crystallization of pure-phase, n=1, Ruddleson-Popper 2D perovskite BA2PbI4, during a two-step drop-cast-based synthesis. While BA2PbI4 is formed in all cases, the nucleation and resulting morphology are strongly dependent on the choice of precursor, where the three lead precursors differ from each other in terms of their Pb-ion oxidation state, crystal structure, and material class. We use in-situ optical live imaging during synthesis to reveal clear differences in crystallization kinetics of the same 2D perovskite as a function of the lead precursor. We discern three competing mechanisms in the Pb-precursor for the formation of BA2PbI4: dissolution/complexation, BAI intercalation, and solid-state conversion. The differences in the oxidation state and solubility of the starting lead precursor in halide-rich solution play a key role in defining the crystallization pathway(s). This work demonstrates the importance of lead precursors in defining the nucleation and growth of perovskites thereby advancing the existing solution-processing techniques. Understanding how 2D perovskite crystals form in solution is key towards full control over their growth and optoelectronic properties, which will enable new types of physical phenomena and devices

The role of Pb oxidation state of the precursor in the formation of 2D perovskite microplates.

Acknowledgements: This work is part of the Dutch Research Council (NWO) and was performed at the NWO-Institute AMOLF. The authors would like to thank Daniël Koletzki for his contributions in enabling the in situ optical setup. L. S. D. A and E. A. L. acknowledge the D3N project (project no. 17972 of the research programme HTSM2019 from the NWO-TTW Domain), which is (partly) financed by the Dutch Research Council (NWO). S. v. D. acknowledges OCENW.KLEIN.155, which is financed by the Dutch Research Council (NWO). The work of G. G. and J. B. was supported by the EPSRC International Centre to Centre under grant no. EP/S030638/1. A. v. D. W. and W. L. N. acknowledges the Vernieuwingsimpuls Vidi research program “Shaping up materials” with project no. 016.Vidi.189.083, which is partly financed by the Dutch Research Council (NWO). B. E. and I. S. acknowledge OCENW.KLEIN.076, which is financed by the Dutch Research Council (NWO).Two-dimensional (2D) lead halide perovskites are an exciting class of materials currently being extensively explored for photovoltaics and other optoelectronic applications. Their ionic nature makes them ideal candidates for solution processing into both thin films and nanostructured crystals. Understanding how 2D lead halide perovskite crystals form is key towards full control over their physical properties, which may enable new physical phenomena and devices. Here, we investigate the effects of the Pb oxidation state of the initial inorganic precursor on the growth of pure-phase (n = 1) - Popper 2D perovskite BA2PbI4 in single-step synthesis. We examine the different crystallisation routes in exposing PbO2 and PbI2 powders to a BAI : IPA organo-halide solution, by combining in situ optical microscopy, UV-VIS spectroscopy and time-resolved high performance liquid chromatography. So far, works using PbO2 to synthesise 3D LHPs introduce a preceding step to reduce PbO2 into either PbO or PbI2. In this work, we find that BA2PbI4 is directly formed when exposing PbO2 to BAI : IPA without the need for an external reducing agent. We explain this phenomenon by the spontaneous reduction/oxidation of PbO2/BAI that occurs under iodine-rich conditions. We observe differences in the final morphology (rectangles vs. octagons) and nanocrystal growth rate, which we explain through the different chemistry and iodoplumbate complexes involved in each case. As such, this work spans the horizon of usable lead precursors and offers a new turning knob to control crystal growth in single-step LHP synthesis

Vapor phase deposition of perovskite photovoltaics: short track to commercialization? †

Acknowledgements: The work performed at the National Renewable Energy Laboratory (NREL) was supported by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) Agreement Number DE-EE0009017 and NREL, operated by the Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under contract number DE-AC36-08GO28308. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. The authors furthermore acknowledge the support by the Federal Ministry for Economic Affairs and Climate Action of Germany under grant agreement 03EE1123A (project SHAPE) as well as the European Union through HORIZON EUROPE Research and Innovation Actions under grant agreement number 101075330 (project NEXUS). Views and opinions expressed are those of the authors only and do not necessarily reflect those of the European Union or the European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible. Financial support for the creation of the cover artwork by the Ministry of Trade, Industry, and Energy of the Republic of Korea under the grant agreement 202300302107 was highly appreciated. The authors further recognize the kind worldwide support by the many companies in the field of perovskite-based photovoltaics that contributed to the industry survey and gave us first-hand insights into the commercialization of this technology.While perovskite-based photovoltaics (PV) is progressing toward commercialization, it remains an open question which fabrication technology – solution-based, vapor-based, or combinations – will pave the way to faster economic breakthrough. The vast majority of research studies make use of solution-processed perovskite thin films, which benefit from a rapid optimization feedback and inexpensive to procure tools in modern research laboratories, but vapor phase deposition processes dominate today's established thin-film manufacturing. As research and development of vapor phase processed perovskite thin films are still strongly underrepresented in literature, their full potential is yet to be identified. In this collaborative perspective of academic influenced by industrial views, we convey a balanced viewpoint on the prospects of vapor-based processing of perovskite PV at an industrial scale. Our perspective highlights the conceptual advantages of vapor phase deposition, discusses the most crucial process parameters in a technology assessment, contains an overview about relevant global industry clusters, and provides an outlook on the commercialization perspectives of the perovskite technology in general